1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
---
name: Migrate from Jest to Bun's test runner
---
In many cases, Bun's test runner can run Jest test suites with no code changes. Just run `bun test` instead of `npx jest`, `yarn test`, etc.
```sh-diff
- $ npx jest
- $ yarn test
+ $ bun test
```
---
There's often no need for code changes.
- Bun internally re-writes imports from `@jest/globals` to use the `bun:test` equivalents.
- If you're relying on Jest to inject `test`, `expect`, etc. as globals, Bun does that too.
But if you'd rather switch to the `bun:test` imports, you can do that too.
```ts-diff
- import {test, expect} from "@jest/globals";
+ import {test, expect} from "bun:test";
```
---
Bun implements the vast majority of Jest's matchers, but compatibility isn't 100% yet. Refer to the full compatibility table at [Docs > Test runner > Writing tests](/docs/test/writing#matchers).
Some notable missing features:
- `expect.extend()`
- `expect().toMatchInlineSnapshot()`
- `expect().toHaveBeenCalledWith()`
- `expect().toHaveReturned()`
---
If you're using `testEnvironment: "jsdom"` to run your tests in a browser-like environment, you should follow the [DOM testing with Bun and happy-dom](/guides/test/happy-dom) guide to inject browser APIs into the global scope. This guide relies on [`happy-dom`](https://github.com/capricorn86/happy-dom), which is a leaner and faster alternative to [`jsdom`](https://github.com/jsdom/jsdom).
At the moment jsdom does not work in Bun due to its internal use of V8 APIs. Track support for it [here](https://github.com/oven-sh/bun/issues/3554).
```toml#bunfig.toml
[test]
preload = ["./happy-dom.ts"]
```
---
Replace `bail` in your Jest config with the `--bail` CLI flag.
<!-- ```ts-diff
- import type {Config} from 'jest';
-
- const config: Config = {
- bail: 3
- };
``` -->
```sh-diff
$ bun test --bail 3
```
---
Replace `collectCoverage` with the `--coverage` CLI flag.
<!-- ```ts-diff
- import type {Config} from 'jest';
-
- const config: Config = {
- collectCoverageFrom: [
- '**/*.{js,jsx}',
- '!**/node_modules/**',
- '!**/vendor/**',
- ],
- };
``` -->
```sh
$ bun test --coverage
```
---
Replace `testTimeout` with the `--test-timeout` CLI flag.
```sh
$ bun test --timeout 10000
```
---
Many other flags become irrelevant or obsolete when using `bun test`.
- `transform` — Buns supports TypeScript & JSX. Other file types can be configured with [Plugins](/docs/runtime/plugins).
- `extensionsToTreatAsEsm`
- `haste` — Bun uses it's own internal source maps
- `watchman`, `watchPlugins`, `watchPathIgnorePatterns` — use `--watch` to run tests in watch mode
- `verbose` — set `logLevel: "debug"` in [`bunfig.toml`](/docs/runtime/bunfig#loglevel)
---
Settings that aren't mentioned here are not supported or have no equivalent. Please [file a feature request](https://github.com/oven-sh/bun) if something important is missing.
---
See also:
- [Mark a test as a todo](/guides/test/todo-tests)
- [Docs > Test runner > Writing tests](/docs/test/writing)
|
