feat: create no-unhooked-function-calls rule

Author: G-Rath

README.md

@@ -177,6 +177,7 @@ installations requiring long-term consistency.
 | [no-standalone-expect](docs/rules/no-standalone-expect.md)                   | Disallow using `expect` outside of `it` or `test` blocks            | ![recommended][] |              |
 | [no-test-prefixes](docs/rules/no-test-prefixes.md)                           | Use `.only` and `.skip` over `f` and `x`                            | ![recommended][] | ![fixable][] |
 | [no-test-return-statement](docs/rules/no-test-return-statement.md)           | Disallow explicitly returning from tests                            |                  |              |
+| [no-unhooked-function-calls](docs/rules/no-unhooked-function-calls.md)       | Checks for function calls within describes that are not in a hook   |                  |              |
 | [prefer-called-with](docs/rules/prefer-called-with.md)                       | Suggest using `toBeCalledWith()` or `toHaveBeenCalledWith()`        |                  |              |
 | [prefer-expect-assertions](docs/rules/prefer-expect-assertions.md)           | Suggest using `expect.assertions()` OR `expect.hasAssertions()`     |                  | ![suggest][] |
 | [prefer-expect-resolves](docs/rules/prefer-expect-resolves.md)               | Prefer `await expect(...).resolves` over `expect(await ...)` syntax |                  | ![fixable][] |

docs/rules/no-unhooked-function-calls.md

@@ -0,0 +1,59 @@
+# Checks for function calls within describes that are not in a hook (`no-unhooked-function-calls`)
+
+Often while writing tests you have some setup work that needs to happen before
+tests run, and you have some finishing work that needs to happen after tests
+run. Jest provides helper functions to handle this.
+
+It's common when writing tests to need to perform setup work that needs to
+happen before tests run, and finishing work after tests run.
+
+Because Jest executes all `describe` handlers in a test file _before_ it
+executes any of the actual tests, it's important to ensure setup and teardown
+work is done inside `before*` and `after*` handlers respectively, rather than
+inside the `describe` blocks.
+
+## Rule details
+
+This rule flags any function calls within test files that are directly within
+the body of a `describe`, and suggests wrapping them in one of the four
+lifecycle hooks.
+
+The following patterns are considered warnings:
+
+```js
+describe('cities', () => {
+  initializeCityDatabase();
+
+  test('city database has Vienna', () => {
+    expect(isCity('Vienna')).toBeTruthy();
+  });
+
+  test('city database has San Juan', () => {
+    expect(isCity('San Juan')).toBeTruthy();
+  });
+
+  clearCityDatabase();
+});
+```
+
+The following patterns are **not** considered warnings:
+
+```js
+describe('cities', () => {
+  beforeEach(() => {
+    initializeCityDatabase();
+  });
+
+  test('city database has Vienna', () => {
+    expect(isCity('Vienna')).toBeTruthy();
+  });
+
+  test('city database has San Juan', () => {
+    expect(isCity('San Juan')).toBeTruthy();
+  });
+
+  afterEach(() => {
+    clearCityDatabase();
+  });
+});
+```

src/__tests__/__snapshots__/rules.test.ts.snap

@@ -35,6 +35,7 @@ Object {
       "jest/no-standalone-expect": "error",
       "jest/no-test-prefixes": "error",
       "jest/no-test-return-statement": "error",
+      "jest/no-unhooked-function-calls": "error",
       "jest/prefer-called-with": "error",
       "jest/prefer-expect-assertions": "error",
       "jest/prefer-expect-resolves": "error",

src/__tests__/rules.test.ts

@@ -2,7 +2,7 @@ import { existsSync } from 'fs';
 import { resolve } from 'path';
 import plugin from '../';
 
-const numberOfRules = 48;
+const numberOfRules = 49;
 const ruleNames = Object.keys(plugin.rules);
 const deprecatedRules = Object.entries(plugin.rules)
   .filter(([, rule]) => rule.meta.deprecated)

