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vitest/prefer-strict-boolean-matchers Style

🛠️ An auto-fix is available for this rule.

What it does

Enforce using toBe(true) and toBe(false) over matchers that coerce types to boolean.

Why is this bad?

Truthy/falsy matchers coerce values to boolean and can hide type mistakes. Strict boolean assertions make intent explicit and avoid accidental coercion.

Examples

Examples of incorrect code for this rule:

expect(foo).toBeTruthy();
expectTypeOf(foo).toBeTruthy();
expect(foo).toBeFalsy();
expectTypeOf(foo).toBeFalsy();

Examples of correct code for this rule:

expect(foo).toBe(true);
expectTypeOf(foo).toBe(true);
expect(foo).toBe(false);
expectTypeOf(foo).toBe(false);

How to use

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

Config (.oxlintrc.json)

{
  "plugins": ["vitest"],
  "rules": {
    "vitest/prefer-strict-boolean-matchers": "error"
  }
}

Config (oxlint.config.ts)

import { defineConfig } from "oxlint";

export default defineConfig({
  plugins: ["vitest"],
  rules: {
    "vitest/prefer-strict-boolean-matchers": "error",
  },
});

CLI

oxlint --deny vitest/prefer-strict-boolean-matchers --vitest-plugin

Version

This rule was added in v1.57.0.

References

• Rule Source
• Open rule in Oxc Playground