diff --git a/tests/lib/commit-to-version-test.js b/tests/lib/commit-to-version-test.js
index cfced0ed..5dba11f4 100644
--- a/tests/lib/commit-to-version-test.js
+++ b/tests/lib/commit-to-version-test.js
@@ -1,34 +1,32 @@
-'use strict'
+const fs = require('fs')
+const exec = require('child_process').exec
 
-var fs = require('fs')
-var exec = require('child_process').exec
-
-var nixt = require('nixt')
+const nixt = require('nixt')
 
 module.exports = function (t, message, version, code, name, cwd) {
-  t.test(name, function (t) {
+  t.test(name, (t) => {
     t.plan(3)
 
     nixt()
       .cwd(cwd)
       .env('CI', true)
       .env('npm_config_registry', 'http://127.0.0.1:4873/')
-      .exec('git commit --allow-empty -m "' + message + '"')
+      .exec(`git commit --allow-empty -m "${message}"`)
       .run('npm run prepublish')
       .code(code)
       .stdout(/semantic-release.js pre\n\nDetermining new version\n/m)
-      .end(function (err) {
+      .end((err) => {
         t.error(err, 'nixt')
 
-        var pkg = JSON.parse(fs.readFileSync(cwd + '/package.json'))
+        const pkg = JSON.parse(fs.readFileSync(`${cwd}/package.json`))
         t.is(pkg.version, version, 'version')
 
         if (code === 1) {
           return t.error(null, 'no publish')
         }
 
-        exec('npm publish --ignore-scripts', {cwd: cwd}, function (err) {
-          setTimeout(function () {
+        exec('npm publish --ignore-scripts', {cwd}, (err) => {
+          setTimeout(() => {
             t.error(err, 'publish')
           }, 300)
         })
diff --git a/tests/lib/create-module.js b/tests/lib/create-module.js
index 31725a69..b07efc47 100644
--- a/tests/lib/create-module.js
+++ b/tests/lib/create-module.js
@@ -1,16 +1,14 @@
-'use strict'
+const exec = require('child_process').exec
+const join = require('path').join
 
-var exec = require('child_process').exec
-var join = require('path').join
-
-var efh = require('error-first-handler')
-var defaults = require('lodash.defaults')
-var uid = require('nano-uid')()
+const efh = require('error-first-handler')
+const defaults = require('lodash.defaults')
+const uid = require('nano-uid')()
 
 module.exports = function (input) {
-  var cb = Array.prototype.pop.call(arguments)
-  uid.generate(5, efh(cb)(function (id) {
-    var pkg = defaults((typeof input === 'object' ? input : {}), {
+  const cb = Array.prototype.pop.call(arguments)
+  uid.generate(5, efh(cb)((id) => {
+    const pkg = defaults((typeof input === 'object' ? input : {}), {
       name: id,
       version: '0.0.0',
       scripts: {
@@ -23,18 +21,18 @@ module.exports = function (input) {
     })
 
     id = pkg.name
-    var cwd = join(__dirname, '../../.tmp/modules', id)
+    const cwd = join(__dirname, '../../.tmp/modules', id)
 
     exec(
-      'mkdir ' + cwd + ' && ' +
-      'cd ' + cwd + ' && ' +
-      'git init && ' +
-      'echo \'' + JSON.stringify(pkg, null, 2) + '\' >> package.json && ' +
-      'git add . && ' +
-      'git config user.email "integration@test" && ' +
-      'git config user.name "Integration Test" && ' +
-      'git commit -m "initial"'
-    , efh(cb)(function (stdout) {
+      `mkdir ${cwd} &&
+      cd ${cwd} &&
+      git init &&
+      echo '${JSON.stringify(pkg, null, 2)}' >> package.json &&
+      git add . &&
+      git config user.email "integration@test" &&
+      git config user.name "Integration Test" &&
+      git commit -m "initial"`
+    , efh(cb)((stdout) => {
       cb(null, id, cwd)
     }))
   }))
diff --git a/tests/lib/custom-analyzer.js b/tests/lib/custom-analyzer.js
index cd548e70..5964ae69 100644
--- a/tests/lib/custom-analyzer.js
+++ b/tests/lib/custom-analyzer.js
@@ -1,9 +1,7 @@
-'use strict'
-
 module.exports = function (commits) {
-  var type = null
+  let type = null
 
