diff --git a/.gitignore b/.gitignore
index b754965..e2cf956 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@
 MANIFEST
 build/
 cover/
+coverage/
 coverage.xml
 dist/
 docs/_build/
diff --git a/.travis.yml b/.travis.yml
index 5ce0d3d..c1749cf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,7 @@ python:
 env:
   - TOX_ENV=py27
   - TOX_ENV=flake8
+  - TOX_ENV=test
   - TOX_ENV=eslint
   - TOX_ENV=csslint
   - TOX_ENV=tidy
@@ -19,4 +20,6 @@ script:
   - "tox -e $TOX_ENV"
 
 after_success:
-  - "if [ $TOX_ENV == 'py27' ]; then pip install coveralls; coveralls; fi"
+  # TODO: find a way to combine .py and .js coverage reports.
+  # - "if [ $TOX_ENV == 'py27' ]; then pip install coveralls; coveralls; fi"
+  - "if [ $TOX_ENV == 'test' ]; then cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js; fi"
diff --git a/karma.conf.js b/karma.conf.js
new file mode 100644
index 0000000..6104b24
--- /dev/null
+++ b/karma.conf.js
@@ -0,0 +1,81 @@
+// Karma configuration
+
+module.exports = function (config) {
+    config.set({
+
+        // base path that will be used to resolve all patterns (eg. files, exclude)
+        basePath: '',
+
+        // frameworks to use
+        // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
+        frameworks: ['browserify', 'mocha'],
+
+        // list of files / patterns to load in the browser
+        files: [
+            'mopidy_musicbox_webclient/static/vendors/**/*.js',
+            // TODO: can remove the next line once JavaScript codebase has been modularized.
+            'mopidy_musicbox_webclient/static/js/**/*.js',
+            'tests/**/test_*.js'
+        ],
+
+        // list of files to exclude
+        exclude: [
+        ],
+
+        // preprocess matching files before serving them to the browser
+        // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
+        preprocessors: {
+            'tests/**/test_*.js': [ 'browserify' ],
+            'mopidy_musicbox_webclient/static/js/**/*.js': ['coverage']
+        },
+
+        // test results reporter to use
+        // possible values: 'dots', 'progress'
+        // available reporters: https://npmjs.org/browse/keyword/karma-reporter
+        reporters: ['progress', 'coverage'],
+
+        // web server port
+        port: 9876,
+
+        // enable / disable colors in the output (reporters and logs)
+        colors: true,
+
+        // level of logging
+        // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
+        logLevel: config.LOG_INFO,
+
+        // enable / disable watching file and executing tests whenever any file changes
+        autoWatch: false,
+
+        // start these browsers
+        // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
+        browsers: ['PhantomJS'],
+
+        // Continuous Integration mode
+        // if true, Karma captures browsers, runs the tests and exits
+        singleRun: true,
+
+        // Concurrency level
+        // how many browser should be started simultaneous
+        concurrency: Infinity,
+
+        // add additional browserify configuration properties here
+        // such as transform and/or debug=true to generate source maps
+        browserify: {
+            debug: true,
+            transform: [
+                'babelify',
+                ['browserify-istanbul', { instrumenter: require('isparta') }]
+            ]
+        },
+
+        coverageReporter: {
+            // specify a common output directory
+            dir: 'coverage/',
+            reporters: [
+                { type: 'lcov', subdir: '.' },
+                { type: 'text'}
+            ]
+        }
+    })
+}
diff --git a/mopidy_musicbox_webclient/static/js/gui.js b/mopidy_musicbox_webclient/static/js/gui.js
index 104732e..7eff64c 100644
--- a/mopidy_musicbox_webclient/static/js/gui.js
+++ b/mopidy_musicbox_webclient/static/js/gui.js
@@ -128,7 +128,7 @@ function setSongInfo (data) {
     }
     if (data.track.album && data.track.album.name) {
         $('#modalalbum').html('<a href="#" onclick="return showAlbum(\'' + data.track.album.uri + '\');">' + data.track.album.name + '</a>')
-        getCover(data.track.uri, '#infocover, #controlspopupimage', 'extralarge')
+        coverArt.getCover(data.track.uri, '#infocover, #controlspopupimage', 'extralarge')
     } else {
         $('#modalalbum').html('')
         $('#infocover').attr('src', 'images/default_cover.png')
diff --git a/mopidy_musicbox_webclient/static/js/images.js b/mopidy_musicbox_webclient/static/js/images.js
index 5c16f18..0a1b531 100644
--- a/mopidy_musicbox_webclient/static/js/images.js
+++ b/mopidy_musicbox_webclient/static/js/images.js
@@ -5,88 +5,106 @@
 API_KEY = 'b6d34c3af91d62ab0ae00ab1b6fa8733'
 API_SECRET = '2c631802c2285d5d5d1502462fe42a2b'
 
