### Question:
IdUtils { public static String getEdgeId(final JSIDMNDiagram diagram, final List<String> dmnElementIds, final String dmnElementId) { final String diagramName = lower(diagram.getName()); return getUniqueId("dmnedge", diagramName, dmnElementId, 1, dmnElementIds); }  static String getPrefixedId(final String prefixId,
                                       final String rawId); static String getRawId(final String prefixedId); static String getComposedId(final String... parts); static String getShapeId(final JSIDMNDiagram diagram,
                                    final List<String> dmnElementIds,
                                    final String dmnElementId); static String getEdgeId(final JSIDMNDiagram diagram,
                                   final List<String> dmnElementIds,
                                   final String dmnElementId); static String uniqueId();  }### Answer:
@Test public void testGetEdgeId() { final JSIDMNDiagram diagram = mock(JSIDMNDiagram.class); when(diagram.getName()).thenReturn("DRG"); assertEquals("dmnedge-drg-_1111-2222", getEdgeId(diagram, list(), "_1111-2222")); }
@Test public void testGetEdgeIdWhenDiagramNameIsNull() { final JSIDMNDiagram diagram = mock(JSIDMNDiagram.class); assertEquals("dmnedge-_1111-2222", getEdgeId(diagram, list(), "_1111-2222")); }