src/rules/__tests__/no-unhooked-function-calls.test.ts

@@ -0,0 +1,146 @@
+import { TSESLint } from '@typescript-eslint/experimental-utils';
+import dedent from 'dedent';
+import resolveFrom from 'resolve-from';
+import rule from '../no-unhooked-function-calls';
+
+const ruleTester = new TSESLint.RuleTester({
+  parser: resolveFrom(require.resolve('eslint'), 'espree'),
+  parserOptions: {
+    ecmaVersion: 2017,
+  },
+});
+
+ruleTester.run('no-unhooked-function-calls', rule, {
+  valid: [
+    dedent`
+      test('it', () => {
+        //
+      });
+    `,
+    dedent`
+      describe('some tests', () => {
+        it('is true', () => {
+          expect(true).toBe(true);
+        });
+      });
+    `,
+    dedent`
+      describe('some tests', () => {
+        it('is true', () => {
+          expect(true).toBe(true);
+        });
+
+        describe('more tests', () => {
+          it('is false', () => {
+            expect(true).toBe(false);
+          });
+        });
+      });
+    `,
+    dedent`
+      describe('some tests', () => {
+        let consoleLogSpy;
+
+        beforeEach(() => {
+          consoleLogSpy = jest.spyOn(console, 'log'); 
+        });
+
+        it('prints a message', () => {
+          printMessage('hello world');
+
+          expect(consoleLogSpy).toHaveBeenCalledWith('hello world');
+        });
+      });
+    `,
+    dedent`
+      describe('some tests', () => {
+        beforeEach(() => {
+          setup();
+        });
+      });
+    `,
+    dedent`
+      beforeEach(() => {
+        initializeCityDatabase();
+      });
+
+      afterEach(() => {
+        clearCityDatabase();
+      });
+
+      test('city database has Vienna', () => {
+        expect(isCity('Vienna')).toBeTruthy();
+      });
+
+      test('city database has San Juan', () => {
+        expect(isCity('San Juan')).toBeTruthy();
+      });
+    `,
+    dedent`
+      describe('cities', () => {
+        beforeEach(() => {
+          initializeCityDatabase();
+        });
+
+        test('city database has Vienna', () => {
+          expect(isCity('Vienna')).toBeTruthy();
+        });
+
+        test('city database has San Juan', () => {
+          expect(isCity('San Juan')).toBeTruthy();
+        });
+
+        afterEach(() => {
+          clearCityDatabase();
+        });
+      });
+    `,
+  ],
+  invalid: [
+    {
+      code: dedent`
+        describe('some tests', () => {
+          setup();
+        });
+      `,
+      errors: [
+        {
+          messageId: 'useHook',
+          line: 2,
+          column: 3,
+        },
+      ],
+    },
+    {
+      code: dedent`
+        describe('some tests', () => {
+          setup();
+
+          it('is true', () => {
+            expect(true).toBe(true);
+          });
+
+          describe('more tests', () => {
+            setup();
+
+            it('is false', () => {
+              expect(true).toBe(false);
+            });
+          });
+        });
+      `,
+      errors: [
+        {
+          messageId: 'useHook',
+          line: 2,
+          column: 3,
+        },
+        {
+          messageId: 'useHook',
+          line: 9,
+          column: 5,
+        },
+      ],
+    },
+  ],
+});

src/rules/no-unhooked-function-calls.ts

@@ -0,0 +1,64 @@
+import { AST_NODE_TYPES } from '@typescript-eslint/experimental-utils';
+import {
+  createRule,
+  isDescribeCall,
+  isFunction,
+  isHook,
+  isTestCaseCall,
+} from './utils';
+
+export default createRule({
+  name: __filename,
+  meta: {
+    docs: {
+      category: 'Best Practices',
+      description:
+        'Checks for function calls within describes that are not in a hook',
+      recommended: false,
+    },
+    messages: {
+      useHook: 'This should be done within a hook',
+    },
+    type: 'suggestion',
+    schema: [],
+  },
+  defaultOptions: [],
+  create(context) {
+    return {
+      CallExpression(node) {
+        if (!isDescribeCall(node) || node.arguments.length < 2) {
+          return;
+        }
+
+        const [, testFn] = node.arguments;
+
+        if (
+          !isFunction(testFn) ||
+          testFn.body.type !== AST_NODE_TYPES.BlockStatement
+        ) {
+          return;
+        }
+
+        for (const nod of testFn.body.body) {
+          if (
+            nod.type === AST_NODE_TYPES.ExpressionStatement &&
+            nod.expression.type === AST_NODE_TYPES.CallExpression
+          ) {
+            if (
+              isDescribeCall(nod.expression) ||
+              isTestCaseCall(nod.expression) ||
+              isHook(nod.expression)
+            ) {
+              return;
+            }
+
+            context.report({
+              node: nod.expression,
+              messageId: 'useHook',
+            });
+          }
+        }
+      },
+    };
+  },
+});