-var fmcache
-var lastfm
-
-$(window).load(function () {
-    // create a Cache object
-    fmcache = new LastFMCache()
-    // create a LastFM object
-    lastfm = new LastFM({
+var coverArt = {
+    fmcache: new LastFMCache(),
+    lastfm: new LastFM({
         apiKey: API_KEY,
         apiSecret: API_SECRET,
-        cache: fmcache
-    })
-})
+        cache: this.fmcache
+    }),
 
-function getCover (uri, images, size) {
-    var defUrl = 'images/default_cover.png'
-    $(images).attr('src', defUrl)
-    if (!uri) {
-        return
-    }
-
-    mopidy.library.getImages({'uris': [uri]}).then(function (imageResults) {
-        var uri = Object.keys(imageResults)[0]
-        if (imageResults[uri].length > 0) {
-            $(images).attr('src', imageResults[uri][0].uri)
-        } else {
-            // Also check deprecated 'album.images' in case backend does not
-            // implement mopidy.library.getImages yet...
-            getCoverFromAlbum(uri, images, size)
+    getCover: function (uri, images, size) {
+        var defUrl = 'images/default_cover.png'
+        $(images).attr('src', defUrl)
+        if (!uri) {
+            return
         }
-    })
-}
+        mopidy.library.getImages({'uris': [uri]}).then(function (imageResults) {
+            var uri = Object.keys(imageResults)[0]
+            if (imageResults[uri].length > 0) {
+                $(images).attr('src', imageResults[uri][0].uri)
+            } else {
+                // Also check deprecated 'album.images' in case backend does not
+                // implement mopidy.library.getImages yet...
+                coverArt.getCoverFromAlbum(uri, images, size)
+            }
+        })
+    },
 
-// Note that this approach has been deprecated in Mopidy
-// TODO: Remove when Mopidy no longer supports getting images
-//       with 'album.images'.
-function getCoverFromAlbum (uri, images, size) {
-    mopidy.library.lookup({'uris': [uri]}).then(function (resultDict) {
-        var uri = Object.keys(resultDict)[0]
-        var track = resultDict[uri][0]
-        if (track.album && track.album.images && (track.album.images.length > 0)) {
-            $(images).attr('src', track.album.images[0])
-        } else {
-            // Fallback to last.fm
-            getCoverFromLastFm(track, images, size)
+    // Note that this approach has been deprecated in Mopidy
+    // TODO: Remove when Mopidy no longer supports getting images
+    //       with 'album.images'.
+    getCoverFromAlbum: function (uri, images, size) {
+        var defUrl = 'images/default_cover.png'
+        $(images).attr('src', defUrl)
+        if (!uri) {
+            return
         }
-    })
-}
+        mopidy.library.lookup({'uris': [uri]}).then(function (resultDict) {
+            var uri = Object.keys(resultDict)[0]
+            var track = resultDict[uri][0]
+            if (track && track.album && track.album.images && track.album.images.length > 0) {
+                $(images).attr('src', track.album.images[0])
+            } else if (track && (track.album || track.artist)) {
+                // Fallback to last.fm
+                coverArt.getCoverFromLastFm(track, images, size)
+            } else {
+                return
+            }
+        })
+    },
 
