@Test
	public void testShowDropDownOnTextEntry() {

		JWindow matchingWindow = textField.getActiveMatchingWindow();

		// the window needs to be null initially because it must be properly parented when it is
		// created
		assertNull(
			"The completion window has been created before any completion work " + "has began.",
			matchingWindow);

		// insert some text and make sure the window is created
		typeText("d", true);

		// get the contents of the window and make sure that they are updated
		JList<String> jList = textField.getJList();
		int size = jList.getModel().getSize();

		// this will produce 'd2'
		typeText("2", true);

		assertNotEquals(
			"The number of matching items in the list did not change after typing more " + "text.",
			size, jList.getModel().getSize());
	}
This test achieves partial coverage of {@link DropDownTextField}.  Further coverage is
provided by {@link DropDownSelectionTextFieldTest}, as that test enables item selection 
in the widget being tested.
Ghidra/Framework/Docking/src/test/java/docking/widgets/DropDownTextFieldTest.java