ignore any constructor for exceptions in unused code check #426

Feuermagier · Feb 9, 2024 · d7010b6 · d7010b6
1 parent cd6ee80
commit d7010b6
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diff --git a/...e/src/main/java/de/firemage/autograder/core/check/unnecessary/UnusedCodeElementCheck.java b/...e/src/main/java/de/firemage/autograder/core/check/unnecessary/UnusedCodeElementCheck.java
@@ -31,6 +31,16 @@ private void checkUnused(StaticAnalysis staticAnalysis, CtNamedElement ctElement
             return;
         }
 
+        // ignore exception constructors and params in those constructors
+        CtConstructor<?> parentConstructor = ctElement.getParent(CtConstructor.class);
+        if (parentConstructor == null && ctElement instanceof CtConstructor<?> ctConstructor) {
+            parentConstructor = ctConstructor;
+        }
+
+        if (parentConstructor != null && SpoonUtil.isSubtypeOf(parentConstructor.getType(), java.lang.Throwable.class)) {
+            return;
+        }
+
         Predicate<CtElement> shouldVisit = element -> true;
         if (ctElement instanceof CtMethod<?> method) {
             // Methods are also unused if they are only referenced by themselves, i.e. they are called recursively

diff --git a/...e/src/test/java/de/firemage/autograder/core/check/general/TestUseDifferentVisibility.java b/...e/src/test/java/de/firemage/autograder/core/check/general/TestUseDifferentVisibility.java
@@ -538,4 +538,39 @@ public static void main(String[] args) {
 
         assertEquals(0, problems.size());
     }
+
+    @Test
+    void testConventionExceptionConstructor() throws LinterException, IOException {
+        ProblemIterator problems = this.checkIterator(StringSourceInfo.fromSourceStrings(
+            JavaVersion.JAVA_17,
+            Map.ofEntries(
+                Map.entry(
+                    "Main",
+                    """
+                    public class Main {
+                        public static void main(String[] args) {
+                            throw new MyException("abc123", 123);
+                        }
+                    }
+                    """
+                ),
+                Map.entry(
+                    "MyException",
+                    """
+                    public class MyException extends RuntimeException {
+                        public MyException() {}
+                        
+                        public MyException(String message) { super(message); }
+                        public MyException(String message, Throwable cause) { super(message, cause); }
+                        public MyException(Throwable cause) { super(cause); }
+                        
+                        public MyException(String message, int number) { super(message + number); } // this is used
+                    }
+                    """
+                )
+            )
+        ), PROBLEM_TYPES);
+
+        problems.assertExhausted();
+    }
 }
diff --git a/...c/test/java/de/firemage/autograder/core/check/unnecessary/TestUnusedCodeElementCheck.java b/...c/test/java/de/firemage/autograder/core/check/unnecessary/TestUnusedCodeElementCheck.java
@@ -667,4 +667,39 @@ void b(String parameterName) {}
 
         problems.assertExhausted();
     }
+
+    @Test
+    void testConventionExceptionConstructor() throws LinterException, IOException {
+        ProblemIterator problems = this.checkIterator(StringSourceInfo.fromSourceStrings(
+            JavaVersion.JAVA_17,
+            Map.ofEntries(
+                Map.entry(
+                    "Main",
+                    """
+                    public class Main {
+                        public static void main(String[] args) {
+                            throw new MyException("abc123", 123);
+                        }
+                    }
+                    """
+                ),
+                Map.entry(
+                    "MyException",
+                    """
+                    public class MyException extends RuntimeException {
+                        public MyException() {}
+                        
+                        public MyException(String message) { super(message); }
+                        public MyException(String message, Throwable cause) { super(message, cause); }
+                        public MyException(Throwable cause) { super(cause); }
+                        
+                        public MyException(String message, int number) { super(message + number); } // this is used
+                    }
+                    """
+                )
+            )
+        ), PROBLEM_TYPES);
+
+        problems.assertExhausted();
+    }
 }