biome-plugin-no-if-in-tests

A Biome plugin that forbids if statements and try-catch blocks in test files.

Why?

Tests should be deterministic and straightforward. Conditional logic in tests often indicates:

• Tests that don't always run the same assertions
• Hidden complexity that makes tests harder to understand
• Code that should be refactored into separate test cases

Instead of try-catch, use your testing framework's built-in assertions like t.throws() (AVA) or expect(...).toThrow() (Jest).

Installation

npm install --save-dev biome-plugin-no-if-in-tests

Usage

Add the plugin rules to your biome.json:

{
  "$schema": "https://biomejs.dev/schemas/1.9.0/schema.json",
  "plugins": [
    "./node_modules/biome-plugin-no-if-in-tests/rules/no-if-in-tests.grit",
    "./node_modules/biome-plugin-no-if-in-tests/rules/no-try-catch-in-tests.grit"
  ]
}

Run Biome with experimental plugins enabled:

biome lint --use-experimental-plugins .

Rules

no-if-in-tests

Forbids if and if-else statements in files matching *test.ts or *test.js.

// Bad
test("should work", (t) => {
  if (condition) {
    t.true(value);
  }
});

// Good
test("should work when condition is true", (t) => {
  t.true(value);
});

test("should work when condition is false", (t) => {
  t.false(value);
});

no-try-catch-in-tests

Forbids try-catch blocks in test files.

// Bad
test("should throw", (t) => {
  try {
    throwingFunction();
  } catch (error) {
    t.is(error.message, "error");
  }
});

// Good
test("should throw", (t) => {
  t.throws(() => throwingFunction(), { message: "error" });
});

License

MIT