CODEWITHSUNDEEP
javascriptunit-testingtypescriptjestjs
Mohammad Salman
Mohammad Salman

Reputation: 33

javascript unit testing with jest: how to mock async call

I am new to TypeScript, earlier worked on Java. I am looking for java junit(Mockito) equivalent to TypeScript. In junit in each test we can define the dependency behavior and return the response as per the test case demand. is there similar way available in jest also ? in which i can simply define. when(dependencyFunction()).then(mockResponse1);

and in different test when(dependencyFunction()).then(mockResponse2);

Here is how my typescript class look like:

class ABC {
   static fun1(){
       const xyz = await dependency();
       return xyz === 'DONE';
   }
}

Here i want to write test cases in which i can define the mocked response in each test cases.

Upvotes: 0

Views: 404

Answers (1)

mina sameh
mina sameh

Reputation: 1069

from the documentation you can use mock functions for this and use mockReturnValueOnce or mockReturnValue for your responses

const myMock = jest.fn();

myMock
  .mockReturnValueOnce(10) // set the response once
  .mockReturnValueOnce('x')
  .mockReturnValue(true); // set a persistent response 

console.log(myMock(), myMock(), myMock(), myMock());
// > 10, 'x', true, true

Upvotes: 1

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