jest/prefer-mock-promise-shorthand Style

🛠️ An auto-fix is available for this rule for some violations.

What it does

When working with mocks of functions that return promises, Jest provides some API sugar functions to reduce the amount of boilerplate you have to write. These methods should be preferred when possible.

Example

// invalid
jest.fn().mockImplementation(() => Promise.resolve(123));
jest.spyOn(fs.promises, "readFile").mockReturnValue(Promise.reject(new Error("oh noes!")));

myFunction
  .mockReturnValueOnce(Promise.resolve(42))
  .mockImplementationOnce(() => Promise.resolve(42))
  .mockReturnValue(Promise.reject(new Error("too many calls!")));

// valid

jest.fn().mockResolvedValue(123);
jest.spyOn(fs.promises, "readFile").mockRejectedValue(new Error("oh noes!"));

myFunction.mockResolvedValueOnce(42).mockResolvedValueOnce(42).mockRejectedValue(new Error("too many calls!"));

References

• Rule Source