-  commits.every(function (commit) {
+  commits.every((commit) => {
     if (/FOO/.test(commit.message)) {
       type = 'major'
       return false
diff --git a/tests/lib/custom-release-notes.js b/tests/lib/custom-release-notes.js
index f9527d51..d6913c16 100644
--- a/tests/lib/custom-release-notes.js
+++ b/tests/lib/custom-release-notes.js
@@ -1,5 +1,3 @@
-'use strict'
-
 module.exports = function (cb) {
   cb(null, 'custom log')
 }
diff --git a/tests/lib/custom-verification.js b/tests/lib/custom-verification.js
index aae19461..48432356 100644
--- a/tests/lib/custom-verification.js
+++ b/tests/lib/custom-verification.js
@@ -1,5 +1,3 @@
-'use strict'
-
 module.exports = function (opts, cb) {
   cb(null, !(opts.commits.length % 2))
 }
diff --git a/tests/scenarios/custom-analyzer.js b/tests/scenarios/custom-analyzer.js
index 6a1f53be..078afa68 100644
--- a/tests/scenarios/custom-analyzer.js
+++ b/tests/scenarios/custom-analyzer.js
@@ -1,19 +1,17 @@
-'use strict'
+const path = require('path')
 
-var path = require('path')
+const efh = require('error-first-handler')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
+const commitToVersionTest = require('../lib/commit-to-version-test')
 
-var createModule = require('../lib/create-module')
-var commitToVersionTest = require('../lib/commit-to-version-test')
-
-test('custom-analyzer', function (t) {
+test('custom-analyzer', (t) => {
   createModule({
     release: {
       analyzer: path.join(__dirname, '../lib/custom-analyzer')
     }
-  }, efh()(function (name, cwd) {
+  }, efh()((name, cwd) => {
     commitToVersionTest(t, 'HO', '0.0.0', 1, 'abort publish w/o changes', cwd)
     commitToVersionTest(t, 'BAZ', '1.0.0', 0, 'release 1.0.0 if unpublished', cwd)
     commitToVersionTest(t, 'BAZ', '1.0.1', 0, 'bump patch for fix', cwd)
diff --git a/tests/scenarios/custom-verification.js b/tests/scenarios/custom-verification.js
index e9b9df88..a72ec7d7 100644
--- a/tests/scenarios/custom-verification.js
+++ b/tests/scenarios/custom-verification.js
@@ -1,20 +1,18 @@
-'use strict'
+const path = require('path')
 
-var path = require('path')
+const efh = require('error-first-handler')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-test('custom-verification', function (t) {
+test('custom-verification', (t) => {
   createModule({
     release: {
       verification: path.join(__dirname, '../lib/custom-verification')
     }
-  }, efh()(function (name, cwd) {
-    t.test('even commit count', function (t) {
+  }, efh()((name, cwd) => {
+    t.test('even commit count', (t) => {
       t.plan(1)
       nixt()
         .cwd(cwd)
@@ -23,12 +21,10 @@ test('custom-verification', function (t) {
         .exec('git commit --allow-empty -m "feat: commit"')
         .run('npm run prepublish')
         .code(0)
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
 
-    t.test('odd commit count', function (t) {
+    t.test('odd commit count', (t) => {
       t.plan(1)
       nixt()
         .cwd(cwd)
@@ -38,9 +34,7 @@ test('custom-verification', function (t) {
         .run('npm run prepublish')
         .code(1)
         .stdout(/Verification failed/)
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
   }))
 })
diff --git a/tests/scenarios/ignore.js b/tests/scenarios/ignore.js
index c92e063d..bae6fa30 100644
--- a/tests/scenarios/ignore.js
+++ b/tests/scenarios/ignore.js
@@ -1,15 +1,13 @@
-'use strict'
+const fs = require('fs')
 
