Add support for cover art via the Cover Art Archive (#17)

package.json

@@ -36,6 +36,7 @@
     "test:coverage": "cross-env NODE_ENV=test nyc npm run test:only",
     "test:only": "cross-env VCR_MODE=playback ava",
     "test:record": "cross-env VCR_MODE=record ava",
+    "test:record-new": "cross-env VCR_MODE=cache ava --serial",
     "test:watch": "npm run test:only -- --watch",
     "update-schema": "npm run -s print-schema:json > schema.json"
   },

src/api/client.js

@@ -1,11 +1,10 @@
 import request from 'request'
 import retry from 'retry'
-import qs from 'qs'
 import ExtendableError from 'es6-error'
-import RateLimit from './rate-limit'
+import RateLimit from '../rate-limit'
-import pkg from '../package.json'
+import pkg from '../../package.json'
 
-const debug = require('debug')('graphbrainz:api')
+const debug = require('debug')('graphbrainz:api/client')
 
 // If the `request` callback returns an error, it indicates a failure at a lower
 // level than the HTTP response itself. If it's any of the following error
@@ -21,19 +20,20 @@ const RETRY_CODES = {
   EAI_AGAIN: true
 }
 
-export class MusicBrainzError extends ExtendableError {
+export class ClientError extends ExtendableError {
   constructor (message, statusCode) {
     super(message)
     this.statusCode = statusCode
   }
 }
 
-export default class MusicBrainz {
+export default class Client {
   constructor ({
     baseURL = process.env.MUSICBRAINZ_BASE_URL || 'http://musicbrainz.org/ws/2/',
     userAgent = `${pkg.name}/${pkg.version} ` +
       `( ${pkg.homepage || pkg.author.url || pkg.author.email} )`,
     extraHeaders = {},
+    errorClass = ClientError,
     timeout = 60000,
     // MusicBrainz API requests are limited to an *average* of 1 req/sec.
     // That means if, for example, we only need to make a few API requests to
@@ -41,8 +41,8 @@ export default class MusicBrainz {
     // we then wait a few seconds before making more. In practice this can
     // seemingly be set to about 5 requests every 5 seconds before we're
     // considered to exceed the rate limit.
-    limit = 5,
+    limit = 1,
-    period = 5500,
+    period = 1000,
     concurrency = 10,
     retries = 10,
     // It's OK for `retryDelayMin` to be less than one second, even 0, because
@@ -57,6 +57,7 @@ export default class MusicBrainz {
     this.baseURL = baseURL
     this.userAgent = userAgent
     this.extraHeaders = extraHeaders
+    this.errorClass = errorClass
     this.timeout = timeout
     this.limiter = new RateLimit({ limit, period, concurrency })
     this.retryOptions = {
@@ -73,36 +74,48 @@ export default class MusicBrainz {
    * `RETRY_CODES`.
    */
   shouldRetry (err) {
-    if (err instanceof MusicBrainzError) {
+    if (err instanceof this.errorClass) {
       return err.statusCode >= 500 && err.statusCode < 600
     }
     return RETRY_CODES[err.code] || false
   }
 
+  parseErrorMessage (response, body) {
+    return typeof body === 'string' && body ? body : `${response.statusCode}`
+  }
+
   /**
    * Send a request without any retrying or rate limiting.
    * Use `get` instead.
    */
-  _get (path, params, info = {}) {
+  _get (path, options = {}, info = {}) {
     return new Promise((resolve, reject) => {
-      const options = {
+      options = {
         baseUrl: this.baseURL,
         url: path,
-        qs: { ...params, fmt: 'json' },
-        json: true,
         gzip: true,
-        headers: { 'User-Agent': this.userAgent, ...this.extraHeaders },
+        timeout: this.timeout,
-        timeout: this.timeout
+        ...options,
+        headers: {
+          'User-Agent': this.userAgent,
+          ...this.extraHeaders,
+          ...options.headers
+        }
       }
 
-      debug(`Sending request. url=${path} attempt=${info.currentAttempt}`)
+      debug(`Sending request. url=${this.baseURL}${path} attempt=${info.currentAttempt}`)
 
       request(options, (err, response, body) => {
         if (err) {
+          debug(`Error: “${err}” url=${this.baseURL}${path}`)
           reject(err)
-        } else if (response.statusCode !== 200) {
+        } else if (response.statusCode >= 400) {
-          const message = (body && body.error) || ''
+          const message = this.parseErrorMessage(response, body)
-          reject(new MusicBrainzError(message, response.statusCode))
+          debug(`Error: “${message}” url=${this.baseURL}${path}`)
+          const ClientError = this.errorClass
+          reject(new ClientError(message, response.statusCode))
+        } else if (options.method === 'HEAD') {
+          resolve(response.headers)
         } else {
           resolve(body)
         }
@@ -113,7 +126,7 @@ export default class MusicBrainz {
   /**
    * Send a request with retrying and rate limiting.
    */
-  get (path, params) {
+  get (path, options = {}) {
     return new Promise((resolve, reject) => {
       const fn = this._get.bind(this)
       const operation = retry.operation(this.retryOptions)
@@ -121,7 +134,7 @@ export default class MusicBrainz {
         // This will increase the priority in our `RateLimit` queue for each
         // retry, so that newer requests don't delay this one further.
         const priority = currentAttempt
-        this.limiter.enqueue(fn, [path, params, { currentAttempt }], priority)
+        this.limiter.enqueue(fn, [path, options, { currentAttempt }], priority)
           .then(resolve)
           .catch(err => {
             if (!this.shouldRetry(err) || !operation.retry(err)) {
@@ -131,64 +144,4 @@ export default class MusicBrainz {
       })
     })
   }
-
-  stringifyParams (params) {
-    if (Array.isArray(params.inc)) {
-      params = {
-        ...params,
-        inc: params.inc.join('+')
-      }
-    }
-    if (Array.isArray(params.type)) {
-      params = {
-        ...params,
-        type: params.type.join('|')
-      }
-    }
-    if (Array.isArray(params.status)) {
-      params = {
-        ...params,
-        status: params.status.join('|')
-      }
-    }
-    return qs.stringify(params, {
-      skipNulls: true,
-      filter: (key, value) => value === '' ? undefined : value
-    })
-  }
-
-  getURL (path, params) {
-    const query = params ? this.stringifyParams(params) : ''
-    return query ? `${path}?${query}` : path
-  }
-
-  getLookupURL (entity, id, params) {
-    if (id == null) {
-      return this.getBrowseURL(entity, params)
-    }
-    return this.getURL(`${entity}/${id}`, params)
-  }
-
-  lookup (entity, id, params = {}) {
-    const url = this.getLookupURL(entity, id, params)
-    return this.get(url)
-  }
-
-  getBrowseURL (entity, params) {
-    return this.getURL(entity, params)
-  }
-
-  browse (entity, params = {}) {
-    const url = this.getBrowseURL(entity, params)
-    return this.get(url)
-  }
-
-  getSearchURL (entity, query, params) {
-    return this.getURL(entity, { ...params, query })
-  }
-
-  search (entity, query, params = {}) {
-    const url = this.getSearchURL(entity, query, params)
-    return this.get(url)
-  }
 }

