### Question:
ExpressionGridCacheImpl extends AbstractCanvasControl<AbstractCanvas> implements ExpressionGridCache { @Override public void removeExpressionGrid(final String nodeUUID) { cache.remove(nodeUUID); } ExpressionGridCacheImpl(); @Override Optional<BaseExpressionGrid<? extends Expression, ? extends GridData, ? extends BaseUIModelMapper>> getExpressionGrid(final String nodeUUID); @Override void putExpressionGrid(final String nodeUUID,
                                  final Optional<BaseExpressionGrid<? extends Expression, ? extends GridData, ? extends BaseUIModelMapper>> gridWidget); @Override void removeExpressionGrid(final String nodeUUID);  }### Answer:
@Test public void testRemoveExpressionGrid() { final Map<String, Optional<BaseExpressionGrid<? extends Expression, ? extends GridData, ? extends BaseUIModelMapper>>> content = cache.getContent(); when(editor.isCacheable()).thenReturn(true); cache.putExpressionGrid(UUID, Optional.of(editor)); cache.removeExpressionGrid(""); assertThat(content).isNotEmpty(); assertThat(content.size()).isEqualTo(1); assertThat(content.containsKey(UUID)).isTrue(); assertThat(content.get(UUID)).isEqualTo(Optional.of(editor)); cache.removeExpressionGrid(UUID); assertThat(content).isEmpty(); }