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| author | Marcia Ramos <marcia@gitlab.com> | 2019-06-26 11:39:31 +0000 |
|---|---|---|
| committer | Marcia Ramos <marcia@gitlab.com> | 2019-06-26 11:39:31 +0000 |
| commit | dfc1f1dd66c19653ecfc71b904df4a8f6ccb64e3 (patch) | |
| tree | 36624cf296b7f846b0688594d118ec54e6a61977 | |
| parent | d525c7b0275d2f8392f3646741654b29ff3cbb8a (diff) | |
| parent | 6ca0f281fbeda04cede1ba9afae7df37eefbc609 (diff) | |
| download | gitlab-ce-dfc1f1dd66c19653ecfc71b904df4a8f6ccb64e3.tar.gz | |
Merge branch 'winh-jsdom-limitations-docs' into 'master'
Document limitations of jsdom
Closes #59975
See merge request gitlab-org/gitlab-ce!30026
| -rw-r--r-- | doc/development/testing_guide/frontend_testing.md | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/doc/development/testing_guide/frontend_testing.md b/doc/development/testing_guide/frontend_testing.md index fc9b175bc8a..28ebb6f0f64 100644 --- a/doc/development/testing_guide/frontend_testing.md +++ b/doc/development/testing_guide/frontend_testing.md @@ -27,7 +27,7 @@ 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. +- Because Jest runs in a Node.js environment, it uses [jsdom](https://github.com/jsdom/jsdom) by default. See also its [limitations](#limitations-of-jsdom) below. - Jest does not have access to Webpack loaders or aliases. The aliases used by Jest are defined in its [own config](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/jest.config.js). - All calls to `setTimeout` and `setInterval` are mocked away. See also [Jest Timer Mocks](https://jestjs.io/docs/en/timer-mocks). @@ -40,6 +40,17 @@ we need to solve before being able to use Jest for all our needs. - Unhandled Promise rejections. - Calls to `console.warn`, including warnings from libraries like Vue. +### Limitations of jsdom + +As mentioned [above](#differences-to-karma), Jest uses jsdom instead of a browser for running tests. +This comes with a number of limitations, namely: + +- [No scrolling support](https://github.com/jsdom/jsdom/blob/15.1.1/lib/jsdom/browser/Window.js#L623-L625) +- [No element sizes or positions](https://github.com/jsdom/jsdom/blob/15.1.1/lib/jsdom/living/nodes/Element-impl.js#L334-L371) +- [No layout engine](https://github.com/jsdom/jsdom/issues/1322) in general + +See also the issue for [support running Jest tests in browsers](https://gitlab.com/gitlab-org/gitlab-ce/issues/58205). + ### 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). |