src/api/cover-art-archive.js

@@ -0,0 +1,47 @@
+import Client, { ClientError } from './client'
+
+export class CoverArtArchiveError extends ClientError {}
+
+export default class CoverArtArchive extends Client {
+  constructor ({
+    baseURL = process.env.COVER_ART_ARCHIVE_BASE_URL || 'http://coverartarchive.org/',
+    errorClass = CoverArtArchiveError,
+    limit = 10,
+    period = 1000,
+    ...options
+  } = {}) {
+    super({ baseURL, errorClass, limit, period, ...options })
+  }
+
+  parseErrorMessage (response, body) {
+    if (typeof body === 'string' && body.startsWith('<!')) {
+      const heading = /<h1>([^<]+)<\/h1>/i.exec(body)
+      const message = /<p>([^<]+)<\/p>/i.exec(body)
+      return `${heading ? heading[1] + ': ' : ''}${message ? message[1] : ''}`
+    }
+    return super.parseErrorMessage(response, body)
+  }
+
+  getImagesURL (entity, mbid) {
+    return `${entity}/${mbid}`
+  }
+
+  images (entity, mbid) {
+    const url = this.getImagesURL(entity, mbid)
+    return this.get(url, { json: true })
+  }
+
+  getImageURL (entity, mbid, typeOrID = 'front', size) {
+    let url = `${entity}/${mbid}/${typeOrID}`
+    if (size != null) {
+      url += `-${size}`
+    }
+    return url
+  }
+
+  imageURL (entity, mbid, typeOrID = 'front', size) {
+    const url = this.getImageURL(entity, mbid, typeOrID, size)
+    return this.get(url, { method: 'HEAD', followRedirect: false })
+      .then(headers => headers.location)
+  }
+}

src/api/index.js

@@ -0,0 +1,10 @@
+import MusicBrainz, { MusicBrainzError } from './musicbrainz'
+import CoverArtArchive, { CoverArtArchiveError } from './cover-art-archive'
+
+export {
+  MusicBrainz as default,
+  MusicBrainz,
+  MusicBrainzError,
+  CoverArtArchive,
+  CoverArtArchiveError
+}

src/api/musicbrainz.js

@@ -0,0 +1,83 @@
+import qs from 'qs'
+import Client, { ClientError } from './client'
+
+export class MusicBrainzError extends ClientError {}
+
+export default class MusicBrainz extends Client {
+  constructor ({
+    baseURL = process.env.MUSICBRAINZ_BASE_URL || 'http://musicbrainz.org/ws/2/',
+    errorClass = MusicBrainzError,
+    limit = 5,
+    period = 5500,
+    ...options
+  } = {}) {
+    super({ baseURL, errorClass, limit, period, ...options })
+  }
+
+  parseErrorMessage (response, body) {
+    if (body && body.error) {
+      return body.error
+    }
+    return super.parseErrorMessage(response, body)
+  }
+
+  stringifyParams (params) {
+    if (Array.isArray(params.inc)) {
+      params = {
+        ...params,
+        inc: params.inc.join('+')
+      }
+    }
+    if (Array.isArray(params.type)) {
+      params = {
+        ...params,
+        type: params.type.join('|')
+      }
+    }
+    if (Array.isArray(params.status)) {
+      params = {
+        ...params,
+        status: params.status.join('|')
+      }
+    }
+    return qs.stringify(params, {
+      skipNulls: true,
+      filter: (key, value) => value === '' ? undefined : value
+    })
+  }
+
+  getURL (path, params) {
+    const query = params ? this.stringifyParams(params) : ''
+    return query ? `${path}?${query}` : path
+  }
+
+  getLookupURL (entity, id, params) {
+    if (id == null) {
+      return this.getBrowseURL(entity, params)
+    }
+    return this.getURL(`${entity}/${id}`, params)
+  }
+
+  lookup (entity, id, params = {}) {
+    const url = this.getLookupURL(entity, id, params)
+    return this.get(url, { json: true, qs: { fmt: 'json' } })
+  }
+
+  getBrowseURL (entity, params) {
+    return this.getURL(entity, params)
+  }
+
+  browse (entity, params = {}) {
+    const url = this.getBrowseURL(entity, params)
+    return this.get(url, { json: true, qs: { fmt: 'json' } })
+  }
+
+  getSearchURL (entity, query, params) {
+    return this.getURL(entity, { ...params, query })
+  }
+
+  search (entity, query, params = {}) {
+    const url = this.getSearchURL(entity, query, params)
+    return this.get(url, { json: true, qs: { fmt: 'json' } })
+  }
+}

src/index.js

@@ -1,7 +1,7 @@
 import express from 'express'
 import graphqlHTTP from 'express-graphql'
 import compression from 'compression'
-import MusicBrainz from './api'
+import MusicBrainz, { CoverArtArchive } from './api'
 import schema from './schema'
 import createLoaders from './loaders'
 
@@ -11,13 +11,17 @@ const formatError = (err) => ({
   stack: err.stack
 })
 
-const middleware = ({ client = new MusicBrainz(), ...options } = {}) => {
+const middleware = ({
+  client = new MusicBrainz(),
+  coverArtClient = new CoverArtArchive(),
+  ...options
+} = {}) => {
   const DEV = process.env.NODE_ENV !== 'production'
   const graphiql = DEV || process.env.GRAPHBRAINZ_GRAPHIQL === 'true'
-  const loaders = createLoaders(client)
+  const loaders = createLoaders(client, coverArtClient)
   return graphqlHTTP({
     schema,
-    context: { client, loaders },
+    context: { client, coverArtClient, loaders },
     pretty: DEV,
     graphiql,
     formatError: DEV ? formatError : undefined,

src/loaders.js

@@ -5,7 +5,7 @@ import { toPlural } from './types/helpers'
 const debug = require('debug')('graphbrainz:loaders')
 const ONE_DAY = 24 * 60 * 60 * 1000
 
-export default function createLoaders (client) {
+export default function createLoaders (client, coverArtClient) {
   // All loaders share a single LRU cache that will remember 8192 responses,
   // each cached for 1 day.
   const cache = LRUCache({
@@ -27,23 +27,6 @@ export default function createLoaders (client) {
           // Store the entity type so we can determine what type of object this
           // is elsewhere in the code.
           entity._type = entityType
-          entity._inc = params.inc
-          if (entityType === 'discid' && entity.releases) {
-            entity.releases.forEach(release => {
-              release._type = 'release'
-              release._inc = params.inc
-            })
-          } else if (entityType === 'isrc' && entity.recordings) {
-            entity.recordings.forEach(recording => {
-              recording._type = 'recording'
-              recording._inc = params.inc
-            })
-          } else if (entityType === 'iswc' && entity.works) {
-            entity.works.forEach(work => {
-              work._type = 'work'
-              work._inc = params.inc
-            })
-          }
         }
         return entity
       })
@@ -61,7 +44,6 @@ export default function createLoaders (client) {
           // Store the entity type so we can determine what type of object this
           // is elsewhere in the code.
           entity._type = entityType
-          entity._inc = params.inc
         })
         return list
       })
@@ -79,15 +61,45 @@ export default function createLoaders (client) {
           // Store the entity type so we can determine what type of object this
           // is elsewhere in the code.
           entity._type = entityType
-          entity._inc = params.inc
         })
         return list
       })
     }))
   }, {
-    cacheKeyFn: (key) => client.getSearchURL(...key),
+    cacheKeyFn: key => client.getSearchURL(...key),
     cacheMap: cache
   })
 
