diff --git a/.eslintignore b/.eslintignore
index 7e21e213d..306105960 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -1,4 +1,6 @@
 build/
-test/
 example/
 helpers/
+lib/platform-shims/esm.mjs
+test/fixtures/**/**
+example.mjs
diff --git a/lib/platform-shims/browser.mjs b/lib/platform-shims/browser.mjs
index 5740a0fec..5bba14653 100644
--- a/lib/platform-shims/browser.mjs
+++ b/lib/platform-shims/browser.mjs
@@ -1,3 +1,4 @@
+/* eslint-disable no-unused-vars */
 'use strict';
 
 import cliui from 'https://unpkg.com/cliui@7.0.1/index.mjs'; // eslint-disable-line
@@ -44,6 +45,7 @@ export default {
     // exit is noop browser:
     exit: () => {},
     nextTick: cb => {
+      // eslint-disable-next-line no-undef
       window.setTimeout(cb, 1);
     },
     stdColumns: 80,
diff --git a/package.json b/package.json
index 292c02905..ceeaca2d2 100644
--- a/package.json
+++ b/package.json
@@ -71,14 +71,13 @@
     "rimraf": "^3.0.2",
     "rollup": "^2.23.0",
     "rollup-plugin-cleanup": "^3.1.1",
-    "standardx": "^7.0.0",
     "typescript": "^4.0.2",
     "which": "^2.0.0",
     "yargs-test-extends": "^1.0.1"
   },
   "scripts": {
     "fix": "gts fix && npm run fix:js",
-    "fix:js": "standardx --fix **/*.mjs && standardx --fix **/*.cjs && standardx --fix ./*.mjs && standardx --fix ./*.cjs",
+    "fix:js": "eslint . --ext cjs --ext mjs --ext js --fix",
     "posttest": "npm run check",
     "test": "c8 mocha ./test/*.cjs --require ./test/before.cjs --timeout=12000 --check-leaks",
     "test:esm": "c8 mocha ./test/esm/*.mjs --check-leaks",
@@ -90,7 +89,7 @@
     "build:cjs": "rollup -c rollup.config.cjs",
     "postbuild:cjs": "rimraf ./build/index.cjs.d.ts",
     "check": "gts lint && npm run check:js",
-    "check:js": "standardx **/*.mjs && standardx **/*.cjs && standardx ./*.mjs && standardx ./*.cjs",
+    "check:js": "eslint . --ext cjs --ext mjs --ext js",
     "clean": "gts clean"
   },
   "repository": {
@@ -98,14 +97,6 @@
     "url": "https://github.com/yargs/yargs.git"
   },
   "homepage": "https://yargs.js.org/",
-  "standardx": {
-    "ignore": [
-      "build",
-      "helpers",
-      "**/example/**",
-      "**/platform-shims/esm.mjs"
-    ]
-  },
   "keywords": [
     "argument",
     "args",
diff --git a/test/command.cjs b/test/command.cjs
index ab284f570..5a3c01269 100644
--- a/test/command.cjs
+++ b/test/command.cjs
@@ -1,5 +1,6 @@
-'use strict';
 /* global describe, it, beforeEach */
+/* eslint-disable no-unused-vars */
+'use strict';
 const yargs = require('../index.cjs');
 const expect = require('chai').expect;
 const checkOutput = require('./helpers/utils.cjs').checkOutput;
diff --git a/test/completion.cjs b/test/completion.cjs
index cf52d299a..a37709d75 100644
--- a/test/completion.cjs
+++ b/test/completion.cjs
@@ -1,5 +1,6 @@
 'use strict';
 /* global describe, it, before, beforeEach, after */
+/* eslint-disable no-unused-vars */
 const checkUsage = require('./helpers/utils.cjs').checkOutput;
 const yargs = require('../index.cjs');
 
diff --git a/test/deno/platform-shim.test.ts b/test/deno/platform-shim.test.ts
index aca9a3013..4ecb3c235 100644
--- a/test/deno/platform-shim.test.ts
+++ b/test/deno/platform-shim.test.ts
@@ -1,22 +1,30 @@
 /* global Deno */
 
