Add prefer-strict-equal matcher (#105)

* Add prefer-strict-equal matcher

* Update to `parseExpectCall`

* Rename

README.md

@@ -63,6 +63,7 @@ command line option.\
 |  ✔  |     | 💡  | [no-skipped-test](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/no-skipped-test.md)                       | Disallow usage of the `.skip` annotation                          |
 |  ✔  | 🔧  |     | [no-useless-not](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/no-useless-not.md)                         | Disallow usage of `not` matchers when a specific matcher exists   |
 |  ✔  |     | 💡  | [no-wait-for-timeout](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/no-wait-for-timeout.md)               | Disallow usage of `page.waitForTimeout`                           |
+|     |     | 💡  | [prefer-strict-equal](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/prefer-strict-equal.md)               | Suggest using `toStrictEqual()`                                   |
 |     | 🔧  |     | [prefer-lowercase-title](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/prefer-lowercase-title.md)         | Enforce lowercase test names                                      |
 |     | 🔧  |     | [prefer-to-be](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/prefer-to-be.md)                             | Suggest using `toBe()`                                            |
 |     | 🔧  |     | [prefer-to-have-length](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/prefer-to-have-length.md)           | Suggest using `toHaveLength()`                                    |

docs/rules/prefer-strict-equal.md

@@ -0,0 +1,24 @@
+# Suggest using `toStrictEqual()` (`prefer-strict-equal`)
+
+`toStrictEqual` not only checks that two objects contain the same data but also
+that they have the same structure. It is common to expect objects to not only
+have identical values but also to have identical keys. A stricter equality will
+catch cases where two objects do not have identical keys.
+
+## Rule details
+
+This rule triggers a warning if `toEqual()` is used to assert equality.
+
+### Default configuration
+
+The following pattern is considered warning:
+
+```javascript
+expect({ a: 'a', b: undefined }).toEqual({ a: 'a' }); // true
+```
+
+The following pattern is not warning:
+
+```javascript
+expect({ a: 'a', b: undefined }).toStrictEqual({ a: 'a' }); // false
+```

src/index.ts

@@ -13,6 +13,7 @@ import noUselessNot from './rules/no-useless-not';
 import preferLowercaseTitle from './rules/prefer-lowercase-title';
 import preferToBe from './rules/prefer-to-be';
 import preferToHaveLength from './rules/prefer-to-have-length';
+import preferStrictEqual from './rules/prefer-strict-equal';
 import requireTopLevelDescribe from './rules/require-top-level-describe';
 import validExpect from './rules/valid-expect';
 
@@ -86,6 +87,7 @@ export = {
     'no-useless-not': noUselessNot,
     'no-restricted-matchers': noRestrictedMatchers,
     'prefer-lowercase-title': preferLowercaseTitle,
+    'prefer-strict-equal': preferStrictEqual,
     'prefer-to-be': preferToBe,
     'prefer-to-have-length': preferToHaveLength,
     'require-top-level-describe': requireTopLevelDescribe,

src/rules/prefer-strict-equal.ts

@@ -0,0 +1,48 @@
+import { Rule } from 'eslint';
+import { replaceAccessorFixer } from '../utils/fixer';
+import { parseExpectCall } from '../utils/parseExpectCall';
+
+export default {
+  create(context) {
+    return {
+      CallExpression(node) {
+        const expectCall = parseExpectCall(node);
+
+        if (expectCall?.matcherName === 'toEqual') {
+          context.report({
+            node: expectCall.matcher,
+            messageId: 'useToStrictEqual',
+            suggest: [
+              {
+                messageId: 'suggestReplaceWithStrictEqual',
+                fix: (fixer) => {
+                  return replaceAccessorFixer(
+                    fixer,
+                    expectCall.matcher,
+                    'toStrictEqual'
+                  );
+                },
+              },
+            ],
+          });
+        }
+      },
+    };
+  },
+  meta: {
+    docs: {
+      category: 'Best Practices',
+      description: 'Suggest using `toStrictEqual()`',
+      recommended: false,
+      url: 'https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/prefer-strict-equal.md',
+    },
+    messages: {
+      useToStrictEqual: 'Use toStrictEqual() instead',
+      suggestReplaceWithStrictEqual: 'Replace with `toStrictEqual()`',
+    },
+    fixable: 'code',
+    type: 'suggestion',
+    hasSuggestions: true,
+    schema: [],
+  },
+} as Rule.RuleModule;

test/spec/prefer-strict-equal.spec.ts

@@ -0,0 +1,44 @@
+import { runRuleTester } from '../utils/rule-tester';
+import rule from '../../src/rules/prefer-strict-equal';
+
+runRuleTester('prefer-strict-equal', rule, {
+  valid: [
+    'expect(something).toStrictEqual(somethingElse);',
+    "a().toEqual('b')",
+    'expect(a);',
+  ],
+  invalid: [
+    {
+      code: 'expect(something).toEqual(somethingElse);',
+      errors: [
+        {
+          messageId: 'useToStrictEqual',
+          column: 19,
+          line: 1,
+          suggestions: [
+            {
+              messageId: 'suggestReplaceWithStrictEqual',
+              output: 'expect(something).toStrictEqual(somethingElse);',
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: 'expect(something)["toEqual"](somethingElse);',
+      errors: [
+        {
+          messageId: 'useToStrictEqual',
+          column: 19,
+          line: 1,
+          suggestions: [
+            {
+              messageId: 'suggestReplaceWithStrictEqual',
+              output: 'expect(something)["toStrictEqual"](somethingElse);',
+            },
+          ],
+        },
+      ],
+    },
+  ],
+});