-function getCoverFromLastFm (track, images, size) {
-    var defUrl = 'images/default_cover.png'
-    if (!(track.album || track.artist)) {
-        return
-    }
-    var albumname = track.album.name || ''
-    var artistname = ''
-    if (track.album.artists && (track.album.artists.length > 0)) {
-        // First look for the artist in the album
-        artistname = track.album.artists[0].name
-    } else if (track.artists && (track.artists.length > 0)) {
-        // Fallback to using artists for specific track
-        artistname = track.artists[0].name
-    }
+    getCoverFromLastFm: function (track, images, size) {
+        var defUrl = 'images/default_cover.png'
+        $(images).attr('src', defUrl)
+        if (!track || !(track.album || track.artists)) {
+            return
+        }
+        var albumname = (track.album && track.album.name) ? track.album.name : ''
+        var artistname = ''
+        if (track.album && track.album.artists && track.album.artists.length > 0) {
+            // First look for the artist in the album
+            artistname = track.album.artists[0].name
+        } else if (track.artists && (track.artists.length > 0)) {
+            // Fallback to using artists for specific track
+            artistname = track.artists[0].name
+        }
 
-    lastfm.album.getInfo({artist: artistname, album: albumname},
-        { success: function (data) {
+        this.lastfm.album.getInfo({artist: artistname, album: albumname}, {success: function (data) {
             for (var i = 0; i < data.album.image.length; i++) {
                 if (data.album.image[i].size === size) {
                     $(images).attr('src', data.album.image[i]['#text'] || defUrl)
                 }
             }
+        }, error: function (code, message) {
+            console.log('Error retrieving album info from last.fm', code, message)
+        }})
+    },
+
+    getArtistImage: function (artist, images, size) {
+        var defUrl = 'images/user_24x32.png'
+        $(images).attr('src', defUrl)
+        if (!artist || artist.length === 0) {
+            return
         }
-    }, $(images).attr('src', defUrl))
+        this.lastfm.artist.getInfo({artist: artist}, {success: function (data) {
+            for (var i = 0; i < data.artist.image.length; i++) {
+                if (data.artist.image[i].size === size) {
+                    $(images).attr('src', data.artist.image[i]['#text'] || defUrl)
+                }
+            }
+        }, error: function (code, message) {
+            console.log('Error retrieving artist info from last.fm', code, message)
+        }})
+    }
 }
 
-function getArtistImage (nwartist, image, size) {
-    var defUrl = 'images/user_24x32.png'
-    lastfm.artist.getInfo({artist: nwartist}, {success: function (data) {
-        for (var i = 0; i < data.artist.image.length; i++) {
-            if (data.artist.image[i].size === size) {
-                $(image).attr('src', data.artist.image[i]['#text'] || defUrl)
-            }
-        }
-    }}, $(images).attr('src', defUrl))
+$(document).ready(coverArt.init)
+
+// TODO: Remove this once JavaScript codebase has been completely modularized
+//       in favour of bundling everything using 'browserify'.
+if (typeof exports !== 'undefined') {
+    if (typeof module !== 'undefined' && module.exports) {
+        module.exports = coverArt
+    }
 }
diff --git a/mopidy_musicbox_webclient/static/js/process_ws.js b/mopidy_musicbox_webclient/static/js/process_ws.js
index e4228af..4c0d287 100644
--- a/mopidy_musicbox_webclient/static/js/process_ws.js
+++ b/mopidy_musicbox_webclient/static/js/process_ws.js
@@ -220,7 +220,7 @@ function processCurrentPlaylist (resultArr) {
 function processArtistResults (resultArr) {
     if (!resultArr || (resultArr.length === 0)) {
         $('#h_artistname').text('Artist not found...')
-        getCover('', '#artistviewimage, #artistpopupimage', 'extralarge')
+        coverArt.getCover('', '#artistviewimage, #artistpopupimage', 'extralarge')
         showLoading(false)
         return
     }
@@ -239,7 +239,7 @@ function processArtistResults (resultArr) {
 function processAlbumResults (resultArr) {
     if (!resultArr || (resultArr.length === 0)) {
         $('#h_albumname').text('Album not found...')
-        getCover('', '#albumviewcover, #coverpopupimage', 'extralarge')
+        coverArt.getCover('', '#albumviewcover, #coverpopupimage', 'extralarge')
         showLoading(false)
         return
     }
@@ -252,6 +252,6 @@ function processAlbumResults (resultArr) {
     $('#h_albumartist').html(artistname)
     $('#coverpopupalbumname').html(albumname)
     $('#coverpopupartist').html(artistname)
-    getCover(resultArr[0].uri, '#albumviewcover, #coverpopupimage', 'extralarge')
+    coverArt.getCover(resultArr[0].uri, '#albumviewcover, #coverpopupimage', 'extralarge')
     showLoading(false)
 }
diff --git a/mopidy_musicbox_webclient/static/js/progress_timer.js b/mopidy_musicbox_webclient/static/js/progress_timer.js
index 0b371c7..00ff6e9 100644
--- a/mopidy_musicbox_webclient/static/js/progress_timer.js
+++ b/mopidy_musicbox_webclient/static/js/progress_timer.js
@@ -1,5 +1,4 @@
 var progressTimer
-var progressElement = document.getElementById('trackslider')
 var positionNode = document.createTextNode('')
 var durationNode = document.createTextNode('')
 