-var fs = require('fs')
+const efh = require('error-first-handler')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-test('ignore', function (t) {
-  createModule(efh()(function (name, cwd) {
+test('ignore', (t) => {
+  createModule(efh()((name, cwd) => {
     ignoreTest(t, cwd, 'npm install', 'not doing anything when the module is installed')
     ignoreTest(t, cwd, 'npm i', 'not doing anything when the module is installed with abbrevd command')
     ignoreTest(t, cwd, 'npm link', 'not doing anything when the module is linked')
@@ -20,18 +18,18 @@ test('ignore', function (t) {
 })
 
 function ignoreTest (t, cwd, command, name) {
-  t.test(name, function (t) {
+  t.test(name, (t) => {
     t.plan(2)
 
-    var pkg = fs.readFileSync(cwd + '/package.json')
+    const pkg = String(fs.readFileSync(cwd + '/package.json'))
 
     nixt()
       .cwd(cwd)
       .run(command)
       .code(0)
       .stdout(/semantic-release.js pre\n$/m)
-      .end(function (err) {
-        t.is(pkg + '', fs.readFileSync(cwd + '/package.json') + '', 'package')
+      .end((err) => {
+        t.is(pkg, String(fs.readFileSync(`${cwd}/package.json`)), 'package')
         t.error(err, 'nixt')
       })
   })
diff --git a/tests/scenarios/postpublish.js b/tests/scenarios/postpublish.js
index 0f5096cc..227f483d 100644
--- a/tests/scenarios/postpublish.js
+++ b/tests/scenarios/postpublish.js
@@ -1,15 +1,13 @@
-'use strict'
+const path = require('path')
 
-var path = require('path')
+const efh = require('error-first-handler')
+const GitHubApi = require('github')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var GitHubApi = require('github')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-var github = new GitHubApi({
+const github = new GitHubApi({
   version: '3.0.0',
   port: 4343,
   protocol: 'http',
@@ -21,44 +19,40 @@ github.authenticate({
   token: '***'
 })
 
-test('postpublish', function (t) {
+test('postpublish', (t) => {
   createModule({
     version: '2.0.0',
     repository: {
       type: 'git',
       url: 'http://github.com/user/repo'
     }
-  }, efh()(function (name, cwd) {
-    var base = getBase(cwd)
+  }, efh()((name, cwd) => {
+    const base = getBase(cwd)
 
-    t.test('publish new version to github releases', function (t) {
+    t.test('publish new version to github releases', (t) => {
       t.plan(1)
 
       base.clone()
         .stdout(/semantic-release.js post\n\nGenerating changelog from.*\nParsed/m)
         .run('npm run postpublish')
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
 
-    t.test('publish new version (with detached HEAD) to github releases', function (t) {
+    t.test('publish new version (with detached HEAD) to github releases', (t) => {
       t.plan(1)
 
       base.clone()
         .stdout(/semantic-release.js post\n\nGenerating changelog from.*\nParsed/m)
         .exec('git checkout `git rev-parse HEAD`')
         .run('npm run postpublish')
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
 
-    t.test('correct data published', function (t) {
+    t.test('correct data published', (t) => {
       t.plan(4)
 
-      github.releases.getRelease({ owner: 'user', repo: 'repo', id: 1}, function (err, raw) {
-        var res = JSON.parse(raw)
+      github.releases.getRelease({ owner: 'user', repo: 'repo', id: 1}, (err, raw) => {
+        const res = JSON.parse(raw)
         t.error(err, 'github')
         t.is(res.tag_name, 'v2.0.0', 'version')
         t.is(res.author.login, 'user', 'user')
@@ -76,24 +70,22 @@ test('postpublish', function (t) {
     release: {
       notes: path.join(__dirname, '../lib/custom-release-notes')
     }
-  }, efh()(function (name, cwd) {
-    var base = getBase(cwd)
+  }, efh()((name, cwd) => {
+    const base = getBase(cwd)
 
-    t.test('publish new version (with custom notes) to github releases', function (t) {
+    t.test('publish new version (with custom notes) to github releases', (t) => {
       t.plan(1)
 
       base.clone()
         .run('npm run postpublish')
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
 
-    t.test('custom notes published', function (t) {
+    t.test('custom notes published', (t) => {
       t.plan(4)
 
