jest/prefer-strict-equal Style

🛠️ An auto-fix is available for this rule.

What it does

This rule triggers a warning if toEqual() is used to assert equality.

Why is this bad?

The toEqual() matcher performs a deep equality check but ignores undefined values in objects and arrays. This can lead to false positives where tests pass when they should fail. toStrictEqual() provides more accurate comparison by checking for undefined values.

Examples

Examples of incorrect code for this rule:

expect({ a: "a", b: undefined }).toEqual({ a: "a" });

Examples of correct code for this rule:

expect({ a: "a", b: undefined }).toStrictEqual({ a: "a" });

How to use

To enable this rule in the CLI or using the config file, you can use:

CLI

oxlint --deny jest/prefer-strict-equal --jest-plugin

Config (.oxlintrc.json)

{
  "plugins": ["jest"],
  "rules": {
    "jest/prefer-strict-equal": "error"
  }
}

References

• Rule Source