@@ -13,8 +12,10 @@ var syncsLeft = MAX_SYNCS
 var synced = false
 var consecutiveSyncs = 0
 
-document.getElementById('songelapsed').appendChild(positionNode)
-document.getElementById('songlength').appendChild(durationNode)
+$(document).ready(function () {
+    $('#songelapsed').append(positionNode)
+    $('#songlength').append(durationNode)
+})
 
 function timerCallback (position, duration, isRunning) {
     updateTimers(position, duration, isRunning)
diff --git a/package.json b/package.json
index ee6c8e3..97fb1ac 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,8 @@
     "test": "tests"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1",
-    "eslint": "eslint mopidy_musicbox_webclient/static/js/**.js",
+    "test": "karma start karma.conf.js",
+    "eslint": "eslint mopidy_musicbox_webclient/static/js/**/**.js tests/**/test_*.js",
     "csslint": "csslint mopidy_musicbox_webclient/static/css/**.css",
     "tidy": "node tidy.js"
   },
@@ -22,12 +22,32 @@
     "url": "https://github.com/pimusicbox/mopidy-musicbox-webclient/issues"
   },
   "devDependencies": {
-    "eslint": "latest",
-    "eslint-config-standard": "latest",
-    "eslint-plugin-standard": "latest",
-    "eslint-plugin-promise": "latest",
-    "csslint": "latest",
-    "tidy-html5": "latest"
+    "babelify": "^7.2.0",
+    "browserify": "^13.0.0",
+    "browserify-istanbul": "^2.0.0",
+    "chai": "^3.5.0",
+    "chai-as-promised": "^5.2.0",
+    "chai-jquery": "^2.0.0",
+    "chai-string": "^1.2.0",
+    "coveralls": "^2.11.8",
+    "csslint": "^0.10.0",
+    "eslint": "^2.3.0",
+    "eslint-config-standard": "^5.1.0",
+    "eslint-plugin-promise": "^1.1.0",
+    "eslint-plugin-standard": "^1.3.2",
+    "install": "^0.5.6",
+    "isparta": "^4.0.0",
+    "karma": "^0.13.22",
+    "karma-browserify": "^5.0.2",
+    "karma-cli": "^0.1.2",
+    "karma-coverage": "^0.5.5",
+    "karma-mocha": "^0.2.2",
+    "karma-phantomjs-launcher": "^1.0.0",
+    "mocha": "^2.4.5",
+    "phantomjs-prebuilt": "^2.1.5",
+    "sinon": "^1.17.3",
+    "tidy-html5": "latest",
+    "watchify": "^3.7.0"
   },
   "homepage": "https://github.com/pimusicbox/mopidy-musicbox-webclient#readme"
 }
diff --git a/tests/test_images.js b/tests/test_images.js
new file mode 100644
index 0000000..8d52232
--- /dev/null
+++ b/tests/test_images.js
@@ -0,0 +1,201 @@
+var chai = require('chai')
+var should = chai.should()
+var expect = chai.expect
+var assert = chai.assert
+chai.use(require('chai-string'))
+chai.use(require('chai-jquery'))
+
+var sinon = require('sinon')
+
+var coverArt = require('../mopidy_musicbox_webclient/static/js/images.js')
+
+var images
+
+before(function () {
+    html =
+        '<span id="songelapsed" class="pull-left"></span>' +
+        '<span id="songlength" class="pull-right"></span>'
+    $(document).ready(function () {
+        $(document.body).add(html)
+    })
+    mopidy = sinon.stub(new Mopidy({callingConvention: 'by-position-or-by-name'}))
+    images = $('<img id="img_mock">')
+})
+
+describe('CoverArt', function () {
+    describe('#getCover()', function () {
+        beforeEach(function () {
+            $(images).removeAttr('src')
+        })
+
+        it('should use default image if no track URI is provided', function () {
+            coverArt.getCover('', images, '')
+            $(images).prop('src').should.endWith('images/default_cover.png')
+        })
+
+        it('should get image from Mopidy, if available', function () {
+            var getImagesResultMock = {'mock:track:uri': [{uri: 'mockImageUri'}]}
+            var library = { getImages: function () { return $.when(getImagesResultMock) } }