-      github.releases.getRelease({ owner: 'user', repo: 'repo', id: 3}, function (err, raw) {
-        var res = JSON.parse(raw)
+      github.releases.getRelease({ owner: 'user', repo: 'repo', id: 3}, (err, raw) => {
+        const res = JSON.parse(raw)
         t.error(err, 'github')
         t.is(res.tag_name, 'v2.0.0', 'version')
         t.is(res.author.login, 'user', 'user')
diff --git a/tests/scenarios/prepublish.js b/tests/scenarios/prepublish.js
index fdaf6aea..32390411 100644
--- a/tests/scenarios/prepublish.js
+++ b/tests/scenarios/prepublish.js
@@ -1,13 +1,11 @@
-'use strict'
+const efh = require('error-first-handler')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
+const commitToVersionTest = require('../lib/commit-to-version-test')
 
-var createModule = require('../lib/create-module')
-var commitToVersionTest = require('../lib/commit-to-version-test')
-
-test('prepublish', function (t) {
-  createModule(efh()(function (name, cwd) {
+test('prepublish', (t) => {
+  createModule(efh()((name, cwd) => {
     commitToVersionTest(t, 'refactor: change', '0.0.0', 1, 'abort publish w/o changes', cwd)
     commitToVersionTest(t, 'fix: change', '1.0.0', 0, 'release 1.0.0 if unpublished', cwd)
     commitToVersionTest(t, 'fix: change', '1.0.1', 0, 'bump patch for fix', cwd)
diff --git a/tests/scenarios/publish.js b/tests/scenarios/publish.js
index e7901774..61636b86 100644
--- a/tests/scenarios/publish.js
+++ b/tests/scenarios/publish.js
@@ -1,12 +1,10 @@
-'use strict'
+const efh = require('error-first-handler')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-test('publish', function (t) {
+test('publish', (t) => {
   publishTest(t, 'npm publish', 'pre and post hooks work as a part of publish')
   publishTest(t, 'npm pub', 'pre and post hooks work as a part of publish with abbrevd command')
 
@@ -16,8 +14,8 @@ test('publish', function (t) {
         type: 'git',
         url: 'http://github.com/user/repo'
       }
-    }, efh()(function (name, cwd) {
-      t.test(testname, function (t) {
+    }, efh()((name, cwd) => {
+      t.test(testname, (t) => {
         t.plan(1)
 
         nixt()
@@ -29,9 +27,7 @@ test('publish', function (t) {
           .run(command)
           .code(1)
           .stdout(/Everything is alright/)
-          .end(function (err) {
-            t.error(err, 'nixt')
-          })
+          .end((err) => t.error(err, 'nixt'))
       })
     }))
   }
diff --git a/tests/scenarios/setup.js b/tests/scenarios/setup.js
index c82107b1..8910ff91 100644
--- a/tests/scenarios/setup.js
+++ b/tests/scenarios/setup.js
@@ -1,22 +1,20 @@
-'use strict'
+const join = require('path').join
+const readFile = require('fs').readFileSync
 
-var join = require('path').join
-var readFile = require('fs').readFileSync
+const efh = require('error-first-handler')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-test('setup', function (t) {
+test('setup', (t) => {
   createModule({
     repository: {},
     scripts: {
       postpublish: 'npm run gh-pages'
     }
-  }, efh()(function (name, cwd) {
-    t.test('setup "package.json"', function (t) {
+  }, efh()((name, cwd) => {
+    t.test('setup "package.json"', (t) => {
       t.plan(5)
 
       nixt()
@@ -24,10 +22,10 @@ test('setup', function (t) {
         .exec('git remote add origin git@github.com:user/repo.git')
         .run('../../../bin/semantic-release.js setup')
         .code(0)
-        .end(function (err) {
+        .end((err) => {
           t.error(err, 'nixt')
 
