rework record interceptor to filter based on a marker line number

pitest-entry/src/main/java/org/pitest/mutationtest/build/intercept/javafeatures/RecordFilter.java

@@ -1,9 +1,6 @@
 package org.pitest.mutationtest.build.intercept.javafeatures;
 
-import org.objectweb.asm.Type;
-import org.objectweb.asm.tree.AbstractInsnNode;
-import org.objectweb.asm.tree.InvokeDynamicInsnNode;
-import org.objectweb.asm.tree.RecordComponentNode;
+import org.objectweb.asm.tree.LineNumberNode;
 import org.pitest.bytecode.analysis.ClassTree;
 import org.pitest.bytecode.analysis.MethodTree;
 import org.pitest.mutationtest.build.InterceptorType;
@@ -12,11 +9,16 @@
 import org.pitest.mutationtest.engine.MutationDetails;
 
 import java.util.Collection;
-import java.util.Optional;
-import java.util.Set;
+import java.util.OptionalInt;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
+/**
+ * Simple filter for autogenerated methods in records (eg constructors and accessors).
+ *
+ * Relies on the compiler including the line number of the line on which the record is declared
+ * within the autogenerated methods.
+ */
 public class RecordFilter implements MutationInterceptor {
 
     private boolean isRecord;
@@ -33,6 +35,7 @@ public void begin(ClassTree clazz) {
         currentClass = clazz;
     }
 
+
     @Override
     public Collection<MutationDetails> intercept(Collection<MutationDetails> mutations, Mutater m) {
         if (isRecord) {
@@ -44,67 +47,39 @@ public Collection<MutationDetails> intercept(Collection<MutationDetails> mutatio
     }
 
     private Predicate<MutationDetails> makeMethodFilter(ClassTree currentClass) {
-        Set<String> accessorNames = currentClass.recordComponents().stream()
-                .map(this::toName)
-                .collect(Collectors.toSet());
-        return m -> !accessorNames.contains(m.getMethod()) && !isStandardMethod(accessorNames.size(), m);
-    }
-
-    private boolean isStandardMethod(int numberOfComponents, MutationDetails m) {
-        return isRecordInit(m, numberOfComponents)
-                || isRecordEquals(m)
-                || isRecordHashCode(m)
-                || isRecordToString(m);
-    }
-
-    private boolean isRecordInit(MutationDetails m, int numberOfComponents) {
-        // constructors with the same airty as the generated ones, but different
-        // types won't get mutated. They're probably rare enough that this doesn't matter.
-        int airty = Type.getArgumentTypes(m.getId().getLocation().getMethodDesc()).length;
-        return m.getMethod().equals("<init>") && airty == numberOfComponents;
-    }
-
-    private boolean isRecordEquals(MutationDetails m) {
-        return m.getId().getLocation().getMethodDesc().equals("(Ljava/lang/Object;)Z")
-                && m.getMethod().equals("equals")
-                && hasDynamicObjectMethodsCall(m);
+        int declarationLine = currentClass.methods().stream()
+                    .map(this::singleLineMethod)
+                    .filter(OptionalInt::isPresent)
+                    .mapToInt(OptionalInt::getAsInt)
+                    .min()
+                    .orElse(-1);
+
+        var avoid = currentClass.methods().stream()
+                .filter( m -> hasLine(m, declarationLine))
+                .map(MethodTree::asLocation)
+                                .collect(Collectors.toSet());
+
+        return m -> !avoid.contains(m.getId().getLocation());
     }
 
-    private boolean isRecordHashCode(MutationDetails m) {
-        return m.getId().getLocation().getMethodDesc().equals("()I")
-                && m.getMethod().equals("hashCode")
-                && hasDynamicObjectMethodsCall(m);
-    }
-
-    private boolean isRecordToString(MutationDetails m) {
-        return m.getId().getLocation().getMethodDesc().equals("()Ljava/lang/String;")
-                && m.getMethod().equals("toString")
-                && hasDynamicObjectMethodsCall(m);
-    }
-
-    private boolean hasDynamicObjectMethodsCall(MutationDetails mutation) {
-        // java/lang/runtime/ObjectMethods was added to support records and can be used as a marker
-        // for an auth generated equals method. It's not likely that a custom method would
-        // contain a dynamic call to it
-        Optional<MethodTree> method = currentClass.method(mutation.getId().getLocation());
-        return method.filter(m -> m.instructions().stream().anyMatch(this::isInvokeDynamicCallToObjectMethods))
-                .isPresent();
-    }
-
-    private boolean isInvokeDynamicCallToObjectMethods(AbstractInsnNode node) {
-        if (node instanceof InvokeDynamicInsnNode) {
-            InvokeDynamicInsnNode call = (InvokeDynamicInsnNode) node;
-            return call.bsm.getOwner().equals("java/lang/runtime/ObjectMethods")
-                && call.bsm.getName().equals("bootstrap");
+    // iff the method has only one line, return it
+    private OptionalInt singleLineMethod(MethodTree methodTree) {
+        var lines = methodTree.instructions().stream()
+                .filter(n -> n instanceof LineNumberNode)
+                .map(n -> ((LineNumberNode) n).line)
+                .collect(Collectors.toSet());
 
+        if (lines.size() == 1) {
+            return OptionalInt.of(lines.iterator().next());
         }
-        return false;
+        return OptionalInt.empty();
     }
 
-    private String toName(RecordComponentNode recordComponentNode) {
-       return recordComponentNode.name;
+    private boolean hasLine(MethodTree m, int declarationLine) {
+        return m.instructions().stream().anyMatch(n -> n instanceof LineNumberNode && ((LineNumberNode) n).line == declarationLine);
     }
 
+
     @Override
     public void end() {
         currentClass = null;

pitest-entry/src/test/java/org/pitest/mutationtest/build/intercept/javafeatures/RecordFilterTest.java

@@ -31,7 +31,7 @@ public void findsNoMutantsInPureRecord() {
     }
 
     @Test
-    public void findsMutantsInNormalClass() {
+    public void filtersNoMutantsFromNormalClass() {
         this.verifier.assertFiltersNoMutationsMatching(m -> true, NotARecord.class);
     }
 
@@ -64,6 +64,11 @@ public void mutatesCustomToStringMethods() {
                 "RecordWithCustomToString");
     }
 
+    @Test
+    public void mutatesCompactConstructor() {
+        this.verifier.assertFiltersNoMutationsMatching(inMethodCalled("<init>"), "RecordWithCompactConstructor");
+    }
+
     private Predicate<MutationDetails> removesSysOutCall() {
         return m -> m.getDescription().contains("PrintStream::println");
     }

samples/src/main/java/com/example/RecordWithCompactConstructor.java

@@ -0,0 +1,18 @@
+package com.example;
+
+public record RecordWithCompactConstructor(int quantity) {
+  public RecordWithCompactConstructor {
+    if (quantity <= 0) {
+      System.out.println("mutate me");
+      throw new IllegalArgumentException("quantity must be positive");
+    }
+  }
+
+  @Override
+  public int quantity() {
+    if (quantity > 100) {
+      return 100;
+    }
+    return quantity;
+  }
+}