Jest Difference Between toBeCalledWith and toHaveBeenCalledWith

Question

This isn't obvious from the docs but... What is the difference between toBeCalledWith and toHaveBeenCalledWith?

Answer 1

From the docs https://jestjs.io/docs/en/expect#tohavebeencalledwitharg1-arg2-

.toHaveBeenCalledWith(arg1, arg2, ...) under the alias: .toBeCalledWith()

From the source code:

https://github.com/facebook/jest/blob/b7cb5221bb06b6fe63c1a5e725ddbc1aaa82d306/packages/expect/src/spyMatchers.ts#L1128

https://github.com/facebook/jest/blob/b7cb5221bb06b6fe63c1a5e725ddbc1aaa82d306/packages/expect/src/spyMatchers.ts#L1131

//...
  toBeCalledWith: createToBeCalledWithMatcher('toBeCalledWith'),
  toHaveBeenCalled: createToBeCalledMatcher('toHaveBeenCalled'),
  toHaveBeenCalledTimes: createToBeCalledTimesMatcher('toHaveBeenCalledTimes'),
  toHaveBeenCalledWith: createToBeCalledWithMatcher('toHaveBeenCalledWith'),
//...

They are created by the createToBeCalledWithMatcher function with only a different name.

So, they are the same.

UPDATE: Here is my personal understanding of why jestjs provide these matcher APIs aliases.

jestjs builds on jasmine test runner, see Jasmine and Test Assertion Improvements

jasmine only provides a matcher - toHaveBeenCalledWith.

jestjs provides better matcher APIs over jasmine, The toBeCalledWith alias is shorter, easier to remember, and easier to use. There doesn't seem to be much semantic need for "have been"