-          var pkg = JSON.parse(readFile(join(cwd, 'package.json')))
+          const pkg = JSON.parse(readFile(join(cwd, 'package.json')))
 
           t.is(pkg.version, '0.0.0-semantically-released', 'version')
           t.is(pkg.repository.url, 'https://github.com/user/repo', 'repo')
diff --git a/tests/scenarios/verify.js b/tests/scenarios/verify.js
index ab679b18..e6d8a191 100644
--- a/tests/scenarios/verify.js
+++ b/tests/scenarios/verify.js
@@ -1,41 +1,37 @@
-'use strict'
+const efh = require('error-first-handler')
+const nixt = require('nixt')
+const test = require('tap').test
 
-var efh = require('error-first-handler')
-var nixt = require('nixt')
-var test = require('tap').test
+const createModule = require('../lib/create-module')
 
-var createModule = require('../lib/create-module')
-
-test('verify', function (t) {
+test('verify', (t) => {
   createModule({
     repository: {},
     scripts: {
       prepublish: '../../../bin/semantic-release.js pre --no-token'
     }
-  }, efh()(function (name, cwd) {
-    t.test('verify package and options before publishing', function (t) {
+  }, efh()((name, cwd) => {
+    t.test('verify package and options before publishing', (t) => {
       t.plan(1)
       nixt()
         .cwd(cwd)
         .env('CI', true)
         .run('npm publish')
         .stderr(new RegExp(
-          'You must define a GitHub token\.\n' +
-          'You must define your GitHub "repository" inside the "package.json"\.\n' +
-          'You must define your "scripts" inside the "package.json"\.'
+`You must define a GitHub token\.
+You must define your GitHub "repository" inside the "package.json"\.
+You must define your "scripts" inside the "package.json"\.`
           , 'm'
         ))
         .code(1)
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
   }))
 
   createModule({
     version: '1.0.0-semantically-released'
-  }, efh()(function (name, cwd) {
-    t.test('not publishing placeholder versions', function (t) {
+  }, efh()((name, cwd) => {
+    t.test('not publishing placeholder versions', (t) => {
       t.plan(1)
 
       nixt()
@@ -43,9 +39,7 @@ test('verify', function (t) {
         .env('CI', true)
         .run('npm publish --semantic-release-rerun')
         .code(1)
-        .end(function (err) {
-          t.error(err, 'nixt')
-        })
+        .end((err) => t.error(err, 'nixt'))
     })
   }))
 })
diff --git a/tests/tap/npm-info.js b/tests/tap/npm-info.js
index ca3b8e25..841fc538 100644
--- a/tests/tap/npm-info.js
+++ b/tests/tap/npm-info.js
@@ -1,13 +1,11 @@
-'use strict'
+const test = require('tap').test
+const nock = require('nock')
 
-var test = require('tap').test
-var nock = require('nock')
+const npmInfo = require('../../dist/lib/npm-info.js')
 
-var npmInfo = require('../../dist/lib/npm-info.js')
+const registry = 'http://registry.npmjs.org/'
 
-var registry = 'http://registry.npmjs.org/'
-
-var defaultModule = {
+const defaultModule = {
   'dist-tags': {
     latest: '1.0.0'
   },
@@ -20,8 +18,8 @@ var defaultModule = {
 
 process.env.npm_config_registry = registry
 
-test('npm-info', function (t) {
-  var regMock = nock(registry, {
+test('npm-info', (t) => {
+  const regMock = nock(registry, {
     reqheaders: {
       'authorization': 'Bearer testtoken'
     }
@@ -31,17 +29,17 @@ test('npm-info', function (t) {
   .get('/@user%2Fmodule')
   .reply(200, defaultModule)
 
-  t.test('get unscoped module', function (t) {
+  t.test('get unscoped module', (t) => {
     t.plan(3)
-    npmInfo('express', function (err, info) {
+    npmInfo('express', (err, info) => {
       t.error(err, 'error')
       t.is(info.version, '1.0.0', 'version')
       t.is(info.gitHead, 'HEAD', 'gitHead')
     })
   })
-  t.test('get scoped module', function (t) {
+  t.test('get scoped module', (t) => {
     t.plan(3)
-    npmInfo('@user/module', function (err, info) {
+    npmInfo('@user/module', (err, info) => {
       t.error(err, 'error')
       t.is(info.version, '1.0.0', 'version')
       t.is(info.gitHead, 'HEAD', 'gitHead')