filter mutants in enum switch default block

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

@@ -2,6 +2,9 @@
 
 import org.objectweb.asm.tree.AbstractInsnNode;
 import org.objectweb.asm.tree.FieldInsnNode;
+import org.objectweb.asm.tree.LabelNode;
+import org.objectweb.asm.tree.LookupSwitchInsnNode;
+import org.objectweb.asm.tree.TableSwitchInsnNode;
 import org.pitest.bytecode.analysis.MethodTree;
 import org.pitest.mutationtest.build.intercept.Region;
 import org.pitest.mutationtest.build.intercept.RegionInterceptor;
@@ -13,16 +16,18 @@
 import org.pitest.sequence.Slot;
 import org.pitest.sequence.SlotWrite;
 
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
 import static org.pitest.bytecode.analysis.InstructionMatchers.anyInstruction;
+import static org.pitest.bytecode.analysis.InstructionMatchers.labelNode;
 import static org.pitest.bytecode.analysis.InstructionMatchers.methodCallNamed;
 import static org.pitest.bytecode.analysis.InstructionMatchers.notAnInstruction;
 import static org.pitest.bytecode.analysis.OpcodeMatchers.ALOAD;
+import static org.pitest.bytecode.analysis.OpcodeMatchers.ATHROW;
 import static org.pitest.bytecode.analysis.OpcodeMatchers.IALOAD;
-import static org.pitest.bytecode.analysis.OpcodeMatchers.LOOKUPSWITCH;
-import static org.pitest.bytecode.analysis.OpcodeMatchers.TABLESWITCH;
 import static org.pitest.sequence.Result.result;
 
 /**
@@ -43,14 +48,34 @@
 public class EnumSwitchFilter extends RegionInterceptor {
     static final Slot<AbstractInsnNode> START = Slot.create(AbstractInsnNode.class);
     static final Slot<AbstractInsnNode> END = Slot.create(AbstractInsnNode.class);
+    static final Slot<LabelNode> DEFAULT = Slot.create(LabelNode.class);
+    static final Slot<AbstractInsnNode> DEFAULT_END = Slot.create(AbstractInsnNode.class);
 
     static final SequenceMatcher<AbstractInsnNode> ENUM_SWITCH = QueryStart
             .any(AbstractInsnNode.class)
             .then(getStatic("$SwitchMap$").and(store(START.write())))
             .then(ALOAD)
             .then(methodCallNamed("ordinal"))
             .then(IALOAD.and(store(END.write())))
-            .then(LOOKUPSWITCH.or(TABLESWITCH))
+            .then(lookupSwitch().or(tableSwitch()))
+            .zeroOrMore(QueryStart.match(anyInstruction()))
+            .compile(QueryParams.params(AbstractInsnNode.class)
+                    .withIgnores(notAnInstruction())
+            );
+
+    // detects default handlers that look like autogenerated ones
+    static final SequenceMatcher<AbstractInsnNode> ENUM_SWITCH_DEFAULT = QueryStart
+            .any(AbstractInsnNode.class)
+            .then(getStatic("$SwitchMap$").and(store(START.write())))
+            .then(ALOAD)
+            .then(methodCallNamed("ordinal"))
+            .then(IALOAD.and(store(END.write())))
+            .then(lookupSwitch().or(tableSwitch()))
+            .zeroOrMore(QueryStart.match(anyInstruction()))
+            .then(labelNode(DEFAULT.read()))
+            .oneOrMore(QueryStart.match(anyInstruction()))
+            // this will also match if a custom handler has a throw, but hopefully that is rare
+            .then(ATHROW.and(store(DEFAULT_END.write())))
             .zeroOrMore(QueryStart.match(anyInstruction()))
             .compile(QueryParams.params(AbstractInsnNode.class)
                     .withIgnores(notAnInstruction())
@@ -65,12 +90,47 @@ private static Match<AbstractInsnNode> getStatic(String name) {
         };
     }
 
