### Question:
AlphaNumeric implements Validation { @Override public String getErrorMessage(final Context context) { return context.getString(R.string.formvalidations_not_alphanumeric); } private  AlphaNumeric(); static AlphaNumeric build(); @Override String getErrorMessage(final Context context); @Override boolean isValid(final String text);  }### Answer:
@Test public void testGetErrorMessage() throws Exception { final String errorMessage = mAlphaNumeric.getErrorMessage(mActivity); assertNotNull(errorMessage); }