feat: create no-conditional-in-test rule

README.md

@@ -158,6 +158,7 @@ installations requiring long-term consistency.
 | [no-alias-methods](docs/rules/no-alias-methods.md) | Disallow alias methods | ![style][] | ![fixable][] |
 | [no-commented-out-tests](docs/rules/no-commented-out-tests.md) | Disallow commented out tests | ![recommended][] | |
 | [no-conditional-expect](docs/rules/no-conditional-expect.md) | Prevent calling `expect` conditionally | ![recommended][] | |
+| [no-conditional-in-test](docs/rules/no-conditional-in-test.md) | Disallow conditional logic in tests | | |
 | [no-deprecated-functions](docs/rules/no-deprecated-functions.md) | Disallow use of deprecated functions | ![recommended][] | ![fixable][] |
 | [no-disabled-tests](docs/rules/no-disabled-tests.md) | Disallow disabled tests | ![recommended][] | |
 | [no-done-callback](docs/rules/no-done-callback.md) | Avoid using a callback in asynchronous tests and hooks | ![recommended][] | ![suggest][] |

docs/rules/no-conditional-in-test.md

@@ -0,0 +1,79 @@
+# Disallow conditional logic in tests (`no-conditional-in-test`)
+
+Conditional logic in tests is usually an indication that a test is attempting to
+cover too much, and not testing the logic it intends to. Each branch of code
+executing within a conditional statement will usually be better served by a test
+devoted to it.
+
+## Rule Details
+
+This rule reports on any use of a conditional statement such as `if`, `switch`,
+and ternary expressions.
+
+Examples of **incorrect** code for this rule:
+
+```js
+it('foo', () => {
+ if (true) {
+ doTheThing();
+ }
+});
+
+it('bar', () => {
+ switch (mode) {
+ case 'none':
+ generateNone();
+ case 'single':
+ generateOne();
+ case 'multiple':
+ generateMany();
+ }
+
+ expect(fixtures.length).toBeGreaterThan(-1);
+});
+
+it('baz', async () => {
+ const promiseValue = () => {
+ return something instanceof Promise
+ ? something
+ : Promise.resolve(something);
+ };
+
+ await expect(promiseValue()).resolves.toBe(1);
+});
+```
+
+Examples of **correct** code for this rule:
+
+```js
+describe('my tests', () => {
+ if (true) {
+ it('foo', () => {
+ doTheThing();
+ });
+ }
+});
+
+beforeEach(() => {
+ switch (mode) {
+ case 'none':
+ generateNone();
+ case 'single':
+ generateOne();
+ case 'multiple':
+ generateMany();
+ }
+});
+
+it('bar', () => {
+ expect(fixtures.length).toBeGreaterThan(-1);
+});
+
+const promiseValue = something => {
+ return something instanceof Promise ? something : Promise.resolve(something);
+};
+
+it('baz', async () => {
+ await expect(promiseValue()).resolves.toBe(1);
+});
+```

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

@@ -16,6 +16,7 @@ Object {
  "jest/no-alias-methods": "error",
  "jest/no-commented-out-tests": "error",
  "jest/no-conditional-expect": "error",
+ "jest/no-conditional-in-test": "error",
  "jest/no-deprecated-functions": "error",
  "jest/no-disabled-tests": "error",
  "jest/no-done-callback": "error",

src/__tests__/rules.test.ts

@@ -2,7 +2,7 @@ import { existsSync } from 'fs';
 import { resolve } from 'path';
 import plugin from '../';
 
-const numberOfRules = 45;
+const numberOfRules = 46;
 const ruleNames = Object.keys(plugin.rules);
 const deprecatedRules = Object.entries(plugin.rules)
  .filter(([, rule]) => rule.meta.deprecated)