Bug 11863 Update Test Suite action does not allow to remove
What the action actually does is RECREATE the test suite based on the selection in the dialog. I do an update on a test suite which contains X. It is no clear that if I only select Y in the dialog that I'll end up with X being removed. Normally "Update" shows the content of the existing stuff (dir, zip) and allows to modify this. I think renaming the action (and the dialog) to Recreate Test Suite would solve the problem.
org.eclipse.jdt.junit/src/org/eclipse/jdt/junit/wizards/NewTestCaseCreationWizardPage.java
IType type= null;
		try {
			SelectionDialog dialog= JavaUI.createTypeDialog(getShell(), getWizard().getContainer(), scope, IJavaElementSearchConstants.CONSIDER_CLASSES, false, null);
			dialog.setTitle(Messages.getString("NewTestClassWizPage.class_to_test.dialog.title")); 
			dialog.setMessage(Messages.getString("NewTestClassWizPage.class_to_test.dialog.message")); 
			dialog.open();
			if (dialog.getReturnCode() != SelectionDialog.OK)
				return type;
			else {
				Object[] resultArray= dialog.getResult();
				type= (IType) resultArray[0];
			}
		} catch (JavaModelException e) {
			JUnitPlugin.log(e);
		}
		return type;
	}
	protected IStatus classToTestClassChanged() {
		fClassToTestButton.setEnabled(getPackageFragmentRoot() != null);
		IStatus status= validateClassToTest();
		return status;
	}
	/**
	 * Gets the content of the class to test text field.
	 */
	public String getClassToTestText() {
		return fClassToTestText.getText();
	}