Org.mockito.exceptions.base.mockitoexception: failed to release mocks

The exception org.mockito.exceptions.base.MockitoException: Failed to release mocks occurs when Mockito fails to release the mocks after a test run. This can happen due to several reasons, such as a misconfiguration or misuse of Mockito.

To understand this exception, let’s consider an example. Suppose we have a class called “Calculator” with a method “add” which adds two numbers:

    
      public class Calculator {
          public int add(int a, int b) {
              return a + b;
          }
      }
    
  

Now, let’s write a test using Mockito to mock the Calculator class:

    
      import org.junit.jupiter.api.Test;
      import org.mockito.Mock;
      import org.mockito.Mockito;

      import static org.junit.jupiter.api.Assertions.assertEquals;
      import static org.mockito.Mockito.when;
      import static org.mockito.MockitoAnnotations.openMocks;

      public class CalculatorTest {
          @Mock
          private Calculator calculator;

          @Test
          public void testAdd() {
              openMocks(this); // Initialize the mocks

              // Configure the mock behavior
              when(calculator.add(2, 3)).thenReturn(5);

              // Test the method using the mock
              assertEquals(5, calculator.add(2, 3));

              // Verify the method was called
              Mockito.verify(calculator).add(2, 3);
          }
      }
    
  

In the above example, we use the @Mock annotation to create a mock of the Calculator class. We then configure the mock to return 5 when the add method is called with arguments 2 and 3. Finally, we assert that the result of the add method is 5 and verify that the add method was called with arguments 2 and 3.

After running this test, Mockito should release the mock gracefully. However, if Mockito fails to release the mocks, the org.mockito.exceptions.base.MockitoException: Failed to release mocks exception will be thrown.

To resolve this issue, there are a few things you can check:

1. Make sure you are using the latest version of Mockito. Older versions of Mockito may have some issues related to releasing mocks.
2. Ensure that you are using the proper annotations to initialize and close the mocks. In the example above, we use the openMocks(this) method to initialize the mocks and Mockito.verify or other methods to close the mocks.
3. Check if there are any misconfigurations or misuse of Mockito in your test code. For example, make sure you are not accidentally configuring the same mock multiple times or incorrectly configuring the behavior of a mock.

By following these guidelines and correcting any misconfigurations or misuses, you should be able to resolve the org.mockito.exceptions.base.MockitoException: Failed to release mocks exception in your code.