feat: add new rule no-only-tests

Author: bmish

README.md

@@ -53,6 +53,7 @@ Name | ✔️ | 🛠 | Description
 [no-deprecated-report-api](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-deprecated-report-api.md) | ✔️ | 🛠 | disallow use of the deprecated context.report() API
 [no-identical-tests](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-identical-tests.md) | ✔️ | 🛠 | disallow identical tests
 [no-missing-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-missing-placeholders.md) | ✔️ |  | disallow missing placeholders in rule report messages
+[no-only-tests](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-only-tests.md) |  |  | disallow the test case property `only`
 [no-unused-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-unused-placeholders.md) | ✔️ |  | disallow unused placeholders in rule report messages
 [no-useless-token-range](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-useless-token-range.md) | ✔️ | 🛠 | disallow unnecessary calls to sourceCode.getFirstToken and sourceCode.getLastToken
 [prefer-object-rule](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/prefer-object-rule.md) |  | 🛠 | disallow rule exports where the export is a function.

docs/rules/no-only-tests.md

@@ -0,0 +1,49 @@
+# Disallow the test case property `only` (no-only-tests)
+
+The [`only` property](https://eslint.org/docs/developer-guide/unit-tests#running-individual-tests) can be used as of [ESLint 7.29](https://eslint.org/blog/2021/06/eslint-v7.29.0-released#highlights) for running individual rule test cases with less-noisy debugging. This feature should be only used in development, as it prevents all the tests from running. Mistakenly checking-in a test case with this property can cause CI tests to incorrectly pass.
+
+## Rule Details
+
+This rule flags a violation when a test case is using `only`. Note that this rule is not autofixable since automatically deleting the property would prevent developers from being able to use it during development.
+
+Examples of **incorrect** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-only-tests: error */
+
+ruleTester.run('my-rule', myRule, {
+  valid: [
+    {
+      code: 'const valid = 42;',
+      only: true,
+    },
+    RuleTester.only('const valid = 42;'),
+  ],
+  invalid: [
+    {
+      code: 'const invalid = 42;',
+      only: true,
+      errors: [/* ... */],
+    },
+  ],
+});
+```
+
+Examples of **correct** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-only-tests: error */
+
+ruleTester.run('my-rule', myRule, {
+  valid: [
+    'const valid = 42;',
+    { code: 'const valid = 42;' }
+  ],
+  invalid: [
+    {
+      code: 'const invalid = 42;',
+      errors: [/* ... */],
+    },
+  ],
+});
+```

lib/rules/no-only-tests.js

@@ -0,0 +1,55 @@
+'use strict';
+
+const utils = require('../utils');
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow the test case property `only`',
+      category: 'Tests',
+      recommended: false,
+    },
+    schema: [],
+    messages: {
+      foundOnly:
+        'The test case property `only` can be used during development, but should not be checked-in, since it prevents all the tests from running.',
+    },
+  },
+
+  create (context) {
+    return {
+      Program (ast) {
+        for (const testRun of utils.getTestInfo(context, ast)) {
+          for (const test of [...testRun.valid, ...testRun.invalid]) {
+            if (test.type === 'ObjectExpression') {
+              // Test case object: { code: 'const x = 123;', ... }
+
+              const onlyProperty = test.properties.find(
+                property =>
+                  property.key.type === 'Identifier' &&
+                  property.key.name === 'only' &&
+                  property.value.type === 'Literal' &&
+                  property.value.value
+              );
+
+              if (onlyProperty) {
+                context.report({ node: onlyProperty, messageId: 'foundOnly' });
+              }
+            } else if (
+              test.type === 'CallExpression' &&
+              test.callee.type === 'MemberExpression' &&
+              test.callee.object.type === 'Identifier' &&
+              test.callee.object.name === 'RuleTester' &&
+              test.callee.property.type === 'Identifier' &&
+              test.callee.property.name === 'only'
+            ) {
+              // RuleTester.only('const x = 123;');
+              context.report({ node: test.callee, messageId: 'foundOnly' });
+            }
+          }
+        }
+      },
+    };
+  },
+};

tests/lib/rules/no-only-tests.js

@@ -0,0 +1,85 @@
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const rule = require('../../../lib/rules/no-only-tests');
+const RuleTester = require('eslint').RuleTester;
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester();
+ruleTester.run('no-only-tests', rule, {
+  valid: [
+    // No test cases with `only`
+    `
+      new RuleTester().run('foo', bar, {
+        valid: [
+          'foo',
+          { code: 'foo', foo: true },
+          RuleTester.somethingElse(),
+          notRuleTester.only()
+        ],
+        invalid: [
+          { code: 'bar', foo: true },
+        ]
+      });
+    `,
+    // `only` set to `false`
+    `
+      new RuleTester().run('foo', bar, {
+        valid: [
+          { code: 'foo', only: false },
+        ],
+        invalid: [
+          { code: 'bar', only: false },
+        ]
+      });
+    `,
+  ],
+
+  invalid: [
+    {
+      // Valid test case with `only`
+      code: `
+        new RuleTester().run('foo', bar, {
+          valid: [
+            { code: 'foo', only: true },
+          ],
+          invalid: []
+        });
+      `,
+      output: null,
+      errors: [{ messageId: 'foundOnly', type: 'Property', line: 4, endLine: 4, column: 28, endColumn: 38 }],
+    },
+    {
+      // Valid test case using `RuleTester.only`
+      code: `
+        new RuleTester().run('foo', bar, {
+          valid: [
+            RuleTester.only('foo'),
+          ],
+          invalid: []
+        });
+      `,
+      output: null,
+      errors: [{ messageId: 'foundOnly', type: 'MemberExpression', line: 4, endLine: 4, column: 13, endColumn: 28 }],
+    },
+    {
+      // Invalid test case with `only`
+      code: `
+        new RuleTester().run('foo', bar, {
+          valid: [],
+          invalid: [
+            { code: 'foo', only: true },
+          ]
+        });
+      `,
+      output: null,
+      errors: [{ messageId: 'foundOnly', type: 'Property', line: 5, endLine: 5, column: 28, endColumn: 38 }],
+    },
+  ],
+});