I have this code

public final class TestClass {

private final SomeClass someClass;

/**
 * Singleton instance.
 */
public static final TestClass DEFAULT = new TestClass();

private TestClass() {
    this.someClass = SomeClass.builder()
            .field(getFieldFromEnv())) <---- Method that fetches from env variable, or throws exception if not present
            .build();
}

 public TestClass(SomeClass someClass) {
    this.someClass = someClass;

   ....
}

Now in order to unit test the TestClass and pass in a mock of someClass i had to create the public constructor as above. Now what is happening is that when i am creating the mock in the unit test and passing it in as

@BeforeEach
public void setup() {
    mocks = MockitoAnnotations.openMocks(this);
    testClass = new TestClass(mockSomeClass);
}

The DEFAULT singleton is getting invoked which is calling getFieldFromEnv) and as the environment variable is not set, is throwing an exception making my test class send failures.

I am wondering if there is a way to have the unit test ignore the DEFAULT constructor exception or simply not create the singleton DEFAULT as it is not needed during unit testing.