Throws InvocationTargetException while calling static method

[hemant-karwade]

Hi,

I am trying to mock some classes from LaunchDarkly JAVA Client library.

I have created following class with constructor, which I like to unit test by mocking some of

public class SampleClass { 
.........................
........................
public SampleClass(String strBaseUrl, String strProjKey, String strEnv, String strAuthToken) {
        ................................
        ...................
        **this.defaultClient = Configuration.getDefaultApiClient();**
        ,,,,,,,,,,,,,,,,,,,,,,,,
        .......................
        this.featureFlagsApiInstance = new FeatureFlagsApi(defaultClient);
        this.userApiInstance = new UsersApi(defaultClient);
    }
}

When I call this constructor in test class using PowerMock getting exception InvocationTargetException and get null instance.
TestClass:

@RunWith(PowerMockRunner.class)
@PrepareForTest(fullyQualifiedNames = "com.trmsys.tacoe.launchdarkly.utils.*")
@PowerMockIgnore("jdk.internal.reflect.*")
public class LDUtilTest2 {

  @Test
  public void testLdUtils() {
    //add behaviour of LD client library
   try{
      FeatureFlagsApi featureFlagsApiInstance = mock(FeatureFlagsApi.class);
      UsersApi userApiInstance = mock(UsersApi.class);
      **LDHelper ldHelper = new LDHelper("string", "string", "string", "string");**
      ....................................
      ...................................
    }
   catch(Exception e) {
      e.printStackTrace();
      Assert.fail();
   }
 }

Observations: From SampleClass statement "this.defaultClient = Configuration.getDefaultApiClient();" which is static method, throw this exception which cause this test failure... I tried mocking this static method too by adding following statements in test class, but result is same

   PowerMockito.mockStatic(Configuration.class);
   PowerMockito.when(Configuration.getDefaultApiClient()).thenReturn(new ApiClient());

Java module and their versions being used:

Java: 11
junit: 4.12
mockito-all: 1.10.19
powermock-api-mockito: 1.7.0
powermock-module-junit4: 1.7.0

Best Regard
Hemant