Build a mini test runner

The challenge

Write runTests(tests) where each test is { name, fn }. Call each fn. If it throws, the test failed. Return { passed, failed, failures } where failures is an array of the failing tests’ names.

Try it

Write your answer below, then press Check my answer. Your code runs right here in your browser, and the tests tell you what works.

What the tests check

• runTests([{ name: "ok", fn: () => {} }, { name: "bad", fn: () => { throw new Error("x"); } }]) gives { passed: 1, failed: 1, failures: ["bad"] }
• runTests([]) gives { passed: 0, failed: 0, failures: [] }

Hints

Stuck? Open one hint at a time. Try again after each one.

A solution

There’s always more than one right way. Read it, make sure you understand it, then try writing it yourself without looking.

function runTests(tests) {
  const failures = [];
  for (const t of tests) {
    try {
      t.fn();
    } catch (error) {
      failures.push(t.name);
    }
  }
  return { passed: tests.length - failures.length, failed: failures.length, failures };
}

Learn what you need

This exercise uses what Junior Year: Modules, Node.js & npm: Working Like a Pro teaches. Read those notes first if any of it is new.