CODEWITHSUNDEEP
javascriptnode.jsunit-testingjestjs
Joey Yi Zhao
Joey Yi Zhao

Reputation: 42454

How does jest mock the module a dependency requires?

I know how to mock a module through jest in my unit tests. But my problem is that how I can mock a module which is required by a dependency. For example, I have dependency A defined in my package.json file while A dependents on B. So in my unit tests how I can mock B which is used by A?

Upvotes: 0

Views: 1006

Answers (1)

skyboyer
skyboyer

Reputation: 23705

jest.mock works well for any-level dependency. So

jet.mock('B');

at the start of test for A will work.

Also you can provide auto-mocks by placing mocks into special folder named __mocks__. So once B is in node_modules we need to have mock in sibling __mocks__ directory next to node_modules like

 -   node_modules
 --  B
 --- index.js
 -   __mocks__
 --  B.js

And finally beware of

Warning: If we want to mock Node's core modules (e.g.: fs or path), then explicitly calling e.g. jest.mock('path') is required, because core Node modules are not mocked by default.

Upvotes: 1

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