multiple asynchronous tests and expectation

I have multiple tests and each test is testing the same asynchronous method for different results with given parameters.

I found out for asynchronous tests we have to declare an expectation, wait for expectation, and fulfil the expectation. This is fine. Each test works out correctly when done separately, but when I try to run the whole test class some tests pass and others crash or fail when they run and pass normally.

I've looked all over online for "swift 3 multiple tests with expectation" and everyone who explains expectation only ever has an example in one test method. Is it not possible to have expectations in multiple methods in the same class?

The setup in each test method is something like:

func testLoginWrongUsernameOrPasswordFailure() {

  let expect = expectation(description: "testing for incorrect credentials")

  viewModel.loginWith(username: "qwerty", password: "qwerty", completion: { loginCompletion in

      do {
        try loginCompletion()
          XCTFail("Wrong Login didn't error")
          expect.fulfill()
        } catch let error {
          XCTAssertEqual(error as? LoginError, LoginError.wrongCredentials)
          expect.fulfill()
        }
      })

      waitForExpectations(timeout: 10) { error in
        XCTAssertNil(error)
      }
}

As far as I'm aware, this is the correct use of expectation.