-import {
-  assertEquals
-} from 'https://deno.land/std/testing/asserts.ts'
-import shim from '../../lib/platform-shims/deno.ts'
+import {assertEquals} from 'https://deno.land/std/testing/asserts.ts';
+import shim from '../../lib/platform-shims/deno.ts';
 
 // y18n.
 Deno.test('__ behaves like sprintf', () => {
-  const str = shim.y18n.__('hello %s, goodnight %s', 'world', 'moon')
-  assertEquals(str, 'hello world, goodnight moon')
-})
+  const str = shim.y18n.__('hello %s, goodnight %s', 'world', 'moon');
+  assertEquals(str, 'hello world, goodnight moon');
+});
 
 Deno.test('__n uses first string if singular', () => {
-  const str = shim.y18n.__n('Missing required argument: %s', 'Missing required arguments: %s', 1, 'foo, bar')
-  assertEquals(str, 'Missing required argument: foo, bar')
-})
+  const str = shim.y18n.__n(
+    'Missing required argument: %s',
+    'Missing required arguments: %s',
+    1,
+    'foo, bar'
+  );
+  assertEquals(str, 'Missing required argument: foo, bar');
+});
 
 Deno.test('__n uses second string if plural', () => {
-  const str = shim.y18n.__n('Missing required argument: %s', 'Missing required arguments: %s', 2, 'foo, bar')
-  assertEquals(str, 'Missing required arguments: foo, bar')
-})
+  const str = shim.y18n.__n(
+    'Missing required argument: %s',
+    'Missing required arguments: %s',
+    2,
+    'foo, bar'
+  );
+  assertEquals(str, 'Missing required arguments: foo, bar');
+});
diff --git a/test/deno/yargs.test.ts b/test/deno/yargs.test.ts
index 895b6f011..01264c747 100644
--- a/test/deno/yargs.test.ts
+++ b/test/deno/yargs.test.ts
@@ -2,43 +2,49 @@
 
 import {
   assertEquals,
-  assertMatch
-} from 'https://deno.land/std/testing/asserts.ts'
-import yargs from '../../deno.ts'
-import { Arguments } from '../../deno-types.ts'
-import { commands } from '../esm/fixtures/commands/index.mjs'
+  assertMatch,
+} from 'https://deno.land/std/testing/asserts.ts';
+import yargs from '../../deno.ts';
+import {Arguments} from '../../deno-types.ts';
+import {commands} from '../esm/fixtures/commands/index.mjs';
 
 Deno.test('demandCommand(1) throw error if no command provided', () => {
-  let err: Error|null = null
+  let err: Error | null = null;
   yargs()
     .demandCommand(1)
     .parse(Deno.args, (_err: Error) => {
-      err = _err
-    })
-  assertMatch(err!.message, /Not enough non-option/)
-})
+      err = _err;
+    });
+  assertMatch(err!.message, /Not enough non-option/);
+});
 
 // TODO: we should think of a way to support this functionality
 Deno.test('guesses version # based on package.json', () => {
-  let output: string|null = null
-  yargs()
-    .parse('--version', (_err: Error, argv: Arguments, _output: string) => {
-      output = _output
-    })
-  assertMatch('' + output, /[0-9]+\.[0-9]+\.[0-9]+/)
-})
+  let output: string | null = null;
+  yargs().parse(
+    '--version',
+    (_err: Error, argv: Arguments, _output: string) => {
+      output = _output;
+    }
+  );
+  assertMatch('' + output, /[0-9]+\.[0-9]+\.[0-9]+/);
+});
 
 // Handling of strings that look like numbers, see:
 // https://github.com/yargs/yargs/issues/1758
-Deno.test('does not drop .0 if positional is configured as string', async () => {
-  const argv = await yargs(['cmd', '33.0'])
-    .command('cmd [str]', 'a command', (yargs: any) => {
-      return yargs.positional('str', {
-        type: 'string'
+Deno.test(
+  'does not drop .0 if positional is configured as string',
+  async () => {
+    const argv = (await yargs(['cmd', '33.0'])
+      .command('cmd [str]', 'a command', (yargs: any) => {
+        return yargs.positional('str', {
+          type: 'string',
+        });
       })
-    }).parse() as Arguments
-  assertEquals(argv.str, '33.0')
-})
+      .parse()) as Arguments;
+    assertEquals(argv.str, '33.0');
+  }
+);
 