+            mopidy.library = library
+
+            var getImagesSpy = sinon.spy(mopidy.library, 'getImages')
+            coverArt.getCover('mock:track:uri', images, '')
+
+            assert(getImagesSpy.calledOnce)
+            $(images).prop('src').should.endWith('mockImageUri')
+        })
+
+        it('should fall back to retrieving image from deprecated track.album.images', function () {
+            var getImagesResultMock = {'mock:track:uri': []}
+            var lookupResultMock = {'mock:track:uri': [{album: {images: ['mockAlbumImageUri']}}]}
+            var library = {
+                getImages: function () { return $.when(getImagesResultMock) },
+                lookup: function () { return $.when(lookupResultMock) }
+            }
+            mopidy.library = library
+
+            var getImagesSpy = sinon.spy(mopidy.library, 'getImages')
+            var getCoverFromAlbumSpy = sinon.spy(coverArt, 'getCoverFromAlbum')
+
+            coverArt.getCover('mock:track:uri', images, '')
+
+            assert(getImagesSpy.calledOnce)
+            assert(getCoverFromAlbumSpy.calledOnce)
+        })
+    })
+
+    describe('#getCoverFromAlbum()', function () {
+        beforeEach(function () {
+            $(images).removeAttr('src')
+        })
+
+        it('should use default image if no track URI is provided', function () {
+            coverArt.getCoverFromAlbum('', images, '')
+            $(images).prop('src').should.endWith('images/default_cover.png')
+        })
+
+        it('should get image from Mopidy track.album.images, if available', function () {
+            var lookupResultMock = {'mock:track:uri': [{album: {images: ['mockAlbumImageUri']}}]}
+            var library = {
+                lookup: function () { return $.when(lookupResultMock) }
+            }
+            mopidy.library = library
+
+            var lookupSpy = sinon.spy(mopidy.library, 'lookup')
+            coverArt.getCoverFromAlbum('mock:track:uri', images, '')
+
+            assert(lookupSpy.calledOnce)
+            $(images).prop('src').should.endWith('mockAlbumImageUri')
+        })
+
+        it('should use default image if track.album or track.artist is not available', function () {
+            var lookupResultMock = {'mock:track:uri': []}
+            var library = {
+                lookup: function () { return $.when(lookupResultMock) }
+            }
+            mopidy.library = library
+
+            var lookupSpy = sinon.spy(mopidy.library, 'lookup')
+            coverArt.getCoverFromAlbum('mock:track:uri', images, '')
+
+            assert(lookupSpy.calledOnce)
+            $(images).prop('src').should.endWith('images/default_cover.png')
+        })
+
+        it('should fall back to retrieving image from last.fm if none provided by Mopidy', function () {
+            var lookupResultMock = {'mock:track:uri': [{album: {images: []}}]}
+            var library = {
+                lookup: function () { return $.when(lookupResultMock) }
+            }
+            mopidy.library = library
+
+            var getCoverFromLastFmSpy = sinon.spy(coverArt, 'getCoverFromLastFm')
+            coverArt.getCoverFromAlbum('mock:track:uri', images, '')
+
+            assert(getCoverFromLastFmSpy.calledOnce)
+        })
+    })
+
+    describe('#getCoverFromLastFm()', function () {
+        beforeEach(function () {
+            $(images).removeAttr('src')
+        })
+
+        it('should use default image if no track is provided', function () {
+            coverArt.getCoverFromLastFm(undefined, images, '')
+            $(images).prop('src').should.endWith('images/default_cover.png')
