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| author | Winnie Hellmann <winnie@gitlab.com> | 2019-05-08 21:20:21 +0200 |
|---|---|---|
| committer | Winnie Hellmann <winnie@gitlab.com> | 2019-05-20 12:58:38 +0200 |
| commit | f25d2ca6aec1b7804aa3dd872b669c2101a714e0 (patch) | |
| tree | 62312d0290f9db415bda9084bb02d89d47986501 | |
| parent | 9d4450263fd7dc53dafd62389871d8b1fcea5e1a (diff) | |
| download | gitlab-ce-winh-jest-differences-docs.tar.gz | |
Document the differences between Karma and Jest setupwinh-jest-differences-docs
| -rw-r--r-- | doc/development/testing_guide/frontend_testing.md | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/doc/development/testing_guide/frontend_testing.md b/doc/development/testing_guide/frontend_testing.md index f58a8dcbcdc..09641832050 100644 --- a/doc/development/testing_guide/frontend_testing.md +++ b/doc/development/testing_guide/frontend_testing.md @@ -15,10 +15,8 @@ information on general testing practices at GitLab. ## Jest -GitLab has started to migrate tests to the [Jest](https://jestjs.io) -testing framework. You can read a [detailed evaluation](https://gitlab.com/gitlab-org/gitlab-ce/issues/49171) -of Jest compared to our use of Karma and Jasmine. In summary, it will allow us -to improve the performance and consistency of our frontend tests. +We have started to migrate frontend tests to the [Jest](https://jestjs.io) testing framework (see also the corresponding +[epic](https://gitlab.com/groups/gitlab-org/-/epics/895)). Jest tests can be found in `/spec/frontend` and `/ee/spec/frontend` in EE. @@ -26,6 +24,17 @@ It is not yet a requirement to use Jest. You can view the [epic](https://gitlab.com/groups/gitlab-org/-/epics/873) of issues we need to solve before being able to use Jest for all our needs. +### Differences to Karma + +- Jest runs in a Node.js environment, not in a browser. Support for running Jest tests in a browser [is planned](https://gitlab.com/gitlab-org/gitlab-ce/issues/58205). +- Because Jest runs in a Node.js environment, it uses [jsdom](https://github.com/jsdom/jsdom) by default. +- All calls to `setTimeout` and `setInterval` are mocked away. See also [Jest Timer Mocks](https://jestjs.io/docs/en/timer-mocks). +- `rewire` is not required because Jest supports mocking modules. See also [Manual Mocks](https://jestjs.io/docs/en/manual-mocks). +- The following will cause tests to fail in Jest: + - Unmocked requests. + - Unhandled Promise rejections. + - Calls to `console.warn`, including warnings from libraries like Vue. + ### Debugging Jest tests Running `yarn jest-debug` will run Jest in debug mode, allowing you to debug/inspect as described in the [Jest docs](https://jestjs.io/docs/en/troubleshooting#tests-are-failing-and-you-don-t-know-why). |