-  return { lookup, browse, search }
+  const coverArt = new DataLoader(keys => {
+    return Promise.all(keys.map(key => {
+      const [ entityType, id ] = key
+      return coverArtClient.images(...key).catch(err => {
+        if (err.statusCode === 404) {
+          return { images: [] }
+        }
+        throw err
+      }).then(coverArt => {
+        coverArt._parentType = entityType
+        coverArt._parentID = id
+        if (entityType === 'release') {
+          coverArt._release = id
+        } else {
+          coverArt._release = coverArt.release && coverArt.release.split('/').pop()
+        }
+        return coverArt
+      })
+    }))
+  }, {
+    cacheKeyFn: key => `cover-art/${coverArtClient.getImagesURL(...key)}`,
+    cacheMap: cache
+  })
+
+  const coverArtURL = new DataLoader(keys => {
+    return Promise.all(keys.map(key => coverArtClient.imageURL(...key)))
+  }, {
+    cacheKeyFn: key => `cover-art/url/${coverArtClient.getImageURL(...key)}`,
+    cacheMap: cache
+  })
+
+  return { lookup, browse, search, coverArt, coverArtURL }
 }

src/types/cover-art-image.js

@@ -0,0 +1,72 @@
+import {
+  GraphQLObjectType,
+  GraphQLNonNull,
+  GraphQLList,
+  GraphQLBoolean,
+  GraphQLString,
+  GraphQLInt
+} from 'graphql/type'
+import { URLString } from './scalars'
+
+export const CoverArtImageThumbnails = new GraphQLObjectType({
+  name: 'CoverArtImageThumbnails',
+  description: `URLs for thumbnails of different sizes for a particular piece of
+cover art.`,
+  fields: () => ({
+    small: {
+      type: URLString,
+      description: `The URL of a small version of the cover art, where the
+maximum dimension is 250px.`
+    },
+    large: {
+      type: URLString,
+      description: `The URL of a large version of the cover art, where the
+maximum dimension is 500px.`
+    }
+  })
+})
+
+export default new GraphQLObjectType({
+  name: 'CoverArtImage',
+  description: 'An individual piece of album artwork from the [Cover Art Archive](https://musicbrainz.org/doc/Cover_Art_Archive).',
+  fields: () => ({
+    fileID: {
+      type: new GraphQLNonNull(GraphQLString),
+      description: 'The Internet Archive’s internal file ID for the image.',
+      resolve: image => image.id
+    },
+    image: {
+      type: new GraphQLNonNull(URLString),
+      description: 'The URL at which the image can be found.'
+    },
+    thumbnails: {
+      type: CoverArtImageThumbnails,
+      description: 'A set of thumbnails for the image.'
+    },
+    front: {
+      type: new GraphQLNonNull(GraphQLBoolean),
+      description: 'Whether this image depicts the “main front” of the release.'
+    },
+    back: {
+      type: new GraphQLNonNull(GraphQLBoolean),
+      description: 'Whether this image depicts the “main back” of the release.'
+    },
+    types: {
+      type: new GraphQLList(GraphQLString),
+      description: `A list of [image types](https://musicbrainz.org/doc/Cover_Art/Types)
+describing what part(s) of the release the image includes.`
+    },
+    edit: {
+      type: GraphQLInt,
+      description: 'The MusicBrainz edit ID.'
+    },
+    approved: {
+      type: GraphQLBoolean,
+      description: 'Whether the image was approved by the MusicBrainz edit system.'
+    },
+    comment: {
+      type: GraphQLString,
+      description: 'A free-text comment left for the image.'
+    }
+  })
+})

