private static void groupByValues(
      @NotNull Collection<PsiElement> leaves,
      @NotNull SliceRootNode oldRoot,
      @NotNull Map<SliceNode, Collection<PsiElement>> map) {
    assert oldRoot.myCachedChildren.size() == 1;
    SliceRootNode root = createTreeGroupedByValues(leaves, oldRoot, map);

    SliceNode oldRootStart = oldRoot.myCachedChildren.get(0);
    SliceUsage rootUsage = oldRootStart.getValue();
    String description =
        SliceManager.getElementDescription(null, rootUsage.getElement(), " (grouped by value)");
    SliceManager.getInstance(root.getProject()).createToolWindow(true, root, true, description);
  }
  public void testGroupByValuesCorrectLeaves() throws Exception {
    SliceTreeStructure treeStructure = configureTree("DuplicateLeaves");
    SliceRootNode root = (SliceRootNode) treeStructure.getRootElement();
    Map<SliceNode, Collection<PsiElement>> map = SliceLeafAnalyzer.createMap();
    Collection<PsiElement> leaves = SliceLeafAnalyzer.calcLeafExpressions(root, treeStructure, map);
    assertNotNull(leaves);
    assertEquals(1, leaves.size());
    PsiElement leaf = leaves.iterator().next();
    assertTrue(leaf instanceof PsiLiteralExpression);
    assertEquals("\"oo\"", leaf.getText());

    SliceRootNode newRoot = SliceLeafAnalyzer.createTreeGroupedByValues(leaves, root, map);
    Collection<? extends AbstractTreeNode> children = newRoot.getChildren();
    assertEquals(1, children.size());
    SliceNode child = (SliceNode) children.iterator().next();
    assertTrue(child instanceof SliceLeafValueRootNode);

    children = child.getChildren();
    assertEquals(1, children.size());
    child = (SliceNode) children.iterator().next();
    assertTrue(child.getValue().getElement() instanceof PsiField);

    children = child.getChildren();
    assertEquals(1, children.size());
    child = (SliceNode) children.iterator().next();
    assertTrue(child.getValue().getElement() instanceof PsiReferenceExpression);

    children = child.getChildren();
    assertEquals(1, children.size());
    child = (SliceNode) children.iterator().next();
    assertTrue(child.getValue().getElement() instanceof PsiReferenceExpression);

    children = child.getChildren();
    assertEquals(1, children.size());
    child = (SliceNode) children.iterator().next();
    assertTrue(child.getValue().getElement() instanceof PsiLiteralExpression);
    assertEquals(child.getValue().getElement(), leaf);
  }