chore: add prefer-to-contain rule

README.md

@@ -97,6 +97,7 @@ for more information about extending configuration files.
 | [prefer-strict-equal][]      | Suggest using `toStrictEqual()`                                   |                  | ![fixable-green][]  |
 | [prefer-to-be-null][]        | Suggest using `toBeNull()`                                        |                  | ![fixable-green][]  |
 | [prefer-to-be-undefined][]   | Suggest using `toBeUndefined()`                                   |                  | ![fixable-green][]  |
+| [prefer-to-contain][]        | Suggest using `toContain()`                                       |                  | ![fixable-green][]  |
 | [prefer-to-have-length][]    | Suggest using `toHaveLength()`                                    | ![recommended][] | ![fixable-green][]  |
 | [prefer-inline-snapshots][]  | Suggest using `toMatchInlineSnapshot()`                           |                  | ![fixable-green][]  |
 | [require-tothrow-message][]  | Require that `toThrow()` and `toThrowError` includes a message    |                  |                     |
@@ -126,6 +127,7 @@ for more information about extending configuration files.
 [prefer-strict-equal]: docs/rules/prefer-strict-equal.md
 [prefer-to-be-null]: docs/rules/prefer-to-be-null.md
 [prefer-to-be-undefined]: docs/rules/prefer-to-be-undefined.md
+[prefer-to-contain]: docs/rules/prefer-to-contain.md
 [prefer-to-have-length]: docs/rules/prefer-to-have-length.md
 [prefer-inline-snapshots]: docs/rules/prefer-inline-snapshots.md
 [require-tothrow-message]: docs/rules/require-tothrow-message.md

docs/rules/prefer-to-contain.md

@@ -0,0 +1,39 @@
+# Suggest using `toContain()` (prefer-to-contain)
+
+In order to have a better failure message, `toContain()` should be used upon
+asserting expectations on an array containing an object.
+
+## Rule details
+
+This rule triggers a warning if `toBe()` or `isEqual()` is used to assert object
+inclusion in an array
+
+```js
+expect(a.includes(b)).toBe(true);
+```
+
+```js
+expect(a.includes(b)).toBe(false);
+```
+
+### Default configuration
+
+The following patterns are considered a warning:
+
+```js
+expect(a.includes(b)).toBe(true);
+```
+
+```js
+expect(a.includes(b)).toBe(false);
+```
+
+The following patterns are not a warning:
+
+```js
+expect(a).toContain(b);
+```
+
+```js
+expect(a).toContain(b);
+```

index.js

@@ -14,6 +14,7 @@ const noTestPrefixes = require('./rules/no-test-prefixes');
 const noTestReturnStatement = require('./rules/no-test-return-statement');
 const preferToBeNull = require('./rules/prefer-to-be-null');
 const preferToBeUndefined = require('./rules/prefer-to-be-undefined');
+const preferToContain = require('./rules/prefer-to-contain');
 const preferToHaveLength = require('./rules/prefer-to-have-length');
 const validDescribe = require('./rules/valid-describe');
 const validExpect = require('./rules/valid-expect');
@@ -84,6 +85,7 @@ module.exports = {
     'no-test-return-statement': noTestReturnStatement,
     'prefer-to-be-null': preferToBeNull,
     'prefer-to-be-undefined': preferToBeUndefined,
+    'prefer-to-contain': preferToContain,
     'prefer-to-have-length': preferToHaveLength,
     'valid-describe': validDescribe,
     'valid-expect': validExpect,