# Mark a test as a "todo" with the Bun test runner

To remind yourself to write a test later, use the `test.todo` function. An implementation isn't required.

```ts test.test.ts icon="/icons/typescript.svg"
import { test } from "bun:test";

// write this later
test.todo("parses durations like 1h30m");
```

---

The `bun test` output reports the number of `todo` tests.

```sh terminal icon="terminal"
bun test
```

```txt
test.test.ts:
✎ parses durations like 1h30m

 0 pass
 1 todo
 0 fail
Ran 1 test across 1 file. [6.00ms]
```

---

You can also write the test before the code it tests exists. Here `parseDuration` is still a stub, and the todo test records what it should eventually do. `bun test` reports this test as `todo` too, without running its body.

```ts test.test.ts icon="/icons/typescript.svg"
import { test, expect } from "bun:test";

// Not written yet; the todo test below says what it should do.
function parseDuration(input: string): number {
  throw new Error("not implemented");
}

test.todo("parses durations like 1h30m", () => {
  expect(parseDuration("1h30m")).toBe(5400);
});
```

---

Pass `--todo` to run the bodies of todo tests. A todo test is _expected to fail_: while `parseDuration` is unimplemented, Bun prints the error, still counts the test as `todo`, and exits with code `0`.

```sh terminal icon="terminal"
bun test --todo
```

```txt
test.test.ts:
1 | import { test, expect } from "bun:test";
2 |
3 | // Not written yet; the todo test below says what it should do.
4 | function parseDuration(input: string): number {
5 |   throw new Error("not implemented");
                                       ^
error: not implemented
      at parseDuration (/path/to/test.test.ts:5:36)
      at <anonymous> (/path/to/test.test.ts:9:10)
✎ parses durations like 1h30m [0.16ms]

 0 pass
 1 todo
 0 fail
Ran 1 test across 1 file. [5.00ms]
```

---

Once you implement `parseDuration` and the body passes, `bun test --todo` reports the test as a failure and exits with a non-zero code. That is the signal to remove `.todo` and turn it into a regular test.

```txt
test.test.ts:
✗ parses durations like 1h30m [0.19ms]
  ^ this test is marked as todo but passes. Remove `.todo` if tested behavior now works

 0 pass
 1 fail
 1 expect() calls
Ran 1 test across 1 file. [5.00ms]
$ echo $?
1 # this is the exit code of the previous command
```

---

See also:

- [Skip a test](/guides/test/skip-tests)
- [Writing tests](/test/writing-tests)