 Deno.test('hierarchy of commands', async () => {
   const context = {
@@ -46,4 +52,4 @@ Deno.test('hierarchy of commands', async () => {
   };
   yargs().command(commands).parse('a c 10 5', context);
   assertEquals(context.output.value, 15);
-})
+});
diff --git a/test/esm/fixtures/commands/a.mjs b/test/esm/fixtures/commands/a.mjs
index 90fc41265..4f2a86fa4 100644
--- a/test/esm/fixtures/commands/a.mjs
+++ b/test/esm/fixtures/commands/a.mjs
@@ -5,4 +5,5 @@ export const describe = 'numeric commands';
 export const builder = yargs => {
   yargs.command(commands);
 };
+// eslint-disable-next-line no-unused-vars
 export const handler = function (argv) {};
diff --git a/test/esm/fixtures/commands/subcommands/c.mjs b/test/esm/fixtures/commands/subcommands/c.mjs
index 8085aeb95..3c6cc49da 100644
--- a/test/esm/fixtures/commands/subcommands/c.mjs
+++ b/test/esm/fixtures/commands/subcommands/c.mjs
@@ -1,5 +1,6 @@
 export const command = 'c <x> <y>';
 export const describe = 'add x to y';
+// eslint-disable-next-line no-unused-vars
 export const builder = yargs => {};
 export const handler = function (argv) {
   argv.output.value = argv.x + argv.y;
diff --git a/test/esm/fixtures/commands/subcommands/d.mjs b/test/esm/fixtures/commands/subcommands/d.mjs
index 62c937dfe..4f4d456c4 100644
--- a/test/esm/fixtures/commands/subcommands/d.mjs
+++ b/test/esm/fixtures/commands/subcommands/d.mjs
@@ -1,5 +1,6 @@
 export const command = 'd <x> <y>';
 export const describe = 'multiply x by y';
+// eslint-disable-next-line no-unused-vars
 export const builder = yargs => {};
 export const handler = function (argv) {
   argv.output.value = argv.x * argv.y;
diff --git a/test/fixtures/bin.js b/test/fixtures/bin.js
index 76889cb82..dfa0d62e0 100755
--- a/test/fixtures/bin.js
+++ b/test/fixtures/bin.js
@@ -1,6 +1,5 @@
 #!/usr/bin/env node
-var argv = require('../../')
-  .help('help')
-  .completion()
-  .argv
-console.log(JSON.stringify(argv._))
+/* eslint-disable node/shebang */
+// eslint-disable-next-line no-undef
+const argv = require('../../').help('help').completion().argv;
+console.log(JSON.stringify(argv._));
diff --git a/test/fixtures/cmddir/deep/deeper/deeper_still/limbo.js b/test/fixtures/cmddir/deep/deeper/deeper_still/limbo.js
index 9b8d0cc73..28ffad452 100644
--- a/test/fixtures/cmddir/deep/deeper/deeper_still/limbo.js
+++ b/test/fixtures/cmddir/deep/deeper/deeper_still/limbo.js
@@ -1,28 +1,35 @@
-exports.command = 'limbo [opts]'
-exports.desc = 'Get lost in pure subconscious'
+/* eslint-disable no-undef */
+exports.command = 'limbo [opts]';
+exports.desc = 'Get lost in pure subconscious';
 exports.builder = {
   'with-self-exit': {
     desc: 'Pretty much your only way out',
-    type: 'boolean'
+    type: 'boolean',
   },
   'with-totem': {
     desc: 'Take your totem with you',
-    type: 'boolean'
-  }
-}
+    type: 'boolean',
+  },
+};
 exports.handler = function (argv) {
-  var factor = 3
-  if (!argv.withSelfExit) throw new Error('You entered limbo without a way out!')
-  if (!argv.withTotem) factor -= 2
+  let factor = 3;
+  if (!argv.withSelfExit)
+    throw new Error('You entered limbo without a way out!');
+  if (!argv.withTotem) factor -= 2;
   if (argv.extract) {
-    if (!chancesLevel4(factor)) throw new Error('You didn\'t have much chance anyway, you\'re stuck in limbo!')
-    if (!argv._msg) argv._msg = 'You have accomplished the impossible. Inception successful.'
-    return
+    if (!chancesLevel4(factor))
+      throw new Error(
+        "You didn't have much chance anyway, you're stuck in limbo!"
+      );
+    if (!argv._msg)
+      argv._msg = 'You have accomplished the impossible. Inception successful.';
+    return;
   }
-  if (!chancesLevel4(factor)) throw new Error('You rolled the dice and lost, you\'re stuck in limbo!')
-  if (!argv._msg) argv._msg = 'Can you ever be sure of what\'s real anymore?'
-}
+  if (!chancesLevel4(factor))
+    throw new Error("You rolled the dice and lost, you're stuck in limbo!");
+  if (!argv._msg) argv._msg = "Can you ever be sure of what's real anymore?";
+};
 
