IDEA-98682 (Class extends utility class does not ignore on empty child classes)

plugins/InspectionGadgets/src/com/siyeh/ig/psiutils/UtilityClassUtil.java

@@ -26,7 +26,7 @@ public class UtilityClassUtil {
     return isUtilityClass(aClass, true);
   }
 
-  public static boolean isUtilityClass(@NotNull PsiClass aClass, boolean checkExtends) {
+  public static boolean isUtilityClass(@NotNull PsiClass aClass, boolean fullCheck) {
     if (aClass.isInterface() || aClass.isEnum() || aClass.isAnnotationType()) {
       return false;
     }
@@ -34,7 +34,7 @@ public class UtilityClassUtil {
       return false;
     }
     final PsiReferenceList extendsList = aClass.getExtendsList();
-    if (checkExtends && extendsList != null && extendsList.getReferenceElements().length > 0) {
+    if (fullCheck && extendsList != null && extendsList.getReferenceElements().length > 0) {
       return false;
     }
     final PsiReferenceList implementsList = aClass.getImplementsList();
@@ -50,7 +50,7 @@ public class UtilityClassUtil {
     if (!allFieldsStatic(fields)) {
       return false;
     }
-    return staticMethodCount != 0 || fields.length != 0;
+    return (!fullCheck || staticMethodCount != 0) || fields.length != 0;
   }
 
   private static boolean allFieldsStatic(PsiField[] fields) {

plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/extends_utility_class/ExtendsUtilityClass.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2000-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.igtest.inheritance.extends_utility_class;
+
+public class ExtendsUtilityClass {
+// all members are static
+
+  public static void member() {}
+}
+class Extender extends ExtendsUtilityClass {}
+class Extender2 extends ExtendsUtilityClass {
+
+  public void nonStaticMethod() {}
+}

plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/extends_utility_class/expected.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>ExtendsUtilityClass.java</file>
+    <line>24</line>
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Class extends utility class</problem_class>
+    <description>Class &lt;code&gt;Extender2&lt;/code&gt; extends utility class 'ExtendsUtilityClass' #loc</description>
+  </problem>
+</problems>

plugins/InspectionGadgets/testsrc/com/siyeh/ig/inheritance/ExtendsUtilityClassInspectionTest.java

@@ -0,0 +1,12 @@
+package com.siyeh.ig.inheritance;
+
+import com.siyeh.ig.IGInspectionTestCase;
+
+public class ExtendsUtilityClassInspectionTest extends IGInspectionTestCase {
+
+  public void test() throws Exception {
+    final ExtendsUtilityClassInspection tool = new ExtendsUtilityClassInspection();
+    tool.ignoreUtilityClasses = true;
+    doTest("com/siyeh/igtest/inheritance/extends_utility_class", tool);
+  }
+}