src/types/cover-art.js

@@ -0,0 +1,188 @@
+import {
+  GraphQLObjectType,
+  GraphQLList,
+  GraphQLNonNull,
+  GraphQLBoolean,
+  GraphQLInt
+} from 'graphql/type'
+import CoverArtImage from './cover-art-image'
+import { CoverArtImageSize } from './enums'
+import Release from './release'
+import { URLString } from './scalars'
+import { resolveLookup } from '../resolvers'
+import { getFields } from '../util'
+
+/**
+ * Return a resolver that will call `resolveFn` only if the requested field on
+ * the object is null or not present.
+ */
+function createFallbackResolver (resolveFn) {
+  return function resolve (coverArt, args, context, info) {
+    const value = coverArt[info.fieldName]
+    if (value == null) {
+      return resolveFn(coverArt, args, context, info)
+    }
+    return value
+  }
+}
+
+function resolveImage (coverArt, { size }, { loaders }, info) {
+  if (size === 'FULL') {
+    size = null
+  }
+  const field = info.fieldName
+  if (coverArt.images) {
+    const matches = coverArt.images.filter(image => image[field])
+    if (!matches.length) {
+      return null
+    } else if (matches.length === 1) {
+      const match = matches[0]
+      if (size === 250) {
+        return match.thumbnails.small
+      } else if (size === 500) {
+        return match.thumbnails.large
+      } else {
+        return match.image
+      }
+    }
+  }
+  if (coverArt[field] !== false) {
+    const {
+      _parentType: entityType = 'release',
+      _parentID: id = coverArt._release
+    } = coverArt
+    return loaders.coverArtURL.load([entityType, id, field, size])
+  }
+}
+
+const size = {
+  type: CoverArtImageSize,
+  description: `The size of the image to retrieve. By default, the returned
+image will have its full original dimensions, but certain thumbnail sizes may be
+retrieved as well.`,
+  defaultValue: null
+}
+
+/**
+ * Get around both the circular dependency between the release and cover art
+ * types, and not have to define an identical `release` field twice on
+ * `ReleaseCoverArt` and `ReleaseGroupCoverArt`.
+ */
+function createReleaseField () {
+  return {
+    type: new GraphQLNonNull(Release),
+    description: 'The particular release shown in the returned cover art.',
+    resolve: (coverArt, args, context, info) => {
+      const id = coverArt._release
+      const fields = Object.keys(getFields(info))
+      if (fields.length > 1 || fields[0] !== 'mbid') {
+        return resolveLookup(coverArt, { mbid: id }, context, info)
+      }
+      return { id }
+    }
+  }
+}
+
+// This type combines two sets of data from different places. One is a *summary*
+// of the images available at the Cover Art Archive, found in the `cover-art-archive`
+// field on releases. The other is the actual list of images with their metadata,
+// fetched from the Cover Art Archive itself rather than MusicBrainz. Depending
+// on what fields are requested, we may only need to fetch one or the other, or
+// both. Much of the summary data can be reconstructed if we already fetched the
+// full image list, for example.
+export const ReleaseCoverArt = new GraphQLObjectType({
+  name: 'ReleaseCoverArt',
+  description: `An object containing a list of the cover art images for a
+release obtained from the [Cover Art Archive](https://musicbrainz.org/doc/Cover_Art_Archive),
+as well as a summary of what artwork is available.`,
+  fields: () => ({
+    front: {
+      type: URLString,
+      description: `The URL of an image depicting the album cover or “main
+front” of the release, i.e. the front of the packaging of the audio recording
+(or in the case of a digital release, the image associated with it in a digital
+media store).
+
+In the MusicBrainz schema, this field is a Boolean value indicating the presence
+of a front image, whereas here the value is the URL for the image itself if one
+exists. You can check for null if you just want to determine the presence of an
+image.`,
+      args: { size },
+      resolve: resolveImage
+    },
+    back: {
+      type: URLString,
+      description: `The URL of an image depicting the “main back” of the
+release, i.e. the back of the packaging of the audio recording.
+
+In the MusicBrainz schema, this field is a Boolean value indicating the presence
+of a back image, whereas here the value is the URL for the image itself. You can
+check for null if you just want to determine the presence of an image.`,
+      args: { size },
+      resolve: resolveImage
+    },
+    images: {
+      type: new GraphQLList(CoverArtImage),
+      description: `A list of images depicting the different sides and surfaces
+of a release’s media and packaging.`,
+      resolve: createFallbackResolver((coverArt, args, { loaders }) => {
+        if (coverArt.count === 0) {
+          return []
+        }
+        return loaders.coverArt.load(['release', coverArt._release])
+          .then(coverArt => coverArt.images)
+      })
+    },
+    artwork: {
+      type: new GraphQLNonNull(GraphQLBoolean),
+      description: 'Whether there is artwork present for this release.',
+      resolve: createFallbackResolver(coverArt => coverArt.images.length > 0)
+    },
+    darkened: {
+      type: new GraphQLNonNull(GraphQLBoolean),
+      description: `Whether the Cover Art Archive has received a take-down
+request for this release’s artwork, disallowing new uploads.`,
+      resolve: createFallbackResolver((coverArt, args, { loaders }) => {
+        return loaders.lookup.load(['release', coverArt._release])
+          .then(release => release['cover-art-archive'].darkened)
+      })
+    },
+    count: {
+      type: new GraphQLNonNull(GraphQLInt),
+      description: 'The number of artwork images present for this release.',
+      resolve: createFallbackResolver(coverArt => coverArt.images.length)
+    },
+    release: createReleaseField()
+  })
+})
+
+export const ReleaseGroupCoverArt = new GraphQLObjectType({
+  name: 'ReleaseGroupCoverArt',
+  description: `An object containing the cover art for a release group obtained
+from the [Cover Art Archive](https://musicbrainz.org/doc/Cover_Art_Archive). For
+release groups, just the front cover of particular release will be selected.`,
+  fields: () => ({
+    front: {
+      type: URLString,
+      description: `The URL of an image depicting the album cover or “main
+front” of a release in the release group, i.e. the front of the packaging of the
+audio recording (or in the case of a digital release, the image associated with
+it in a digital media store).`,
+      args: { size },
+      resolve: resolveImage
+    },
+    images: {
+      type: new GraphQLList(CoverArtImage),
+      description: `A list of images returned by the [Cover Art
+Archive](https://musicbrainz.org/doc/Cover_Art_Archive) for a release group. A
+particular release’s front image will be included in the list, and likely no
+others, even if other images are available.`
+    },
+    artwork: {
+      type: new GraphQLNonNull(GraphQLBoolean),
+      description: 'Whether there is artwork present for this release group.',
+      resolve: createFallbackResolver(coverArt => coverArt.images.length > 0)
+    },
+    release: createReleaseField()
+  })
+})

src/types/enums.js

@@ -39,6 +39,29 @@ distinctive name.`,
   }
 })
 
+export const CoverArtImageSize = new GraphQLEnumType({
+  name: 'CoverArtImageSize',
+  description: `The image sizes that may be requested at the [Cover Art
+Archive](https://musicbrainz.org/doc/Cover_Art_Archive).`,
+  values: {
+    SMALL: {
+      name: 'Small',
+      description: 'A maximum dimension of 250px.',
+      value: 250
+    },
+    LARGE: {
+      name: 'Large',
+      description: 'A maximum dimension of 500px.',
+      value: 500
+    },
+    FULL: {
+      name: 'Full',
+      description: 'The image’s original dimensions, with no maximum.',
+      value: null
+    }
+  }
+})
+
 export const ReleaseStatus = new GraphQLEnumType({
   name: 'ReleaseStatus',
   description: `A type used to describe the status of releases, e.g. official,

src/types/release-group.js

@@ -1,6 +1,7 @@
 import { GraphQLObjectType, GraphQLList } from 'graphql/type'
 import Node from './node'
 import Entity from './entity'
+import { ReleaseGroupCoverArt } from './cover-art'
 import { DateType } from './scalars'
 import { ReleaseGroupType } from './enums'
 import {
@@ -58,6 +59,14 @@ e.g. album, single, soundtrack, compilation, etc. A release group can have a
       description: `Additional [types](https://musicbrainz.org/doc/Release_Group/Type)
 that apply to this release group.`
     }),
+    coverArt: {
+      type: ReleaseGroupCoverArt,
+      description: `The cover art for a release group, obtained from the [Cover
+Art Archive](https://musicbrainz.org/doc/Cover_Art_Archive).`,
+      resolve: (releaseGroup, args, { loaders }) => {
+        return loaders.coverArt.load(['release-group', releaseGroup.id])
+      }
+    },
     artists,
     releases,
     relationships,

src/types/release.js

@@ -1,8 +1,14 @@
-import { GraphQLObjectType, GraphQLString, GraphQLList } from 'graphql/type'
+import {
+  GraphQLObjectType,
+  GraphQLNonNull,
+  GraphQLString,
+  GraphQLList
+} from 'graphql/type'
 import Node from './node'
 import Entity from './entity'
 import { ASIN, DateType } from './scalars'
 import Media from './media'
+import { ReleaseCoverArt } from './cover-art'
 import { ReleaseStatus } from './enums'
 import ReleaseEvent from './release-event'
 import {
@@ -68,6 +74,19 @@ release has one. The most common types found on releases are 12-digit
 [UPCs](https://en.wikipedia.org/wiki/Universal_Product_Code) and 13-digit
 [EANs](https://en.wikipedia.org/wiki/International_Article_Number).`
     },
+    coverArt: {
+      type: new GraphQLNonNull(ReleaseCoverArt),
+      description: `A list and summary of the cover art images that are present
+for this release from the [Cover Art Archive](https://musicbrainz.org/doc/Cover_Art_Archive).`,
+      resolve: (release, args, { loaders }) => {
+        const coverArt = release['cover-art-archive']
+        if (coverArt) {
+          coverArt._release = release.id
+          return coverArt
+        }
+        return loaders.coverArt.load(['release', release.id])
+      }
+    },
     ...fieldWithID('status', {
       type: ReleaseStatus,
       description: 'The status describes how “official” a release is.'