-function chancesLevel4 (factor) {
-  return Math.floor(Math.random() * 10) < factor
+function chancesLevel4(factor) {
+  return Math.floor(Math.random() * 10) < factor;
 }
diff --git a/test/fixtures/cmddir/deep/deeper/inception.js b/test/fixtures/cmddir/deep/deeper/inception.js
index 4ee5e7423..6e4667b3e 100644
--- a/test/fixtures/cmddir/deep/deeper/inception.js
+++ b/test/fixtures/cmddir/deep/deeper/inception.js
@@ -1,32 +1,39 @@
-exports.command = 'inception [command] [opts]'
-exports.desc = 'Enter another dream, where inception is possible'
+/* eslint-disable no-undef */
+exports.command = 'inception [command] [opts]';
+exports.desc = 'Enter another dream, where inception is possible';
 exports.builder = function (yargs) {
   return yargs
     .commandDir('deeper_still')
     .option('with-sedation', {
       desc: 'Apply a sedative?',
       type: 'boolean',
-      global: true
+      global: true,
     })
     .option('with-timed-kick', {
       desc: 'Plan an elaborate timed kick at each layer?',
       type: 'boolean',
-      global: true
-    })
-}
+      global: true,
+    });
+};
 exports.handler = function (argv) {
-  var factor = 5
+  let factor = 5;
   if (argv.extract) {
-    if (!argv.withSedation) factor -= 1
-    if (!argv.withTimedKick) factor -= 1
-    if (!chancesLevel3(factor)) throw new Error('Something went wrong at level 3! Check your options for increased chance of success.')
-    if (!argv._msg) argv._msg = 'You have narrowly escaped disaster. Inception successful.'
-    return
+    if (!argv.withSedation) factor -= 1;
+    if (!argv.withTimedKick) factor -= 1;
+    if (!chancesLevel3(factor))
+      throw new Error(
+        'Something went wrong at level 3! Check your options for increased chance of success.'
+      );
+    if (!argv._msg)
+      argv._msg = 'You have narrowly escaped disaster. Inception successful.';
+    return;
   }
-  if (!chancesLevel3(factor)) throw new Error('You can no longer tell a dream from reality!')
-  if (!argv._msg) argv._msg = 'Be very careful, you\'re starting to lose grip on reality.'
-}
+  if (!chancesLevel3(factor))
+    throw new Error('You can no longer tell a dream from reality!');
+  if (!argv._msg)
+    argv._msg = "Be very careful, you're starting to lose grip on reality.";
+};
 