+    public static Match<AbstractInsnNode> lookupSwitch() {
+        return (c, t) -> {
+            if ( t instanceof LookupSwitchInsnNode) {
+                final LookupSwitchInsnNode call = (LookupSwitchInsnNode) t;
+                return result(true, c.store(DEFAULT.write(), call.dflt));
+            }
+            return result(false, c);
+        };
+    }
+
+    public static Match<AbstractInsnNode> tableSwitch() {
+        return (c, t) -> {
+            if ( t instanceof TableSwitchInsnNode) {
+                final TableSwitchInsnNode call = (TableSwitchInsnNode) t;
+                return result(true, c.store(DEFAULT.write(), call.dflt));
+            }
+            return result(false, c);
+        };
+    }
+
 
     protected List<Region> computeRegions(MethodTree method) {
         Context context = Context.start();
-        return ENUM_SWITCH.contextMatches(method.instructions(), context).stream()
+        var matches = ENUM_SWITCH.contextMatches(method.instructions(), context);
+        var body = matches.stream()
                 .map(c -> new Region(c.retrieve(START.read()).get(), c.retrieve(END.read()).get()))
                 .collect(Collectors.toList());
+        if (!body.isEmpty()) {
+            body.addAll(defaultHandler(method));
+            return body;
+        }
+
+        return Collections.emptyList();
+    }
+
+    private Collection<Region> defaultHandler(MethodTree method) {
+        Context context = Context.start();
+        var matches = ENUM_SWITCH_DEFAULT.contextMatches(method.instructions(), context);
+        return matches.stream()
+                .map(c -> new Region(c.retrieve(DEFAULT.read()).get(), c.retrieve(DEFAULT_END.read()).get()))
+                .collect(Collectors.toList());
     }
 
     private static Match<AbstractInsnNode> store(SlotWrite<AbstractInsnNode> slot) {

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

@@ -0,0 +1,7 @@
+package org.pitest.mutationtest.build.intercept.javafeatures;
+
+public class Canary {
+  public static void mutateThisCall() {
+
+  }
+}

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

@@ -6,7 +6,10 @@
 import org.pitest.verifier.interceptors.InterceptorVerifier;
 import org.pitest.verifier.interceptors.VerifierStart;
 
+import static org.pitest.bytecode.analysis.InstructionMatchers.methodCallNamed;
 import static org.pitest.bytecode.analysis.InstructionMatchers.methodCallTo;
+import static org.pitest.bytecode.analysis.InstructionMatchers.opCode;
+import static org.pitest.bytecode.analysis.OpcodeMatchers.ATHROW;
 import static org.pitest.bytecode.analysis.OpcodeMatchers.GETSTATIC;
 import static org.pitest.bytecode.analysis.OpcodeMatchers.LOOKUPSWITCH;
 import static org.pitest.bytecode.analysis.OpcodeMatchers.TABLESWITCH;
@@ -70,6 +73,27 @@ public void leavesLookupSwitchStatement() {
                 .noMutantsAreFiltered()
                 .verify();
     }
+
+    @Test
+    public void filtersMutantsInAutogeneratedDefaultHandler() {
+        v.usingResourceFolder("matching")
+                .forClass("ExhaustiveSwitch")
+                .forCodeMatching(ATHROW.asPredicate())
+                .mutantsAreGenerated()
+                .allMutantsAreFiltered()
+                .verify();
+
+    }
+
+    @Test
+    public void doesNotFilterHandRolledDefaultHandler() {
+        v.forClass(HasEnumTableSwitch.class)
+                .forCodeMatching(methodCallNamed("mutateThisCall").asPredicate())
+                .mutantsAreGenerated()
+                .noMutantsAreFiltered()
+                .verify();
+
+    }
 }
 
 class NormalSwitch {
@@ -99,6 +123,7 @@ int foo(Letters i) {
             case E:
                 return 2;
             default:
+                Canary.mutateThisCall();
                 return 0;
         }
     }

samples/src/main/java/com/example/matching/AnEnum.java

@@ -0,0 +1,5 @@
+package com.example.matching;
+
+public enum AnEnum {
+    ONE, TWO, THREE, FOUR
+}

samples/src/main/java/com/example/matching/ExhaustiveSwitch.java

@@ -0,0 +1,12 @@
+package com.example.matching;
+
+public class ExhaustiveSwitch {
+    private static String render(AnEnum e) {
+        return switch (e) {
+            case ONE -> "a";
+            case TWO -> "b";
+            case THREE -> "c";
+            case FOUR -> "d";
+        };
+    }
+}