test: add tests for eslint rules

This adds tests for the custom eslint rules in this repository, using
the `RuleTester` test utility bundled with eslint.

PR-URL: https://github.com/nodejs/node/pull/16138
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-eslint-alphabetize-errors.js

@@ -0,0 +1,26 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/alphabetize-errors');
+
+new RuleTester().run('alphabetize-errors', rule, {
+  valid: [
+    `
+      E('AAA', 'foo');
+      E('BBB', 'bar');
+      E('CCC', 'baz');
+    `
+  ],
+  invalid: [
+    {
+      code: `
+        E('BBB', 'bar');
+        E('AAA', 'foo');
+        E('CCC', 'baz');
+      `,
+      errors: [{ message: 'Out of ASCIIbetical order - BBB >= AAA', line: 3 }]
+    }
+  ]
+});

test/parallel/test-eslint-buffer-constructor.js

@@ -0,0 +1,26 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/buffer-constructor');
+
+const message = 'Use of the Buffer() constructor has been deprecated. ' +
+                'Please use either Buffer.alloc(), Buffer.allocUnsafe(), ' +
+                'or Buffer.from()';
+
+new RuleTester().run('buffer-constructor', rule, {
+  valid: [
+    'Buffer.from(foo)'
+  ],
+  invalid: [
+    {
+      code: 'Buffer(foo)',
+      errors: [{ message }]
+    },
+    {
+      code: 'new Buffer(foo)',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-crypto-check.js

@@ -0,0 +1,32 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/crypto-check');
+
+const message = 'Please add a hasCrypto check to allow this test to be ' +
+                'skipped when Node is built "--without-ssl".';
+
+new RuleTester().run('crypto-check', rule, {
+  valid: [
+    'foo',
+    'crypto',
+    `
+      if (!common.hasCrypto) {
+        common.skip();
+      }
+      require('crypto');
+    `
+  ],
+  invalid: [
+    {
+      code: 'require("crypto")',
+      errors: [{ message }]
+    },
+    {
+      code: 'if (common.foo) {} require("crypto")',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-inspector-check.js

@@ -0,0 +1,23 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/inspector-check');
+
+const message = 'Please add a skipIfInspectorDisabled() call to allow this ' +
+                'test to be skippped when Node is built ' +
+                '\'--without-inspector\'.';
+
+new RuleTester().run('inspector-check', rule, {
+  valid: [
+    'foo;',
+    'common.skipIfInspectorDisabled(); require("inspector");'
+  ],
+  invalid: [
+    {
+      code: 'require("inspector")',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-no-let-in-for-declaration.js

@@ -0,0 +1,38 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/no-let-in-for-declaration');
+
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+
+const message = 'Use of `let` as the loop variable in a for-loop is ' +
+                'not recommended. Please use `var` instead.';
+
+ruleTester.run('no-let-in-for-declaration', rule, {
+  valid: [
+    'let foo;',
+    'for (var foo = 1;;);',
+    'for (foo = 1;;);',
+    'for (;;);',
+    'for (const foo of bar);',
+    'for (var foo of bar);',
+    'for (const foo in bar);',
+    'for (var foo in bar);'
+  ],
+  invalid: [
+    {
+      code: 'for (let foo = 1;;);',
+      errors: [{ message }]
+    },
+    {
+      code: 'for (let foo in bar);',
+      errors: [{ message }]
+    },
+    {
+      code: 'for (let foo of bar);',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-no-unescaped-regexp-dot.js

@@ -0,0 +1,28 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/no-unescaped-regexp-dot');
+
+new RuleTester().run('no-unescaped-regexp-dot', rule, {
+  valid: [
+    '/foo/',
+    String.raw`/foo\./`,
+    '/.+/',
+    '/.*/',
+    '/.?/',
+    '/.{5}/',
+    String.raw`/\\\./`
+  ],
+  invalid: [
+    {
+      code: '/./',
+      errors: [{ message: 'Unescaped dot character in regular expression' }]
+    },
+    {
+      code: String.raw`/\\./`,
+      errors: [{ message: 'Unescaped dot character in regular expression' }]
+    }
+  ]
+});

test/parallel/test-eslint-prefer-assert-iferror.js

@@ -0,0 +1,25 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/prefer-assert-iferror');
+
+new RuleTester().run('prefer-assert-iferror', rule, {
+  valid: [
+    'assert.ifError(err);',
+    'if (err) throw somethingElse;',
+    'throw err;',
+    'if (err) { throw somethingElse; }'
+  ],
+  invalid: [
+    {
+      code: 'if (err) throw err;',
+      errors: [{ message: 'Use assert.ifError(err) instead.' }]
+    },
+    {
+      code: 'if (error) { throw error; }',
+      errors: [{ message: 'Use assert.ifError(error) instead.' }]
+    }
+  ]
+});

test/parallel/test-eslint-prefer-assert-methods.js

@@ -0,0 +1,37 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/prefer-assert-methods');
+
+new RuleTester().run('prefer-assert-methods', rule, {
+  valid: [
+    'assert.strictEqual(foo, bar)',
+    'assert(foo === bar && baz)'
+  ],
+  invalid: [
+    {
+      code: 'assert(foo == bar)',
+      errors: [{ message: "'assert.equal' should be used instead of '=='" }]
+    },
+    {
+      code: 'assert(foo === bar)',
+      errors: [{
+        message: "'assert.strictEqual' should be used instead of '==='"
+      }]
+    },
+    {
+      code: 'assert(foo != bar)',
+      errors: [{
+        message: "'assert.notEqual' should be used instead of '!='"
+      }]
+    },
+    {
+      code: 'assert(foo !== bar)',
+      errors: [{
+        message: "'assert.notStrictEqual' should be used instead of '!=='"
+      }]
+    },
+  ]
+});

test/parallel/test-eslint-prefer-common-mustnotcall.js

@@ -0,0 +1,27 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/prefer-common-mustnotcall');
+
+const message = 'Please use common.mustNotCall(msg) instead of ' +
+                'common.mustCall(fn, 0) or common.mustCall(0).';
+
+new RuleTester().run('prefer-common-mustnotcall', rule, {
+  valid: [
+    'common.mustNotCall(fn)',
+    'common.mustCall(fn)',
+    'common.mustCall(fn, 1)'
+  ],
+  invalid: [
+    {
+      code: 'common.mustCall(fn, 0)',
+      errors: [{ message }]
+    },
+    {
+      code: 'common.mustCall(0)',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-require-buffer.js

@@ -0,0 +1,26 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/require-buffer');
+const ruleTester = new RuleTester({
+  parserOptions: { ecmaVersion: 6 },
+  env: { node: true }
+});
+
+const message = "Use const Buffer = require('buffer').Buffer; " +
+                'at the beginning of this file';
+
+ruleTester.run('require-buffer', rule, {
+  valid: [
+    'foo',
+    'const Buffer = require("Buffer"); Buffer;'
+  ],
+  invalid: [
+    {
+      code: 'Buffer;',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-eslint-required-modules.js

@@ -0,0 +1,31 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/required-modules');
+
+new RuleTester().run('required-modules', rule, {
+  valid: [
+    {
+      code: 'require("common")',
+      options: ['common']
+    },
+    {
+      code: 'foo',
+      options: []
+    },
+  ],
+  invalid: [
+    {
+      code: 'foo',
+      options: ['common'],
+      errors: [{ message: 'Mandatory module "common" must be loaded.' }]
+    },
+    {
+      code: 'require("somethingElse")',
+      options: ['common'],
+      errors: [{ message: 'Mandatory module "common" must be loaded.' }]
+    }
+  ]
+});