From 420ee4c9d3fae67370a2d277fa860d245d72dfda Mon Sep 17 00:00:00 2001
From: Mark Skelton <mdskelton99@gmail.com>
Date: Mon, 19 Jun 2023 13:24:12 -0500
Subject: [PATCH] feat: Add `expect-expect` rule

---
 README.md                       |  1 +
 docs/rules/expect-expect.md     | 29 ++++++++++++++++++++
 src/index.ts                    |  3 +++
 src/rules/expect-expect.ts      | 48 +++++++++++++++++++++++++++++++++
 test/spec/expect-expect.spec.ts | 21 +++++++++++++++
 5 files changed, 102 insertions(+)
 create mode 100644 docs/rules/expect-expect.md
 create mode 100644 src/rules/expect-expect.ts
 create mode 100644 test/spec/expect-expect.spec.ts

diff --git a/README.md b/README.md
index 9a0e65e3..feb32c5b 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,7 @@ command line option.\
 
 |  ✔  | 🔧  | 💡  | Rule                                                                                                                                                | Description                                                       |
 | :-: | :-: | :-: | --------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
+|  ✔  |     |     | [expect-expect](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/expect-expect.md)                             | Enforce assertion to be made in a test body                       |
 |  ✔  |     |     | [max-nested-describe](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/max-nested-describe.md)                 | Enforces a maximum depth to nested describe calls                 |
 |  ✔  | 🔧  |     | [missing-playwright-await](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/missing-playwright-await.md)       | Enforce Playwright APIs to be awaited                             |
 |  ✔  |     |     | [no-conditional-in-test](https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/no-conditional-in-test.md)           | Disallow conditional logic in tests                               |
diff --git a/docs/rules/expect-expect.md b/docs/rules/expect-expect.md
new file mode 100644
index 00000000..9536baf2
--- /dev/null
+++ b/docs/rules/expect-expect.md
@@ -0,0 +1,29 @@
+# Enforce assertion to be made in a test body (`expect-expect`)
+
+Ensure that there is at least one `expect` call made in a test.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```javascript
+test('should be a test', () => {
+  console.log('no assertion');
+});
+
+test('should assert something', () => {});
+```
+
+Examples of **correct** code for this rule:
+
+```javascript
+test('should be a test', async () => {
+  await expect(page).toHaveTitle('foo');
+});
+
+test('should work with callbacks/async', async () => {
+  await test.step('step 1', async () => {
+    await expect(page).toHaveTitle('foo');
+  });
+});
+```
diff --git a/src/index.ts b/src/index.ts
index 073c3a6f..e6d1b160 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,4 @@
+import expectExpect from './rules/expect-expect';
 import maxNestedDescribe from './rules/max-nested-describe';
 import missingPlaywrightAwait from './rules/missing-playwright-await';
 import noConditionalInTest from './rules/no-conditional-in-test';
@@ -30,6 +31,7 @@ const recommended = {
   plugins: ['playwright'],
   rules: {
     'no-empty-pattern': 'off',
+    'playwright/expect-expect': 'warn',
     'playwright/max-nested-describe': 'warn',
     'playwright/missing-playwright-await': 'error',
     'playwright/no-conditional-in-test': 'warn',
@@ -87,6 +89,7 @@ export = {
     recommended,
   },
   rules: {
+    'expect-expect': expectExpect,
     'max-nested-describe': maxNestedDescribe,
     'missing-playwright-await': missingPlaywrightAwait,
     'no-conditional-in-test': noConditionalInTest,
diff --git a/src/rules/expect-expect.ts b/src/rules/expect-expect.ts
new file mode 100644
index 00000000..f21c1bd1
--- /dev/null
+++ b/src/rules/expect-expect.ts
@@ -0,0 +1,48 @@
+import { Rule } from 'eslint';
+import * as ESTree from 'estree';
+import { isExpectCall, isTest } from '../utils/ast';
+
+export default {
+  create(context) {
+    const unchecked: ESTree.CallExpression[] = [];
+
+    function checkExpressions(nodes: ESTree.Node[]) {
+      for (const node of nodes) {
+        const index =
+          node.type === 'CallExpression' ? unchecked.indexOf(node) : -1;
+
+        if (index !== -1) {
+          unchecked.splice(index, 1);
+          break;
+        }
+      }
+    }
+
+    return {
+      CallExpression(node) {
+        if (isTest(node)) {
+          unchecked.push(node);
+        } else if (isExpectCall(node)) {
+          checkExpressions(context.getAncestors());
+        }
+      },
+      'Program:exit'() {
+        unchecked.forEach((node) => {
+          context.report({ messageId: 'noAssertions', node });
+        });
+      },
+    };
+  },
+  meta: {
+    docs: {
+      category: 'Best Practices',
+      description: 'Enforce assertion to be made in a test body',
+      recommended: true,
+      url: 'https://github.com/playwright-community/eslint-plugin-playwright/tree/main/docs/rules/expect-expect.md',
+    },
+    messages: {
+      noAssertions: 'Test has no assertions',
+    },
+    type: 'problem',
+  },
+} as Rule.RuleModule;
diff --git a/test/spec/expect-expect.spec.ts b/test/spec/expect-expect.spec.ts
new file mode 100644
index 00000000..85c1dcf7
--- /dev/null
+++ b/test/spec/expect-expect.spec.ts
@@ -0,0 +1,21 @@
+import rule from '../../src/rules/expect-expect';
+import { runRuleTester } from '../utils/rule-tester';
+
+runRuleTester('expect-expect', rule, {
+  invalid: [
+    {
+      code: 'test("should fail", () => {});',
+      errors: [{ messageId: 'noAssertions' }],
+    },
+    {
+      code: 'test.skip("should fail", () => {});',
+      errors: [{ messageId: 'noAssertions' }],
+    },
+  ],
+  valid: [
+    'foo();',
+    '["bar"]();',
+    'testing("will test something eventually", () => {})',
+    'test("should pass", () => expect(true).toBeDefined())',
+  ],
+});