+        })
+
+        it('should fall back to using track artist if album artist is not available', function () {
+            var track = {artists: [{name: 'artistMock'}]}
+            var getInfoResultMock = {album: {image: []}}
+
+            var getInfoStub = sinon.stub(coverArt.lastfm.album, 'getInfo')
+            getInfoStub.returns($.when(getInfoResultMock))
+
+            coverArt.getCoverFromLastFm(track, images, '')
+            var args = getInfoStub.args
+            assert(args[0][0].artist === 'artistMock')
+            getInfoStub.restore()
+        })
+
+        it('should get album info from last.fm', function () {
+            var track = {album: {artists: [{name: 'albumMock'}]}}
+            var getInfoResultMock = {album: {image: [{'#text': 'mockAlbumImageUri', size: 'small'}]}}
+
+            var getInfoStub = sinon.stub(coverArt.lastfm.album, 'getInfo')
+            getInfoStub.yieldsTo('success', getInfoResultMock)
+
+            coverArt.getCoverFromLastFm(track, images, 'small')
+            $(images).prop('src').should.endWith('mockAlbumImageUri')
+            getInfoStub.restore()
+        })
+
+        it('should log errors', function () {
+            var track = {album: {artists: [{name: 'albumMock'}]}}
+            var getInfoStub = sinon.stub(coverArt.lastfm.album, 'getInfo')
+            getInfoStub.yieldsTo('error', 'code', 'message')
+
+            var consoleSpy = sinon.spy(console, 'log')
+            coverArt.getCoverFromLastFm(track, images, '')
+
+            assert(consoleSpy.calledOnce)
+            getInfoStub.restore()
+            consoleSpy.restore()
+        })
+    })
+
+    describe('#getArtistImage()', function () {
+        beforeEach(function () {
+            $(images).removeAttr('src')
+        })
+
+        it('should use default image if no artist is provided', function () {
+            coverArt.getArtistImage('', images, '')
+            $(images).prop('src').should.endWith('images/user_24x32.png')
+        })
+
+        it('should get artist info from last.fm', function () {
+            var getInfoResultMock = {artist: {image: [{'#text': 'mockArtistImageUri', size: 'small'}]}}
+
+            var getInfoStub = sinon.stub(coverArt.lastfm.artist, 'getInfo')
+            getInfoStub.yieldsTo('success', getInfoResultMock)
+
+            coverArt.getArtistImage('mockArtist', images, 'small')
+            $(images).prop('src').should.endWith('mockArtistImageUri')
+            getInfoStub.restore()
+        })
+
+        it('should log errors', function () {
+            var getInfoStub = sinon.stub(coverArt.lastfm.artist, 'getInfo')
+            getInfoStub.yieldsTo('error', 'code', 'message')
+
+            var consoleSpy = sinon.spy(console, 'log')
+
+            coverArt.getArtistImage('mockArtist', images, 'small')
+            assert(consoleSpy.calledOnce)
+            getInfoStub.restore()
+            consoleSpy.restore()
+        })
+    })
+})
diff --git a/tox.ini b/tox.ini
index 96a5099..b6a3ba3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, flake8, eslint, csslint, tidy
+envlist = py27, flake8, test, eslint, csslint, tidy
 
 [testenv]
 deps =
@@ -20,7 +20,17 @@ deps =
     flake8
     flake8-import-order
 skip_install = true
-commands = flake8 {posargs:mopidy_musicbox_webclient}
+commands = flake8 {posargs:mopidy_musicbox_webclient tests}
+
+[testenv:test]
+whitelist_externals =
+    /bin/bash
+deps =
+    nodeenv
+skip_install = true
+commands =
+    - nodeenv --prebuilt {toxworkdir}/node_env
+    bash -c '. {toxworkdir}/node_env/bin/activate; npm install; npm test'
 
 [testenv:eslint]
 whitelist_externals =