Java: exclude abstract classes

Author: Jami Cogswell

java/ql/src/Likely Bugs/Frameworks/JUnit/JUnit5NonStaticInnerClassMissingNestedAnnotation.md

@@ -47,11 +47,18 @@ public class IntegerOperationTest {
 
 ## Implementation Notes
 
-The `@Nested` annotation does not apply to inner static classes, since the meaning of the annotation is to mark a class as "a *non-static* inner class containing `@Test` methods to be picked up by a build system". Therefore, this rule does not aim to target static inner test classes with a `@Nested` annotation, nor does it try to enforce such correct usage of `@Nested`. Therefore, any code that resembles below is not non-compliant to this rule.
+The `@Nested` annotation does not apply to inner static classes, since the meaning of the annotation is to mark a class as "a *non-static* inner class containing `@Test` methods to be picked up by a build system". It also does not apply to inner abstract classes since there is no use case for an `@Nested` annotation on an abstract class. Therefore, this rule does not aim to target static or abstract inner test classes with a `@Nested` annotation, nor does it try to enforce such correct usage of `@Nested`. Therefore, any code that resembles the below is not non-compliant to this rule.
 
 ``` java
 @Nested
-public static class Test6 { // COMPLIANT: Although invalid, this matter is out of the scope
+public static class TestStatic { // COMPLIANT: Although invalid, this matter is out of the scope
+  @Test
+  public void test() {
+  }
+}
+
+@Nested
+public abstract class TestAbstract { // COMPLIANT: Although invalid, this matter is out of the scope
   @Test
   public void test() {
   }

java/ql/src/Likely Bugs/Frameworks/JUnit/JUnit5NonStaticInnerClassMissingNestedAnnotation.ql

@@ -18,5 +18,7 @@ from JUnit5TestClass testClass
 where
   // `InnerClass` is a non-static, nested class.
   testClass instanceof InnerClass and
-  not testClass.hasAnnotation("org.junit.jupiter.api", "Nested")
+  not testClass.hasAnnotation("org.junit.jupiter.api", "Nested") and
+  // An abstract class should not have a `@Nested` annotation
+  not testClass.isAbstract()
 select testClass, "This JUnit5 inner test class lacks a '@Nested' annotation."

java/ql/test/query-tests/Likely Bugs/Frameworks/JUnit/AnnotationTest.java

@@ -44,4 +44,19 @@ public static class Test6 {
     public void test() {
     }
   }
+
+  public abstract class Test7 { // COMPLIANT: Abstract inner test classes don't need `@Nested`
+    @Test
+    public void test() {
+    }
+  }
+
+  // COMPLIANT: Invalid to use `@Nested` on an abstract class, but
+  // this matter is out of scope (see QHelp Implementation Notes)
+  @Nested
+  public abstract class Test8 {
+    @Test
+    public void test() {
+    }
+  }
 }