Test generation is enabled for interfaces via shortcut and menu actions #473 (#487)

Author: Vassiliy-Kudryashov

utbot-intellij/src/main/kotlin/org/utbot/intellij/plugin/ui/actions/GenerateTestsAction.kt

@@ -45,6 +45,7 @@ class GenerateTestsAction : AnAction() {
 
             if (psiElementHandler.isCreateTestActionAvailable(element)) {
                 val srcClass = psiElementHandler.containingClass(element) ?: return null
+                if (srcClass.isInterface) return null
                 val srcSourceRoot = srcClass.getSourceRoot() ?: return null
                 val srcMethods = TestIntegrationUtils.extractClassMethods(srcClass, false)
                 val focusedMethod = focusedMethodOrNull(element, srcMethods, psiElementHandler)