-function chancesLevel3 (factor) {
-  return Math.floor(Math.random() * 10) < factor
+function chancesLevel3(factor) {
+  return Math.floor(Math.random() * 10) < factor;
 }
diff --git a/test/fixtures/cmddir/deep/within-a-dream.js b/test/fixtures/cmddir/deep/within-a-dream.js
index b6d2f1942..7281d3c0a 100644
--- a/test/fixtures/cmddir/deep/within-a-dream.js
+++ b/test/fixtures/cmddir/deep/within-a-dream.js
@@ -1,28 +1,31 @@
+/* eslint-disable no-undef */
 module.exports = {
   command: 'within-a-dream [command] [opts]',
   desc: 'Dream within a dream',
   builder: function (yargs) {
-    return yargs
-      .commandDir('deeper')
-      .option('with-kick', {
-        desc: 'Plan a kick for controlled wake up?',
-        type: 'boolean',
-        global: true
-      })
+    return yargs.commandDir('deeper').option('with-kick', {
+      desc: 'Plan a kick for controlled wake up?',
+      type: 'boolean',
+      global: true,
+    });
   },
   handler: function (argv) {
-    var factor = 7
-    if (argv.context) argv.context.counter++ // keep track of how many times we've invoked this handler.
+    let factor = 7;
+    if (argv.context) argv.context.counter++; // keep track of how many times we've invoked this handler.
     if (argv.extract) {
-      if (!argv.withKick) factor -= 2
-      if (!chancesLevel2(factor)) throw new Error('Something went wrong at level 2! Check your options for increased chance of success.')
-      if (!argv._msg) argv._msg = 'You got lucky this time. Extraction successful.'
-      return
+      if (!argv.withKick) factor -= 2;
+      if (!chancesLevel2(factor))
+        throw new Error(
+          'Something went wrong at level 2! Check your options for increased chance of success.'
+        );
+      if (!argv._msg)
+        argv._msg = 'You got lucky this time. Extraction successful.';
+      return;
     }
-    if (!argv._msg) argv._msg = 'Let\'s not make a habit of this.'
-  }
-}
+    if (!argv._msg) argv._msg = "Let's not make a habit of this.";
+  },
+};
 
-function chancesLevel2 (factor) {
-  return Math.floor(Math.random() * 10) < factor
+function chancesLevel2(factor) {
+  return Math.floor(Math.random() * 10) < factor;
 }
diff --git a/test/fixtures/cmddir/dream.js b/test/fixtures/cmddir/dream.js
index d66cef6a4..1b058cc0b 100644
--- a/test/fixtures/cmddir/dream.js
+++ b/test/fixtures/cmddir/dream.js
@@ -1,31 +1,36 @@
-exports.command = 'dream [command] [opts]'
-exports.desc = 'Go to sleep and dream'
+/* eslint-disable no-undef */
+exports.command = 'dream [command] [opts]';
+exports.desc = 'Go to sleep and dream';
 exports.builder = function (yargs) {
   return yargs
     .commandDir('deep', {
-      extensions: ['js', 'json']
+      extensions: ['js', 'json'],
     })
     .option('shared', {
       desc: 'Is the dream shared with others?',
       type: 'boolean',
-      global: true
+      global: true,
     })
     .option('extract', {
       desc: 'Attempt extraction?',
       type: 'boolean',
-      global: true
-    })
-}
+      global: true,
+    });
+};
 exports.handler = function (argv) {
   if (argv.extract) {
-    if (!argv.shared) throw new Error('Dream is not shared, there is no one to extract from!')
-    if (!chancesLevel1()) throw new Error('Extraction failed!')
-    if (!argv._msg) argv._msg = 'Extraction succesful'
+    if (!argv.shared)
+      throw new Error('Dream is not shared, there is no one to extract from!');
+    if (!chancesLevel1()) throw new Error('Extraction failed!');
+    if (!argv._msg) argv._msg = 'Extraction succesful';
   }
-  if (argv._msg) console.log(argv._msg)
-  else console.log(argv.shared ? 'Training session over' : 'Well, that was a refreshing nap')
-}
+  if (argv._msg) console.log(argv._msg);
+  else
+    console.log(
+      argv.shared ? 'Training session over' : 'Well, that was a refreshing nap'
+    );
+};
 