test/api/client.js

@@ -0,0 +1,9 @@
+import test from 'ava'
+import Client from '../../src/api/client'
+
+test('parseErrorMessage() returns the body or status code', t => {
+  const client = new Client()
+  t.is(client.parseErrorMessage({ statusCode: 500 }, 'something went wrong'), 'something went wrong')
+  t.is(client.parseErrorMessage({ statusCode: 500 }, ''), '500')
+  t.is(client.parseErrorMessage({ statusCode: 404 }, {}), '404')
+})

test/api/cover-art-archive.js

@@ -0,0 +1,47 @@
+import test from 'ava'
+import { CoverArtArchiveError } from '../../src/api'
+import client from '../helpers/client/cover-art-archive'
+
+test('can retrieve a front image URL', t => {
+  return client.imageURL('release', '76df3287-6cda-33eb-8e9a-044b5e15ffdd', 'front')
+    .then(url => {
+      t.is(url, 'http://archive.org/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd-829521842.jpg')
+    })
+})
+
+test('can retrieve a back image URL', t => {
+  return client.imageURL('release', '76df3287-6cda-33eb-8e9a-044b5e15ffdd', 'back')
+    .then(url => {
+      t.is(url, 'http://archive.org/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd-5769317885.jpg')
+    })
+})
+
+test('can retrieve a list of release images', t => {
+  return client.images('release', '76df3287-6cda-33eb-8e9a-044b5e15ffdd')
+    .then(data => {
+      t.is(data.release, 'http://musicbrainz.org/release/76df3287-6cda-33eb-8e9a-044b5e15ffdd')
+      t.true(data.images.length >= 3)
+      data.images.forEach(image => {
+        t.true(image.approved)
+        t.truthy(image.image)
+        t.truthy(image.id)
+        t.truthy(image.thumbnails.small)
+        t.truthy(image.thumbnails.large)
+      })
+      t.true(data.images.some(image => image.front))
+      t.true(data.images.some(image => image.back))
+      t.true(data.images.some(image => image.types.indexOf('Front') !== -1))
+      t.true(data.images.some(image => image.types.indexOf('Back') !== -1))
+      t.true(data.images.some(image => image.types.indexOf('Medium') !== -1))
+    })
+})
+
+test('throws an error if given an invalid MBID', t => {
+  return t.throws(client.images('release', 'xyz'), CoverArtArchiveError)
+})
+
+test('uses the default error impementation if there is no HTML error', t => {
+  t.is(client.parseErrorMessage({ statusCode: 501 }, 'yikes'), 'yikes')
+  t.is(client.parseErrorMessage({ statusCode: 500 }, ''), '500')
+  t.is(client.parseErrorMessage({ statusCode: 404 }, null), '404')
+})

test/api/musicbrainz.js

@@ -1,6 +1,6 @@
 import test from 'ava'
-import MusicBrainz, { MusicBrainzError } from '../src/api'
+import MusicBrainz, { MusicBrainzError } from '../../src/api'
-import client from './helpers/client'
+import client from '../helpers/client/musicbrainz'
 
 test('getLookupURL() generates a lookup URL', t => {
   t.is(client.getLookupURL('artist', 'c8da2e40-bd28-4d4e-813a-bd2f51958ba8', {
@@ -62,3 +62,9 @@ test('rejects non-MusicBrainz errors', t => {
   const client = new MusicBrainz({ baseURL: '$!@#$' })
   t.throws(client.get('artist/5b11f4ce-a62d-471e-81fc-a69a8278c7da'), Error)
 })
+
+test('uses the default error impementation if there is no JSON error', t => {
+  t.is(client.parseErrorMessage({ statusCode: 501 }, 'yikes'), 'yikes')
+  t.is(client.parseErrorMessage({ statusCode: 500 }, {}), '500')
+  t.is(client.parseErrorMessage({ statusCode: 404 }, null), '404')
+})

test/fixtures/01f85d1b5c1e1c7ee9768df1f7529a89

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/index.json

test/fixtures/01f85d1b5c1e1c7ee9768df1f7529a89.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:37:47 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/index.json",
+    "access-control-allow-origin": "*",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release/76df3287-6cda-33eb-8e9a-044b5e15ffdd",
+  "time": 372,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/029740f01ae52e57fcaa1fbe44f3cc76

@@ -0,0 +1 @@
+{"images":[{"edit":41326273,"back":false,"approved":true,"comment":"","types":["Front"],"thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955061405-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955061405-500.jpg"},"front":true,"id":"14955061405","image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955061405.jpg"},{"approved":true,"back":true,"edit":41326275,"id":"14955062822","front":false,"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955062822.jpg","thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955062822-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955062822-500.jpg"},"comment":"","types":["Back","Spine"]},{"id":"14955064370","front":false,"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955064370.jpg","thumbnails":{"large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955064370-500.jpg","small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955064370-250.jpg"},"types":["Tray"],"comment":"","approved":true,"back":false,"edit":41326278},{"edit":41326288,"approved":true,"back":false,"thumbnails":{"large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955066041-500.jpg","small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955066041-250.jpg"},"comment":"","types":["Booklet"],"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955066041.jpg","id":"14955066041","front":false},{"edit":41326294,"back":false,"approved":true,"comment":"","types":["Booklet"],"thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955068047-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955068047-500.jpg"},"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955068047.jpg","front":false,"id":"14955068047"},{"front":false,"id":"14955069655","image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955069655.jpg","types":["Booklet"],"comment":"","thumbnails":{"large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955069655-500.jpg","small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955069655-250.jpg"},"back":false,"approved":true,"edit":41326297},{"approved":true,"back":false,"edit":41326303,"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955071842.jpg","id":"14955071842","front":false,"thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955071842-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955071842-500.jpg"},"comment":"","types":["Booklet"]},{"types":["Booklet"],"comment":"","thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955073836-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955073836-500.jpg"},"front":false,"id":"14955073836","image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955073836.jpg","edit":41326306,"back":false,"approved":true},{"edit":41326325,"back":false,"approved":true,"comment":"","types":["Booklet"],"thumbnails":{"large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955075724-500.jpg","small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955075724-250.jpg"},"front":false,"id":"14955075724","image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/14955075724.jpg"},{"edit":41538992,"approved":true,"back":false,"thumbnails":{"small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067760321-250.jpg","large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067760321-500.jpg"},"comment":"Sticker","types":["Sticker"],"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067760321.jpg","id":"15067760321","front":false},{"id":"15067761190","front":false,"image":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067761190.jpg","thumbnails":{"large":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067761190-500.jpg","small":"http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52/15067761190-250.jpg"},"comment":"CD","types":["Medium"],"approved":true,"back":false,"edit":41538996}],"release":"https://musicbrainz.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52"}

