@Test
  public void testDigitsAuthConfigBuilder_partialParamSuccess() {
    final DigitsAuthConfig.Builder digitsAuthConfigBuilder =
        new DigitsAuthConfig.Builder().withAuthCallBack(callback);

    final DigitsAuthConfig digitsAuthConfig = digitsAuthConfigBuilder.build();
    assertEquals(callback, digitsAuthConfig.authCallback);
    assertEquals(false, digitsAuthConfig.isEmailRequired);
    assertEquals("", digitsAuthConfig.phoneNumber);
  }
 @Test
 public void testDigitsAuthConfigBuilder_nullCallback() {
   final DigitsAuthConfig.Builder digitsAuthConfigBuilder =
       new DigitsAuthConfig.Builder()
           .withPhoneNumber(TestConstants.PHONE)
           .withThemeResId(TestConstants.THEME_ID)
           .withEmailCollection();
   try {
     digitsAuthConfigBuilder.build();
   } catch (IllegalArgumentException ex) {
     assertEquals("AuthCallback must not be null", ex.getMessage());
   }
 }
  @Test
  public void testDigitsAuthConfigBuilder_allParamSuccess() {
    final DigitsAuthConfig.Builder digitsAuthConfigBuilder =
        new DigitsAuthConfig.Builder()
            .withPhoneNumber(TestConstants.PHONE)
            .withThemeResId(TestConstants.THEME_ID)
            .withAuthCallBack(callback)
            .withEmailCollection();

    final DigitsAuthConfig digitsAuthConfig = digitsAuthConfigBuilder.build();
    assertEquals(true, digitsAuthConfig.isEmailRequired);
    assertEquals(TestConstants.THEME_ID, digitsAuthConfig.themeResId);
    assertEquals(TestConstants.PHONE, digitsAuthConfig.phoneNumber);
    assertEquals(callback, digitsAuthConfig.authCallback);
  }