-function chancesLevel1 () {
-  return Math.floor(Math.random() * 10) < 9
+function chancesLevel1() {
+  return Math.floor(Math.random() * 10) < 9;
 }
diff --git a/test/fixtures/cmddir_cyclic/cyclic.js b/test/fixtures/cmddir_cyclic/cyclic.js
index b506260c2..479fc499d 100644
--- a/test/fixtures/cmddir_cyclic/cyclic.js
+++ b/test/fixtures/cmddir_cyclic/cyclic.js
@@ -1,6 +1,7 @@
-exports.command = 'cyclic'
-exports.description = 'Attempts to (re)apply its own dir'
+/* eslint-disable no-undef */
+exports.command = 'cyclic';
+exports.description = 'Attempts to (re)apply its own dir';
 exports.builder = function (yargs) {
-  return yargs.commandDir('../cmddir_cyclic')
-}
-exports.handler = function (argv) {}
+  return yargs.commandDir('../cmddir_cyclic');
+};
+exports.handler = function () {};
diff --git a/test/fixtures/cmddir_noname/nameless.js b/test/fixtures/cmddir_noname/nameless.js
index 6da3ae9a2..b2ae2ca6d 100644
--- a/test/fixtures/cmddir_noname/nameless.js
+++ b/test/fixtures/cmddir_noname/nameless.js
@@ -1,14 +1,15 @@
-exports.description = 'Command name derived from module filename'
+/* eslint-disable no-undef */
+exports.description = 'Command name derived from module filename';
 
 exports.builder = {
   banana: {
-    default: 'cool'
+    default: 'cool',
   },
   batman: {
-    default: 'sad'
-  }
-}
+    default: 'sad',
+  },
+};
 
 exports.handler = function (argv) {
-  global.commandHandlerCalledWith = argv
-}
+  global.commandHandlerCalledWith = argv;
+};
diff --git a/test/fixtures/command-module.js b/test/fixtures/command-module.js
index b43c84cf3..d79a9dc9d 100644
--- a/test/fixtures/command-module.js
+++ b/test/fixtures/command-module.js
@@ -1,17 +1,18 @@
-exports.command = 'blerg <foo>'
+/* eslint-disable no-undef */
+exports.command = 'blerg <foo>';
 
-exports.describe = 'handle blerg things'
+exports.describe = 'handle blerg things';
 
 exports.builder = function (yargs) {
   return yargs
     .option('banana', {
-      default: 'cool'
+      default: 'cool',
     })
     .option('batman', {
-      default: 'sad'
-    })
-}
+      default: 'sad',
+    });
+};
 
 exports.handler = function (argv) {
-  global.commandHandlerCalledWith = argv
-}
+  global.commandHandlerCalledWith = argv;
+};
diff --git a/test/fixtures/command.js b/test/fixtures/command.js
index 92cf5255b..3aa83b7d4 100644
--- a/test/fixtures/command.js
+++ b/test/fixtures/command.js
@@ -1,12 +1,13 @@
+/* eslint-disable no-undef */
 exports.builder = {
   banana: {
-    default: 'cool'
+    default: 'cool',
   },
   batman: {
-    default: 'sad'
-  }
-}
+    default: 'sad',
+  },
+};
 
 exports.handler = function (argv) {
-  global.commandHandlerCalledWith = argv
-}
+  global.commandHandlerCalledWith = argv;
+};
diff --git a/test/fixtures/issue-497.js b/test/fixtures/issue-497.js
index fbec4e4de..cdf053f00 100755
--- a/test/fixtures/issue-497.js
+++ b/test/fixtures/issue-497.js
@@ -1,19 +1,22 @@
 #!/usr/bin/env node
+/* eslint-disable node/shebang */
 
+/* eslint-disable no-undef */
 // pretend we are a TTY
-process.stdout.isTTY = true
-process.stderr.isTTY = true
+process.stdout.isTTY = true;
+process.stderr.isTTY = true;
 
-var yargs = require('../../')
-var y = yargs.command('download <url> <files..>', 'make a get HTTP request')
-  .help()
+const yargs = require('../../');
+const y = yargs
+  .command('download <url> <files..>', 'make a get HTTP request')
+  .help();
 