test/fixtures/029740f01ae52e57fcaa1fbe44f3cc76.headers

@@ -0,0 +1,27 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "application/json",
+    "content-length": "4829",
+    "last-modified": "Fri, 04 Nov 2016 08:01:44 GMT",
+    "connection": "keep-alive",
+    "etag": "\"581c4068-12dd\"",
+    "expires": "Tue, 20 Dec 2016 07:39:56 GMT",
+    "cache-control": "max-age=21600",
+    "accept-ranges": "bytes"
+  },
+  "url": "http://ia601203.us.archive.org:80/29/items/mbid-d5cdb7fd-c7e9-460a-9549-8a369655cc52/index.json",
+  "time": 155,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://archive.org/download/mbid-d5cdb7fd-c7e9-460a-9549-8a369655cc52/index.json",
+      "host": "ia601203.us.archive.org"
+    }
+  }
+}

test/fixtures/0362ca3081fd5d16d8e29846798296a0

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/index.json

test/fixtures/0362ca3081fd5d16d8e29846798296a0.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:55 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/index.json",
+    "access-control-allow-origin": "*",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19",
+  "time": 414,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/071ecc4967496ac9ff5c75bcb6faf549.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:37:47 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia802607.us.archive.org/32/items/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/index.json",
+  "time": 139,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/76df3287-6cda-33eb-8e9a-044b5e15ffdd",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/078ffa5f6640843175067e82b92da215.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:11 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "577",
+    "x-ratelimit-reset": "1482198012",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"0c725784e392aef95ce4df262002a059\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/3e2c779e-16e8-459e-8791-2da47a92dce6?fmt=json",
+  "time": 415,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/07a9f4ce4cc4639f8ec3d5c06a91b670.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia600509.us.archive.org/33/items/mbid-fb98043c-7ac8-4505-ba87-28576836a8d5/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-fb98043c-7ac8-4505-ba87-28576836a8d5/index.json",
+  "time": 178,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/fb98043c-7ac8-4505-ba87-28576836a8d5",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/17a054fb91109cd8b5a2d1a8c8ab3a4a.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:05 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "423",
+    "x-ratelimit-reset": "1482198006",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"3467a86d0b1b88d5eccfdd5223cf828a\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec?fmt=json",
+  "time": 518,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/1c31d4f3569dee83470ccf2948435447.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:37:46 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "132",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd/mbid-76df3287-6cda-33eb-8e9a-044b5e15ffdd-5769317885.jpg",
+    "access-control-allow-origin": "*",
+    "server": "d8b8a8eb2a2a"
+  },
+  "url": "http://coverartarchive.org:80/release/76df3287-6cda-33eb-8e9a-044b5e15ffdd/back",
+  "time": 385,
+  "request": {
+    "method": "HEAD",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "content-length": 0
+    }
+  }
+}

test/fixtures/1fd72722a40edf79ad5317b82116949d

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-533e14a8-519d-4f04-95e8-8a84833f26b1/index.json

test/fixtures/1fd72722a40edf79ad5317b82116949d.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-533e14a8-519d-4f04-95e8-8a84833f26b1/index.json",
+    "access-control-allow-origin": "*",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/533e14a8-519d-4f04-95e8-8a84833f26b1",
+  "time": 504,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/217d797211c26dc393ef44fbf1a1a37e.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia601208.us.archive.org/31/items/mbid-ee773571-6147-4bfd-8ea1-d666c4d4caef/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-ee773571-6147-4bfd-8ea1-d666c4d4caef/index.json",
+  "time": 149,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/ee773571-6147-4bfd-8ea1-d666c4d4caef",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/240fa01906160caef0ad74b8e2fe44f0.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:55 GMT",
+    "content-type": "application/json; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "541",
+    "x-ratelimit-reset": "1482197996",
+    "last-modified": "Tue, 20 Dec 2016 01:16:03 GMT",
+    "server": "Jetty(9.3.10.v20160621)",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release?query=You%20Want%20It%20Darker&fmt=json",
+  "time": 415,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/257742f1f5f07e90a7514808bc18977a

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>400 Bad Request</title>
+<h1>Bad Request</h1>
+<p>invalid MBID specified</p>

test/fixtures/257742f1f5f07e90a7514808bc18977a.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 400,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:37:47 GMT",
+    "content-type": "text/html",
+    "content-length": "138",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/xyz",
+  "time": 366,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/325850e36c752b826928e22ac481772a.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:58 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "203",
+    "x-ratelimit-reset": "1482197998",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"08dc9c7327d0e7a8b9ede6ae8509c80b\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19?fmt=json",
+  "time": 449,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/34ca10f44e5af073160c7b6adac60130.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia601203.us.archive.org/29/items/mbid-d5cdb7fd-c7e9-460a-9549-8a369655cc52/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-d5cdb7fd-c7e9-460a-9549-8a369655cc52/index.json",
+  "time": 356,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/d5cdb7fd-c7e9-460a-9549-8a369655cc52",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/363970b23b4aa02d9be42a6492f76ada.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:22 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "338",
+    "x-ratelimit-reset": "1482198022",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"c190811eaf16a29a562055fc038d682c\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/7ff98ba2-d865-49eb-8bbd-23dc9d60f21c?fmt=json",
+  "time": 400,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/37dafe8b4260600bbb8b2571ec4ac86c.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:05 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "422",
+    "x-ratelimit-reset": "1482198006",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"bc27197091616cb74bbc5128fb69a933\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/533e14a8-519d-4f04-95e8-8a84833f26b1?fmt=json",
+  "time": 410,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/39192d7783e3cbd103a64e37435860c8

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>404 Not Found</title>
+<h1>Not Found</h1>
+<p>No cover art found for release 29a43eb0-537d-4af1-8598-8b488c847f2e</p>

test/fixtures/39192d7783e3cbd103a64e37435860c8.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 404,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/html",
+    "content-length": "179",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/29a43eb0-537d-4af1-8598-8b488c847f2e",
+  "time": 506,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/3aaa80314ca3bb3404ab1a0b2be0da6a

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-7aa99236-67d1-4996-b5ec-f6a517653fbe/index.json

test/fixtures/3aaa80314ca3bb3404ab1a0b2be0da6a.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-7aa99236-67d1-4996-b5ec-f6a517653fbe/index.json",
+    "access-control-allow-origin": "*",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release/7aa99236-67d1-4996-b5ec-f6a517653fbe",
+  "time": 391,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/3d1ea2a773f49cdf17cf4256f5cde4bf.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia601204.us.archive.org/4/items/mbid-3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec/index.json",
+  "time": 158,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/3d67fb108e6729c1e1e31c4889191cc4.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:11 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "579",
+    "x-ratelimit-reset": "1482198012",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"dc7e6d284fbbe310adcd3da8b6a4b24e\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/22a1945f-185c-4d70-979e-f297b00b0c71?fmt=json",
+  "time": 414,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/3f24e4abb92f417cc6ee84b83d09c180

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>404 Not Found</title>
+<h1>Not Found</h1>
+<p>No cover art found for release b2d35202-f793-487f-b796-ad0f1882a777</p>

test/fixtures/3f24e4abb92f417cc6ee84b83d09c180.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 404,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html",
+    "content-length": "179",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "d8b8a8eb2a2a"
+  },
+  "url": "http://coverartarchive.org:80/release/b2d35202-f793-487f-b796-ad0f1882a777",
+  "time": 392,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/436bd8bd74ed540a37fcc9135ea97368.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:11 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "573",
+    "x-ratelimit-reset": "1482198012",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"f31d3255a73df98fcc757f99355ca3d9\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39?fmt=json",
+  "time": 419,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/4722e553ad2febf7e2c68d71f478a338

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>404 Not Found</title>
+<h1>Not Found</h1>
+<p>No cover art found for release 15c88cc0-30f5-4568-bac8-e577e3358023</p>

test/fixtures/4722e553ad2febf7e2c68d71f478a338.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 404,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:55 GMT",
+    "content-type": "text/html",
+    "content-length": "179",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release/15c88cc0-30f5-4568-bac8-e577e3358023",
+  "time": 434,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/49b42184abf656b320a7124347074075

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-32a863b3-a356-4873-8b74-c2039156cb68/index.json

test/fixtures/49b42184abf656b320a7124347074075.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-32a863b3-a356-4873-8b74-c2039156cb68/index.json",
+    "access-control-allow-origin": "*",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/32a863b3-a356-4873-8b74-c2039156cb68",
+  "time": 495,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/4d3b01cc6d5ab75031ffa9465320de11.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:16 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "217",
+    "x-ratelimit-reset": "1482198016",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"463f2bbcb3f8dfb7e98aea81f2672f23\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/1724b946-fde3-49e5-adec-5e3f62f14a53?fmt=json",
+  "time": 417,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/4fcb70e39045e968057c2ef8a75f9186.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:00 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "296",
+    "x-ratelimit-reset": "1482198000",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"913a1fe119084c569261937e14d21171\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/0832e770-e7e5-464c-9288-9c407a770842?fmt=json",
+  "time": 415,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/55e718a13ff7c5178cbb0116a1bd2cd6.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:49 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "548",
+    "x-ratelimit-reset": "1482197990",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"412565deba857fd28ed53fb04eba9e16\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/b84ee12a-09ef-421b-82de-0441a926375b?fmt=json",
+  "time": 467,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/59293eea29033071de7f98943c3b5b1f

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec/index.json

test/fixtures/59293eea29033071de7f98943c3b5b1f.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec/index.json",
+    "access-control-allow-origin": "*",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/3ee3723e-ed1e-4baa-a718-7f1d9ecb3bec",
+  "time": 513,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/59c56dc30ab4179d0ee155e799ed637a.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:00 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "302",
+    "x-ratelimit-reset": "1482198000",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"d62c1c90ac668a9d6a2b70547d7879ce\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/15c88cc0-30f5-4568-bac8-e577e3358023?fmt=json",
+  "time": 409,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/5d11ca0430a620cfab0f05264323a992

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>404 Not Found</title>
+<h1>Not Found</h1>
+<p>No cover art found for release 83dc341f-1854-4319-b008-b6a26709dab8</p>

test/fixtures/5d11ca0430a620cfab0f05264323a992.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 404,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/html",
+    "content-length": "179",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release/83dc341f-1854-4319-b008-b6a26709dab8",
+  "time": 465,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/600c519401f48c53791ce190cae3f561

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-ee773571-6147-4bfd-8ea1-d666c4d4caef/index.json

test/fixtures/600c519401f48c53791ce190cae3f561.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-ee773571-6147-4bfd-8ea1-d666c4d4caef/index.json",
+    "access-control-allow-origin": "*",
+    "server": "d6446ea62189"
+  },
+  "url": "http://coverartarchive.org:80/release/ee773571-6147-4bfd-8ea1-d666c4d4caef",
+  "time": 476,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/681f1edb476435e41fdb6ae48bd7e2f9

@@ -0,0 +1 @@
+{"images":[{"types":["Front","Booklet"],"front":true,"back":false,"edit":29753022,"image":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615474322.jpg","comment":"","approved":true,"id":"8615474322","thumbnails":{"large":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615474322-500.jpg","small":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615474322-250.jpg"}},{"types":["Medium"],"front":false,"back":false,"edit":29753069,"image":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615530709.jpg","comment":"","approved":true,"id":"8615530709","thumbnails":{"large":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615530709-500.jpg","small":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615530709-250.jpg"}},{"types":["Back","Spine"],"front":false,"back":true,"edit":29753023,"image":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615477106.jpg","comment":"","approved":true,"id":"8615477106","thumbnails":{"large":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615477106-500.jpg","small":"http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39/8615477106-250.jpg"}}],"release":"http://musicbrainz.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39"}

test/fixtures/681f1edb476435e41fdb6ae48bd7e2f9.headers

@@ -0,0 +1,27 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "application/json",
+    "content-length": "1380",
+    "last-modified": "Sun, 26 Oct 2014 03:00:42 GMT",
+    "connection": "keep-alive",
+    "etag": "\"544c63da-564\"",
+    "expires": "Tue, 20 Dec 2016 07:39:57 GMT",
+    "cache-control": "max-age=21600",
+    "accept-ranges": "bytes"
+  },
+  "url": "http://ia802605.us.archive.org:80/15/items/mbid-90a00dba-addb-4fdc-af2c-6fbb5d733c39/index.json",
+  "time": 93,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://archive.org/download/mbid-90a00dba-addb-4fdc-af2c-6fbb5d733c39/index.json",
+      "host": "ia802605.us.archive.org"
+    }
+  }
+}

test/fixtures/71097d26676d70389a9b76ea2061db4d

@@ -0,0 +1 @@
+See: http://archive.org/download/mbid-25fbfbb4-b1ee-4448-aadf-ae3bc2e2dd27/index.json

test/fixtures/71097d26676d70389a9b76ea2061db4d.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:54 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "86",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-25fbfbb4-b1ee-4448-aadf-ae3bc2e2dd27/index.json",
+    "access-control-allow-origin": "*",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release-group/f5093c06-23e3-404f-aeaa-40f72885ee3a",
+  "time": 383,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/725c9375e05c924c1e007b737cb42594

@@ -0,0 +1,4 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
+<title>404 Not Found</title>
+<h1>Not Found</h1>
+<p>No cover art found for release 1724b946-fde3-49e5-adec-5e3f62f14a53</p>

test/fixtures/725c9375e05c924c1e007b737cb42594.headers

@@ -0,0 +1,22 @@
+{
+  "statusCode": 404,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html",
+    "content-length": "179",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "server": "d8b8a8eb2a2a"
+  },
+  "url": "http://coverartarchive.org:80/release/1724b946-fde3-49e5-adec-5e3f62f14a53",
+  "time": 410,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/74e59908ce007e6c1904a9ea1772ebb6.headers

