assertStrict

Prefer strict assertion mode from Node.js for better error messages and behavior.

✅ This rule is included in the node logical presets.

In strict assertion mode, non-strict methods like deepEqual() behave like their strict counterparts (deepStrictEqual()). Strict mode provides better error messages with diffs and more reliable equality checks, reducing the risk of false positives in tests.

import 
function assert(value: unknown, message?: string | Error): asserts value
An alias of
assert.ok
.
@since ― v0.5.9
@param ― value The input that is checked for being truthy.
assert from "assert";

import 
function assert(value: unknown, message?: string | Error): asserts value
An alias of
assert.ok
.
@since ― v0.5.9
@param ― value The input that is checked for being truthy.
assert from "node:assert";

import { 
function deepEqual(actual: unknown, expected: unknown, message?: string | Error): void
Strict assertion mode
An alias of
deepStrictEqual
.
Legacy assertion mode

Stability: 3 - Legacy: Use

deepStrictEqual
instead.
Tests for deep equality between the actual and expected parameters. Consider
using
deepStrictEqual
instead.
deepEqual
can have
surprising results.
Deep equality means that the enumerable "own" properties of child objects
are also recursively evaluated by the following rules.
@since ― v0.1.21
deepEqual } from "node:assert";

import 
function assert(value: unknown, message?: string | Error): asserts value
assert from "assert/strict";

import 
function assert(value: unknown, message?: string | Error): asserts value
assert from "node:assert/strict";

import { 
function assert.strict(value: unknown, message?: string | Error): asserts value
namespace assert.strict
export assert.strict
strict as 
function assert(value: unknown, message?: string | Error): asserts value
assert } from "node:assert";

import { 
function strict(value: unknown, message?: string | Error): asserts value
strict } from "node:assert";

Options

This rule is not configurable.

When Not To Use It

If you specifically need the non-strict behavior of assertion methods (for example, when testing legacy code that relies on coercive equality), you might choose not to enable this rule.

Equivalents in Other Linters

Biome: useNodeAssertStrict

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assertStrict

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters