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|
Like the runtime, `bun:test` also supports `--preload` scripts. These scripts are loaded before any tests are run. This is useful for setting up test fixtures, mocking, and configuring the test environment.
{% codetabs }
```ts#preloaded.ts
import { beforeAll, beforeEach, afterEach, afterAll } from "bun:test";
beforeAll(() => {
console.log("beforeAll");
});
beforeEach(() => {
console.log("beforeEach");
});
afterEach(() => {
console.log("afterEach");
});
afterAll(() => {
console.log("afterAll");
});
```
{% /codetabs %}
Test file:
```ts
import { expect, test } from "bun:test";
test("1 + 1", () => {
expect(1 + 1).toEqual(2);
console.log("1 + 1");
});
```
Run the test with `--preload`:
```sh
$ bun test --preload=preloaded.ts
```
It outputs:
```sh
beforeAll
beforeEach
1 + 1
afterEach
afterAll
```
## List of lifecycle hooks
The following lifecycle hooks are available in `--preload`:
| Hook | Description |
| ------------ | --------------------------- |
| `beforeAll` | Runs once before all tests. |
| `beforeEach` | Runs before each test. |
| `afterEach` | Runs after each test. |
| `afterAll` | Runs once after all tests. |
## Configuration
To save yourself from having to type `--preload` every time you run tests, you can add it to your `bunfig.toml`:
```toml
[test]
preload = ["./preloaded.ts"]
```
## Loaders & Resolvers
{% note %}
Plugin support is not implemented yet. **There is a bug and this feature is not working**.
{% /note %}
`bun:test` supports the same plugin API as bun's runtime and bun's bundler. See [Plugins](docs/bundler/plugins#usage) for more information.
## Example loader
{% codetab }
```ts#loader.ts
import { plugin } from 'bun';
plugin({
name: 'My loader',
setup(build) {
build.onResolve({ filter: /\.txt$/ }, (args) => {
return {
path: args.path,
namespace: 'my-loader',
};
});
build.onLoad({ filter: /my-loader:.txt$/ }, (args) => {
return {
contents: 'Hello world!',
loader: 'text',
};
});
},
});
```
{% /codetab %}
Now in your test file, you can import `.txt` files:
```ts#my-test.test.ts
import { expect, test } from "bun:test";
import text from "./hello.txt";
test("text is 'Hello world!'", () => {
expect(text).toEqual("Hello world!");
});
```
To run the test, you need to add `loader.ts` to `preload`:
```toml
[test]
preload = ["loader.ts"]
```
Or you can pass --preload to the command line:
```sh
$ bun test --preload=loader.ts
```
TODO: `expect.extend`
|
