@Test
	public void testSelectAll() throws Exception {
		DomainFolder f = rootFolder.createFolder("myFolder");
		f = f.createFolder("A");
		f = f.createFolder("B");
		f = f.createFolder("C");
		waitForTree();

		setSelectionPath(rootNode.getTreePath());
		DockingActionIf selectAction = getAction("Select All");
		performAction(selectAction, getTreeActionContext(), true);
		waitForTree();

		BreadthFirstIterator it = new BreadthFirstIterator(rootNode);
		while (it.hasNext()) {
			GTreeNode node = it.next();
			assertTrue(tree.isPathSelected(node.getTreePath()));
		}
	}
Tests for actions in the front end (Ghidra project window)
Ghidra/Features/Base/src/test.slow/java/ghidra/framework/main/datatree/FrontEndPluginActionsTest.java