SingleFieldConstraintOperatorSelector { static boolean isValueMissing(final String constraintOperator, final String constraintValue) { return OperatorsOracle.isValueRequired(constraintOperator) && (constraintValue == null || constraintValue.isEmpty()); }  void configure(final SingleFieldConstraint constraint,
                          final Supplier<ConstraintValueEditor> constraintValueEditor,
                          final Function<SingleFieldConstraint, ConstraintValueEditor> constraintValueEditorProducer,
                          final FactPatternWidget parent,
                          final HorizontalPanel placeholderForDropdown,
                          final FlexTable constraintValueEditorWrapper,
                          final int constraintValueEditorRowIndex,
                          final int constraintValueEditorColumnIndex,
                          final AsyncPackageDataModelOracle oracle);  }
@Test public void testIsValueMissingOne() throws Exception { final String operator = "=="; final String value = ""; Assertions.assertThat(testedSelector.isValueMissing(operator, value)).isTrue(); }
@Test public void testIsValueMissingTwo() throws Exception { final String operator = "=="; final String value = "123"; Assertions.assertThat(testedSelector.isValueMissing(operator, value)).isFalse(); }
@Test public void testIsValueMissingThree() throws Exception { final String operator = "== null"; final String value = ""; Assertions.assertThat(testedSelector.isValueMissing(operator, value)).isFalse(); }
@Test public void testIsValueMissingFour() throws Exception { final String operator = "== null"; final String value = "123"; Assertions.assertThat(testedSelector.isValueMissing(operator, value)).isFalse(); }