Filtering Tests.md

Sometimes, we don't want all of our tests to run. Some times we only want certain tests to run.

• test.skip: Skip this test for now.
• test.only: Only run this and any other test that uses .only.
• test.todo: Note to self—I still need to write this test.
• test.fails: Yea, I know this one fails. Don't blow up the rest of the test run, please.

Only Run Certain Tests

You can use .only if you want to run only a few of your tests.

it.only('should work', () => {
  expect(true).toBe(true);
});

test('works with "test" as well', () => {
  expect(true).not.toBe(false);
});

Skip Certain Tests

Alternatively, you can skip tests that you don't want to run right now.

import { it, expect, test } from 'vitest';

it('should work', () => {
  expect(true).toBe(true);
});

test.skip('works with "test" as well', () => {
  expect(true).not.toBe(false);
});

Alternatively, you can use todo to signify that you want to skip this test for now, but it's because you intend to write an implementation for it… eventually.

it('should work', () => {
  expect(true).toBe(true);
});

test.todo('works with "test" as well', () => {
  expect(true).not.toBe(false);
});

Conditionally Run Tests

You saw some of these (well, the first two) before, but I'll call them out just in case you missed them:

• test.skipIf: Only skip this one if I had you a truthy value.
• test.runIf: Only run this test if I give you a truthy value.
• test.concurrent: Run this test in parallel with any other test using .concurrent. We'll cover this in Parallelizing Tests.
• test.each: I want to generate a bunch of tests. We'll cover this in Parameterizing Tests.

Examples

test.runIf(process.env.NODE_ENV === 'development')(
  'it should run in development',
  () => {
    expect(process.env.NODE_ENV).toBe('development');
  },
);

test.skipIf(process.env.NODE_ENV !== 'test')('it should run in test', () => {
  expect(process.env.NODE_ENV).toBe('test');
});

Dynamically Filter Tests

When Vitest (or Jest, for that matter) are watching for changes, you can press the h key to open up some options:

• press a to rerun all tests
• press f to rerun only failed tests
• press u to update snapshot
• press p to filter by a filename
• press t to filter by a test name regex pattern
• press q to quit

Filtering by test name can be super useful if you're like me and don't trust yourself to remember to remove your skip and only annotations. (Although, we'll talk more about this later.)

Filter Tests By Filename When Starting Up

npm test foo

This will run foo.test.ts, but not bar.test.ts.

vitest related

This will run tests related to whatever file you provide. (So, this is like filter but adds a few more to the mix.)

vitest --changed

Runs tests related to files that changed. Out of the box, this will be against any uncommitted files. But, you can also do cool stuff like --changed HEAD~1 or give it a branch name to compare to or a particular commit.

👩🏾‍🔬 Experiment

Inside of examples/getting-started:

1. Run npx vitest --run and look at which test files run.
2. Run npx vitest words --run and look at which test files run.
3. Run npx vitest related ./math.ts --run and look at which test files run.
4. Run npx vitest related ./exponent.ts --run and look at which test files run.
5. Assuming you don't have any unstaged or uncommitted changes, run npx vitest --changed HEAD --run and look at which test files—umm—didn't run.
6. Make a change to words.ts (or any other file, really) and then run npx vitest --changed HEAD --run and see what tests run.