-for (var i = 0; i < 1000; i++) {
+for (let i = 0; i < 1000; i++) {
   yargs.option('o' + i, {
-    describe: 'option ' + i
-  })
+    describe: 'option ' + i,
+  });
 }
 
-y.parse()
+y.parse();
 
-console.log('never get here')
+console.log('never get here');
diff --git a/test/fixtures/no-require-main.js b/test/fixtures/no-require-main.js
index 63b325735..ae5f902a0 100755
--- a/test/fixtures/no-require-main.js
+++ b/test/fixtures/no-require-main.js
@@ -1,13 +1,16 @@
 #!/usr/bin/env node
-
-'use strict'
+/* eslint-disable node/shebang */
+/* eslint-disable no-undef */
+'use strict';
 
 // for some unknown reason, a test environment has decided to omit require.main
-delete require.main
+delete require.main;
 
-var parser = require('../../')(process.argv.slice(2), undefined, require)
+const parser = require('../../')(process.argv.slice(2), undefined, require);
 
-console.log(parser.parserConfiguration({
-  'dot-notation': false,
-  'boolean-negation': false
-}).argv)
+console.log(
+  parser.parserConfiguration({
+    'dot-notation': false,
+    'boolean-negation': false,
+  }).argv
+);
diff --git a/test/fixtures/normal-bin.js b/test/fixtures/normal-bin.js
index 426e50e3c..5b71b1a5d 100755
--- a/test/fixtures/normal-bin.js
+++ b/test/fixtures/normal-bin.js
@@ -1,10 +1,8 @@
 #!/usr/bin/env node
-var argv = require('../../')
-  .help('help')
-  .version()
-  .parserConfiguration({
-    'dot-notation': false,
-    'boolean-negation': false
-  })
-  .argv
-console.log(argv)
+/* eslint-disable no-undef */
+/* eslint-disable node/shebang */
+const argv = require('../../').help('help').version().parserConfiguration({
+  'dot-notation': false,
+  'boolean-negation': false,
+}).argv;
+console.log(argv);
diff --git a/test/fixtures/opt-assignment-and-positional-command-arg.js b/test/fixtures/opt-assignment-and-positional-command-arg.js
index 7ded499df..9f78dc1b7 100755
--- a/test/fixtures/opt-assignment-and-positional-command-arg.js
+++ b/test/fixtures/opt-assignment-and-positional-command-arg.js
@@ -1,14 +1,18 @@
 #!/usr/bin/env node
+/* eslint-disable node/shebang */
+/* eslint-disable no-undef */
 require('../../')
   .option('foo', {
-    nargs: 1
+    nargs: 1,
   })
   .command(
     'bar <baz>',
     'example',
-    function (yargs) { return yargs },
-    function (argv) {
-      console.log(JSON.stringify({ _: argv._, foo: argv.foo, baz: argv.baz }))
+    yargs => {
+      return yargs;
+    },
+    argv => {
+      console.log(JSON.stringify({_: argv._, foo: argv.foo, baz: argv.baz}));
     }
   )
-  .parse()
+  .parse();
diff --git a/test/fixtures/symlink-bin.js b/test/fixtures/symlink-bin.js
index da53b4bba..2c97060bc 100755
--- a/test/fixtures/symlink-bin.js
+++ b/test/fixtures/symlink-bin.js
@@ -1,10 +1,11 @@
 #!/usr/bin/env node
-var argv = require('./yargs-symlink')
+/* eslint-disable node/shebang */
+/* eslint-disable no-undef */
+const argv = require('./yargs-symlink')
   .help('help')
   .version()
   .parserConfiguration({
     'dot-notation': false,
-    'boolean-negation': false
-  })
-  .argv
-console.log(argv)
+    'boolean-negation': false,
+  }).argv;
+console.log(argv);
diff --git a/test/middleware.cjs b/test/middleware.cjs
index 4efe10300..ed1074c81 100644
--- a/test/middleware.cjs
+++ b/test/middleware.cjs
@@ -1,5 +1,6 @@
 'use strict';
 /* global describe, it, beforeEach, afterEach */
+/* eslint-disable no-unused-vars */
 
