noMisplacedAssertion

import { Tabs, TabItem } from '@astrojs/starlight/components';

<Tabs> <TabItem label="JavaScript (and super languages)" icon="seti:javascript"> ## Summary - Rule available since: `v1.8.0` - Diagnostic Category: [`lint/suspicious/noMisplacedAssertion`](/reference/diagnostics#diagnostic-category) - This rule isn't recommended, so you need to enable it. - This rule doesn't have a fix. - The default severity of this rule is [**warning**](/reference/diagnostics#warning). - Sources: - Inspired from [`jest/no-standalone-expect`](https://github.com/jest-community/eslint-plugin-jest/blob/main/docs/rules/no-standalone-expect.md) - Inspired from [`vitest/no-standalone-expect`](https://github.com/vitest-dev/eslint-plugin-vitest/blob/main/docs/rules/no-standalone-expect.md)

How to configure

json

{
	"linter": {
		"rules": {
			"suspicious": {
				"noMisplacedAssertion": "error"
			}
		}
	}
}

Description

Checks that the assertion function, for example expect, is placed inside an it() function call.

Placing (and using) the expect assertion function can result in unexpected behaviors when executing your testing suite.

The rule will check for the following assertion calls:

expect
assert
assertEquals

However, the rule will ignore the following assertion calls:

expect.any
expect.anything
expect.closeTo
expect.arrayContaining
expect.objectContaining
expect.stringContaining
expect.stringMatching
expect.extend
expect.addEqualityTesters
expect.addSnapshotSerializer

If the assertion function is imported, the rule will check if they are imported from:

"chai"
"node:assert"
"node:assert/strict"
"bun:test"
"vitest"
Deno assertion module URL

Check the options if you need to change the defaults.

Examples

Invalid

describe("describe", () => {
    expect()
})

<pre class="language-text"><code class="language-text">code-block.js:2:5 <a href="https://biomejs.dev/linter/rules/no-misplaced-assertion">lint/suspicious/noMisplacedAssertion</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ The assertion isn't inside a it(), test() or Deno.test() function call. 1 │ describe("describe", () => { > 2 │ expect() │ ^^^^^^ 3 │ }) 4 │ ℹ This will result in unexpected behaviours from your test suite. ℹ Move the assertion inside a it(), test() or Deno.test() function call. </code></pre>

import assert from "node:assert";
describe("describe", () => {
    assert.equal()
})

<pre class="language-text"><code class="language-text">code-block.js:3:5 <a href="https://biomejs.dev/linter/rules/no-misplaced-assertion">lint/suspicious/noMisplacedAssertion</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ The assertion isn't inside a it(), test() or Deno.test() function call. 1 │ import assert from "node:assert"; 2 │ describe("describe", () => { > 3 │ assert.equal() │ ^^^^^^ 4 │ }) 5 │ ℹ This will result in unexpected behaviours from your test suite. ℹ Move the assertion inside a it(), test() or Deno.test() function call. </code></pre>

import {test, expect} from "bun:test";
expect(1, 2)

<pre class="language-text"><code class="language-text">code-block.js:2:1 <a href="https://biomejs.dev/linter/rules/no-misplaced-assertion">lint/suspicious/noMisplacedAssertion</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ The assertion isn't inside a it(), test() or Deno.test() function call. 1 │ import {test, expect} from "bun:test"; > 2 │ expect(1, 2) │ ^^^^^^ 3 │ ℹ This will result in unexpected behaviours from your test suite. ℹ Move the assertion inside a it(), test() or Deno.test() function call. </code></pre>

import {assertEquals} from "https://deno.land/[email protected]/assert/mod.ts";

assertEquals(url.href, "https://deno.land/foo.js");
Deno.test("url test", () => {
    const url = new URL("./foo.js", "https://deno.land/");
});

<pre class="language-text"><code class="language-text">code-block.js:3:1 <a href="https://biomejs.dev/linter/rules/no-misplaced-assertion">lint/suspicious/noMisplacedAssertion</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⚠ The assertion isn't inside a it(), test() or Deno.test() function call. 1 │ import {assertEquals} from "https://deno.land/[email protected]/assert/mod.ts"; 2 │ > 3 │ assertEquals(url.href, "https://deno.land/foo.js"); │ ^^^^^^^^^^^^ 4 │ Deno.test("url test", () => { 5 │ const url = new URL("./foo.js", "https://deno.land/"); ℹ This will result in unexpected behaviours from your test suite. ℹ Move the assertion inside a it(), test() or Deno.test() function call. </code></pre>

Valid

import assert from "node:assert";
describe("describe", () => {
    it("it", () => {
        assert.equal()
    })
})

describe("describe", () => {
    it("it", () => {
        expect()
    })
})

test.each([1, 2, 3])('test', (a, b, expected) => {
    expect(a + b).toBe(expected)
})

import { waitFor } from '@testing-library/react';
await waitFor(() => {
  expect(111).toBe(222);
});

</TabItem> </Tabs>

How to configure

Description

Examples

Invalid

Valid

Related links