@@ -0,0 +1,24 @@
+{
+  "statusCode": 307,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:49 GMT",
+    "content-type": "text/plain; charset=utf-8",
+    "content-length": "133",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "location": "http://archive.org/download/mbid-b84ee12a-09ef-421b-82de-0441a926375b/mbid-b84ee12a-09ef-421b-82de-0441a926375b-13536418798.jpg",
+    "access-control-allow-origin": "*",
+    "server": "4b4c084fb141"
+  },
+  "url": "http://coverartarchive.org:80/release/b84ee12a-09ef-421b-82de-0441a926375b/back",
+  "time": 392,
+  "request": {
+    "method": "HEAD",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "coverartarchive.org",
+      "accept-encoding": "gzip, deflate",
+      "content-length": 0
+    }
+  }
+}

test/fixtures/7625f6228e21bb0a707d6284d29f6238.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:05 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "428",
+    "x-ratelimit-reset": "1482198006",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"d1bd4c0b88cef71df921aaf373ebec8b\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/29a43eb0-537d-4af1-8598-8b488c847f2e?fmt=json",
+  "time": 402,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/7ac42ecd7ad91d876c3c3202ce69efa6.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:05 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "430",
+    "x-ratelimit-reset": "1482198006",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"47fd9b0e0985095d4a5fb58e02ddb790\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/060dc665-af64-4e75-8e51-d74eda2ec957?fmt=json",
+  "time": 392,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/7c1ef1cb044aa69ddad7cd69db399a81.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia802605.us.archive.org/15/items/mbid-90a00dba-addb-4fdc-af2c-6fbb5d733c39/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-90a00dba-addb-4fdc-af2c-6fbb5d733c39/index.json",
+  "time": 185,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/90a00dba-addb-4fdc-af2c-6fbb5d733c39",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/82f8e5c9c0995affcb90ff13a0359856.headers

@@ -0,0 +1,25 @@
+{
+  "statusCode": 302,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:57 GMT",
+    "content-type": "text/html; charset=UTF-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "x-powered-by": "PHP/5.5.9-1ubuntu4.20",
+    "accept-ranges": "bytes",
+    "location": "http://ia902608.us.archive.org/12/items/mbid-533e14a8-519d-4f04-95e8-8a84833f26b1/index.json"
+  },
+  "url": "http://archive.org:80/download/mbid-533e14a8-519d-4f04-95e8-8a84833f26b1/index.json",
+  "time": 202,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://coverartarchive.org/release/533e14a8-519d-4f04-95e8-8a84833f26b1",
+      "host": "archive.org"
+    }
+  }
+}

test/fixtures/8417827908807fd6dda52450c6e094c6.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:39:58 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "200",
+    "x-ratelimit-reset": "1482197998",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"43924c0dd2c3e691bc33bebc8ddc9268\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/3d354599-d9d4-44a8-9584-37e3b0238871?fmt=json",
+  "time": 416,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/851fadff7981d6862cc045eea0a822e3

@@ -0,0 +1 @@
+{"release":"https://musicbrainz.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19","images":[{"id":"14693820293","front":true,"image":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/14693820293.jpg","thumbnails":{"small":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/14693820293-250.jpg","large":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/14693820293-500.jpg"},"types":["Front"],"comment":"","approved":true,"back":false,"edit":40831187},{"thumbnails":{"large":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029120792-500.jpg","small":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029120792-250.jpg"},"types":["Back","Spine"],"comment":"","image":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029120792.jpg","id":"15029120792","front":false,"edit":41462768,"approved":true,"back":true},{"edit":41462773,"approved":true,"back":false,"thumbnails":{"small":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029124666-250.jpg","large":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029124666-500.jpg"},"types":["Medium"],"comment":"","image":"http://coverartarchive.org/release/dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/15029124666.jpg","id":"15029124666","front":false}]}

test/fixtures/851fadff7981d6862cc045eea0a822e3.headers

@@ -0,0 +1,27 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "server": "nginx/1.4.6 (Ubuntu)",
+    "date": "Tue, 20 Dec 2016 01:39:56 GMT",
+    "content-type": "application/json",
+    "content-length": "1383",
+    "last-modified": "Sun, 06 Nov 2016 10:02:39 GMT",
+    "connection": "keep-alive",
+    "etag": "\"581effbf-567\"",
+    "expires": "Tue, 20 Dec 2016 07:39:56 GMT",
+    "cache-control": "max-age=21600",
+    "accept-ranges": "bytes"
+  },
+  "url": "http://ia801508.us.archive.org:80/17/items/mbid-dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/index.json",
+  "time": 293,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json",
+      "referer": "http://archive.org/download/mbid-dd15903e-0ee7-45ec-aba1-2fc7b3a44e19/index.json",
+      "host": "ia801508.us.archive.org"
+    }
+  }
+}

test/fixtures/85b25c8d456ebee45124282fee2ce040.headers

@@ -0,0 +1,29 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 20 Dec 2016 01:40:16 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "transfer-encoding": "chunked",
+    "connection": "keep-alive",
+    "keep-alive": "timeout=15",
+    "vary": "Accept-Encoding",
+    "x-ratelimit-limit": "700",
+    "x-ratelimit-remaining": "224",
+    "x-ratelimit-reset": "1482198016",
+    "server": "Plack::Handler::Starlet",
+    "etag": "W/\"72d2983f2989ac6c7d1e5404726717fe\"",
+    "access-control-allow-origin": "*",
+    "content-encoding": "gzip"
+  },
+  "url": "http://musicbrainz.org:80/ws/2/release/83dc341f-1854-4319-b008-b6a26709dab8?fmt=json",
+  "time": 414,
+  "request": {
+    "method": "GET",
+    "headers": {
+      "User-Agent": "graphbrainz/4.5.0 ( https://github.com/exogen/graphbrainz )",
+      "host": "musicbrainz.org",
+      "accept-encoding": "gzip, deflate",
+      "accept": "application/json"
+    }
+  }
+}

test/fixtures/85fe9ce7ea1df73ed9a47c34a9ab639a

@@ -0,0 +1 @@
+{"release":"https://musicbrainz.org/release/ee773571-6147-4bfd-8ea1-d666c4d4caef","images":[{"comment":"","types":["Front"],"thumbnails":{"large":"http://coverartarchive.org/release/ee773571-6147-4bfd-8ea1-d666c4d4caef/14352438517-500.jpg","small":"http://coverartarchive.org/release/ee773571-6147-4bfd-8ea1-d666c4d4caef/14352438517-250.jpg"},"image":"http://coverartarchive.org/release/ee773571-6147-4bfd-8ea1-d666c4d4caef/14352438517.jpg","front":true,"id":"14352438517","edit":40179297,"back":false,"approved":true}]}