100 lines
2.1 KiB
Markdown
100 lines
2.1 KiB
Markdown
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# Disallow using `expect` outside of `it` or `test` blocks (`no-standalone-expect`)
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Prevents `expect` statements outside of a `test` or `it` block. An `expect`
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within a helper function (but outside of a `test` or `it` block) will not
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trigger this rule.
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## Rule Details
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This rule aims to eliminate `expect` statements that will not be executed. An
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`expect` inside of a `describe` block but outside of a `test` or `it` block or
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outside a `describe` will not execute and therefore will trigger this rule. It
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is viable, however, to have an `expect` in a helper function that is called from
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within a `test` or `it` block so `expect` statements in a function will not
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trigger this rule.
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Statements like `expect.hasAssertions()` will NOT trigger this rule since these
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calls will execute if they are not in a test block.
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Examples of **incorrect** code for this rule:
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```js
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// in describe
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describe('a test', () => {
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expect(1).toBe(1);
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});
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// below other tests
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describe('a test', () => {
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it('an it', () => {
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expect(1).toBe(1);
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});
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expect(1).toBe(1);
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});
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```
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Examples of **correct** code for this rule:
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```js
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// in it block
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describe('a test', () => {
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it('an it', () => {
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expect(1).toBe(1);
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});
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});
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// in helper function
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describe('a test', () => {
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const helper = () => {
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expect(1).toBe(1);
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};
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it('an it', () => {
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helper();
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});
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});
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describe('a test', () => {
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expect.hasAssertions(1);
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});
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```
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\*Note that this rule will not trigger if the helper function is never used even
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thought the `expect` will not execute. Rely on a rule like no-unused-vars for
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this case.
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### Options
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#### `additionalTestBlockFunctions`
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This array can be used to specify the names of functions that should also be
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treated as test blocks:
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```json
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{
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"rules": {
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"jest/no-standalone-expect": [
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"error",
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{ "additionalTestBlockFunctions": ["each.test"] }
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]
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}
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}
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```
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The following is _correct_ when using the above configuration:
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```js
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each([
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[1, 1, 2],
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[1, 2, 3],
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[2, 1, 3],
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]).test('returns the result of adding %d to %d', (a, b, expected) => {
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expect(a + b).toBe(expected);
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});
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```
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## When Not To Use It
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Don't use this rule on non-jest test files.
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