How would you test a method that returns a void during a JUnit test?

How would you test a method that returns a void during a JUnit test?

Using the verify() method

1. Mockito provides us with a verify() method which lets us verify whether the mock void method is being called or not.
2. It lets us check the number of methods invocations. So if the method invocation returns to be zero we would know that our mock method is not being called.

How do you test a function that does not return anything?

2 Answers

1. If your function is supposed to assert something and raise an error, give it wrong information and check if it does raise the right error.
2. If your function takes an object and modifies it, test if the new state of your object is as expected.

Do nothing when a method is called Mockito?

doNothing: Is the easiest of the list, basically it tells Mockito to do nothing when a method in a mock object is called. Sometimes used in void return methods or method that does not have side effects, or are not related to the unit testing you are doing.

Is a * void method * and it * Cannot * be stubbed with a * return value?

MockitoException: `’setResponseTimeStampUtc’` is a *void method* and it *cannot* be stubbed with a *return value*! Voids are usually stubbed with Throwables: doThrow(exception).

How do you mock a void method to do nothing?

How to mock void methods with mockito – there are two options:

1. doAnswer – If we want our mocked void method to do something (mock the behavior despite being void).
2. doThrow – Then there is Mockito. doThrow() if you want to throw an exception from the mocked void method.

How to unit test a method that has void as return type?

Some options: Return a type anyway, even though you don’t use it. Or expose a property with the result. This are design changes that are only neccesary for testing. I’m sure that’s not what we want.

Is it possible to test a void in Java?

It is possible to test methods that don’t return anything (void), but you must test that method’s side effects. It should have some side effects, otherwise such a method is useless. The side effect here is that al is changed.

How to test a method with a return type in Java?

The side effect here is that al is changed. As written, this class doesn’t have any other methods that expose al. Add a getter method that returns either the ArrayList or a specific element of the ArrayList. Then your test method can call the getter method to retrieve the value (s) and compare it (them) with the expected value (s).

How are methods without parameters tested in Java?

Methods without parameters are used for their return value or for their side effects. Therefore, testing of these methods consists of these three steps: The last step can check either the new state of the object being tested, or the results of its work in the overall environment of the system.