void () { myFixture.addClass("package com.intellij.lang; public class LanguageExtensionPoint {}"); myFixture.testHighlighting("MyLanguageExtensionPoint.java", "MyLanguageExtensionPointInterface.java", "extensionPointWithKnownRequiredAttributeAndTag.xml"); IntentionAction intention = myFixture.findSingleIntention("Register extension"); myFixture.launchAction(intention); myFixture.checkResultByFile("extensionPointWithKnownRequiredAttributeAndTag.xml", "extensionPointWithKnownRequiredAttributeAndTag_after.xml", true); }