 const {expect} = require('chai');
 const {globalMiddlewareFactory} = require('../build/index.cjs');
@@ -524,9 +525,9 @@ describe('middleware', () => {
                 argv.bar = 'hello';
                 return resolve();
               }, 100);
-            })
+            });
           }, true)
-          .check((argv) => {
+          .check(argv => {
             if (argv.foo > 100) return true;
             else return false;
           })
@@ -538,11 +539,7 @@ describe('middleware', () => {
 
       it('applies middleware before performing validation, with explicit $0', async () => {
         const argvEventual = yargs('--foo 100')
-          .usage(
-            '$0',
-            'usage',
-            () => {},
-          )
+          .usage('$0', 'usage', () => {})
           .option('bar', {
             demand: true,
           })
@@ -553,9 +550,9 @@ describe('middleware', () => {
                 argv.bar = 'hello';
                 return resolve();
               }, 100);
-            })
+            });
           }, true)
-          .check((argv) => {
+          .check(argv => {
             if (argv.foo > 100) return true;
             else return false;
           })
@@ -599,12 +596,11 @@ describe('middleware', () => {
         })
         .middleware(argv => {
           argv.foo = argv.foo * 2;
-          argv.bar = 'hello'
+          argv.bar = 'hello';
         }, true)
-        .check((argv) => {
+        .check(argv => {
           if (argv.foo > 100) return true;
           else return false;
-          return true;
         })
         .parse();
       argv.foo.should.equal(200);
@@ -615,11 +611,16 @@ describe('middleware', () => {
   // Refs: https://github.com/yargs/yargs/issues/1351
   it('should run even if no command is matched', () => {
     const argv = yargs('snuh --foo 99')
-    .middleware(argv => {
-      argv.foo = argv.foo * 2;
-    })
-    .command('bar', 'bar command', () => {}, () => {})
-    .parse();
+      .middleware(argv => {
+        argv.foo = argv.foo * 2;
+      })
+      .command(
+        'bar',
+        'bar command',
+        () => {},
+        () => {}
+      )
+      .parse();
     argv.foo.should.equal(198);
   });
 });
diff --git a/test/usage.cjs b/test/usage.cjs
index a2ae6a688..355455bbb 100644
--- a/test/usage.cjs
+++ b/test/usage.cjs
@@ -1,5 +1,6 @@
 'use strict';
 /* global describe, it, beforeEach */
+/* eslint-disable no-unused-vars */
 
 const checkUsage = require('./helpers/utils.cjs').checkOutput;
 const chalk = require('chalk');
diff --git a/test/validation.cjs b/test/validation.cjs
index eaf9ab4e5..3db8d2835 100644
--- a/test/validation.cjs
+++ b/test/validation.cjs
@@ -1,5 +1,6 @@
 'use strict';
 /* global describe, it, beforeEach */
+/* eslint-disable no-unused-vars */
 
 const checkUsage = require('./helpers/utils.cjs').checkOutput;
 const expect = require('chai').expect;
diff --git a/test/yargs.cjs b/test/yargs.cjs
index bec35d5c3..e279ec425 100644
--- a/test/yargs.cjs
+++ b/test/yargs.cjs
@@ -1,5 +1,6 @@
 'use strict';
 /* global context, describe, it, beforeEach, afterEach */
+/* eslint-disable no-unused-vars */
 
 const expect = require('chai').expect;
 const fs = require('fs');
@@ -3067,15 +3068,11 @@ describe('yargs dsl tests', () => {
     });
     // Refs: #1853
     it('should use cached help message for nested synchronous commands', async () => {
-      const y = yargs('object').command(
-        'object',
-        'object command',
-        (yargs) => {
-          yargs.command('get', 'get command');
-        }
-      );
+      const y = yargs('object').command('object', 'object command', yargs => {
+        yargs.command('get', 'get command');
+      });
       const argv = y.argv;
-      const help = (await y.getHelp());
+      const help = await y.getHelp();
       help.should.match(/node object get/);
       argv._.should.eql(['object']);
     });