feat: create new prefer-ending-with-an-expect rule

Author: G-Rath

README.md

@@ -363,6 +363,7 @@ Manually fixable by
 | [prefer-called-with](docs/rules/prefer-called-with.md)                               | Suggest using `toBeCalledWith()` or `toHaveBeenCalledWith()`              |     |     |     |     |
 | [prefer-comparison-matcher](docs/rules/prefer-comparison-matcher.md)                 | Suggest using the built-in comparison matchers                            |     |     | 🔧  |     |
 | [prefer-each](docs/rules/prefer-each.md)                                             | Prefer using `.each` rather than manual loops                             |     |     |     |     |
+| [prefer-ending-with-an-expect](docs/rules/prefer-ending-with-an-expect.md)           | Prefer having the last statement in a test be an assertion                |     |     |     |     |
 | [prefer-equality-matcher](docs/rules/prefer-equality-matcher.md)                     | Suggest using the built-in equality matchers                              |     |     |     | 💡  |
 | [prefer-expect-assertions](docs/rules/prefer-expect-assertions.md)                   | Suggest using `expect.assertions()` OR `expect.hasAssertions()`           |     |     |     | 💡  |
 | [prefer-expect-resolves](docs/rules/prefer-expect-resolves.md)                       | Prefer `await expect(...).resolves` over `expect(await ...)` syntax       |     |     | 🔧  |     |

docs/rules/prefer-ending-with-an-expect.md

@@ -0,0 +1,168 @@
+# Prefer having the last statement in a test be an assertion (`prefer-ending-with-an-expect`)
+
+<!-- end auto-generated rule header -->
+
+Prefer ending tests with an `expect` assertion.
+
+## Rule details
+
+This rule triggers when a test body does not end with an `expect` call, which
+can indicate an unfinished test.
+
+Examples of **incorrect** code for this rule:
+
+```js
+it('lets me change the selected option', () => {
+  const container = render(MySelect, {
+    props: { options: [1, 2, 3], selected: 1 },
+  });
+
+  expect(container).toBeDefined();
+  expect(container.toHTML()).toContain('<option value="1" selected>');
+
+  container.setProp('selected', 2);
+});
+```
+
+Examples of **correct** code for this rule:
+
+```js
+it('lets me change the selected option', () => {
+  const container = render(MySelect, {
+    props: { options: [1, 2, 3], selected: 1 },
+  });
+
+  expect(container).toBeDefined();
+  expect(container.toHTML()).toContain('<option value="1" selected>');
+
+  container.setProp('selected', 2);
+
+  expect(container.toHTML()).not.toContain('<option value="1" selected>');
+  expect(container.toHTML()).toContain('<option value="2" selected>');
+});
+```
+
+## Options
+
+```json
+{
+  "jest/prefer-ending-with-an-expect": [
+    "error",
+    {
+      "assertFunctionNames": ["expect"],
+      "additionalTestBlockFunctions": []
+    }
+  ]
+}
+```
+
+### `assertFunctionNames`
+
+This array option specifies the names of functions that should be considered to
+be asserting functions. Function names can use wildcards i.e `request.*.expect`,
+`request.**.expect`, `request.*.expect*`
+
+Examples of **incorrect** code for the `{ "assertFunctionNames": ["expect"] }`
+option:
+
+```js
+/* eslint jest/prefer-ending-with-an-expect: ["error", { "assertFunctionNames": ["expect"] }] */
+
+import { expectSaga } from 'redux-saga-test-plan';
+import { addSaga } from '../src/sagas';
+
+test('returns sum', () => {
+  expectSaga(addSaga, 1, 1).returns(2).run();
+});
+```
+
+Examples of **correct** code for the
+`{ "assertFunctionNames": ["expect", "expectSaga"] }` option:
+
+```js
+/* eslint jest/prefer-ending-with-an-expect: ["error", { "assertFunctionNames": ["expect", "expectSaga"] }] */
+
+import { expectSaga } from 'redux-saga-test-plan';
+import { addSaga } from '../src/sagas';
+
+test('returns sum', () => {
+  expectSaga(addSaga, 1, 1).returns(2).run();
+});
+```
+
+Since the string is compiled into a regular expression, you'll need to escape
+special characters such as `$` with a double backslash:
+
+```js
+/* eslint jest/prefer-ending-with-an-expect: ["error", { "assertFunctionNames": ["expect\\$"] }] */
+
+it('is money-like', () => {
+  expect$(1.0);
+});
+```
+
+Examples of **correct** code for working with the HTTP assertions library
+[SuperTest](https://www.npmjs.com/package/supertest) with the
+`{ "assertFunctionNames": ["expect", "request.**.expect"] }` option:
+
+```js
+/* eslint jest/prefer-ending-with-an-expect: ["error", { "assertFunctionNames": ["expect", "request.**.expect"] }] */
+const request = require('supertest');
+const express = require('express');
+
+const app = express();
+
+describe('GET /user', function () {
+  it('responds with json', function (done) {
+    doSomething();
+
+    request(app).get('/user').expect('Content-Type', /json/).expect(200, done);
+  });
+});
+```
+
+### `additionalTestBlockFunctions`
+
+This array can be used to specify the names of functions that should also be
+treated as test blocks:
+
+```json
+{
+  "rules": {
+    "jest/prefer-ending-with-an-expect": [
+      "error",
+      { "additionalTestBlockFunctions": ["each.test"] }
+    ]
+  }
+}
+```
+
+The following is _correct_ when using the above configuration:
+
+```js
+each([
+  [2, 3],
+  [1, 3],
+]).test(
+  'the selection can change from %d to %d',
+  (firstSelection, secondSelection) => {
+    const container = render(MySelect, {
+      props: { options: [1, 2, 3], selected: firstSelection },
+    });
+
+    expect(container).toBeDefined();
+    expect(container.toHTML()).toContain(
+      `<option value="${firstSelection}" selected>`,
+    );
+
+    container.setProp('selected', secondSelection);
+
+    expect(container.toHTML()).not.toContain(
+      `<option value="${firstSelection}" selected>`,
+    );
+    expect(container.toHTML()).toContain(
+      `<option value="${secondSelection}" selected>`,
+    );
+  },
+);
+```