### Question:
DetailViewModel implements ViewModel { public ReadOnlyStringProperty mobileLabelTextProperty() { return mobile.getReadOnlyProperty(); }  void initialize(); Command getEditCommand(); Command getRemoveCommand(); Command getEmailLinkCommand(); ReadOnlyStringProperty nameLabelTextProperty(); ReadOnlyStringProperty birthdayLabelTextProperty(); ReadOnlyStringProperty roleDepartmentLabelTextProperty(); ReadOnlyStringProperty emailLabelTextProperty(); ReadOnlyStringProperty phoneLabelTextProperty(); ReadOnlyStringProperty mobileLabelTextProperty(); ReadOnlyStringProperty cityPostalcodeLabelTextProperty(); ReadOnlyStringProperty streetLabelTextProperty(); ReadOnlyStringProperty countrySubdivisionLabelTextProperty(); static final String OPEN_EDIT_CONTACT_DIALOG; }### Answer:
@Test public void testMobileLabelText() { luke.setMobileNumber(null); obi.setMobileNumber("0123456789"); selectedContact.set(null); assertThat(viewModel.mobileLabelTextProperty()).hasValue(""); selectedContact.set(luke); assertThat(viewModel.mobileLabelTextProperty()).hasValue(""); selectedContact.set(obi); assertThat(viewModel.mobileLabelTextProperty()).hasValue("0123456789"); luke.setMobileNumber("+49 123 456 789"); selectedContact.set(luke); assertThat(viewModel.mobileLabelTextProperty()).hasValue("+49 123 456 789"); }