Avoid instrumenting synthetic methods

Coverage was being generated for synthetic methods, artificially
inflating the number of covered lines for some kotlin classes. This
change prevents probes from being inserting into them, duplicating the
logic use elsewhere to ensure that lambda implementations still have
probes, despite their synthetic flag.

README.md

@@ -8,7 +8,11 @@ Read all about it at http://pitest.org
 
 ## Releases
 
-## 1.11.0 (unreleased)
+## 1.11.1
+
+* #1156 Prevent synthetic lines being counted in coverage
+
+## 1.11.0
 
 * #1138 Do not mutate redundant fall through to default switch cases
 * #1150 New extension points

pitest/src/main/java/org/pitest/classinfo/SyntheticMethodFilter.java

@@ -0,0 +1,30 @@
+package org.pitest.classinfo;
+
+import org.objectweb.asm.Opcodes;
+import org.pitest.functional.F5;
+
+/**
+ * Filters out synthetic and bridge methods, but allows synthetic
+ * lambdas. This logic is duplicated in org.pitest.bytecode.analysis.MethodTree
+ * when identifying code lines.
+ */
+public enum SyntheticMethodFilter implements
+        F5<Integer, String, String, String, String[], Boolean> {
+
+    INSTANCE;
+
+    @Override
+    public Boolean apply(final Integer access, final String name,
+                         final String desc, final String signature, final String[] exceptions) {
+        return (!isSynthetic(access, name) && !isBridge(access));
+    }
+
+    private static boolean isSynthetic(final int access, String name) {
+        return (access & Opcodes.ACC_SYNTHETIC) != 0 && !name.startsWith("lambda$");
+    }
+
+    private static boolean isBridge(final Integer access) {
+        return (access & Opcodes.ACC_BRIDGE) != 0;
+    }
+
+}

pitest/src/main/java/org/pitest/coverage/CoverageClassVisitor.java

@@ -21,8 +21,8 @@
 import org.objectweb.asm.FieldVisitor;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
-import org.pitest.classinfo.BridgeMethodFilter;
 import org.pitest.classinfo.MethodFilteringAdapter;
+import org.pitest.classinfo.SyntheticMethodFilter;
 import org.pitest.coverage.analysis.CoverageAnalyser;
 import sun.pitest.CodeCoverageStore;
 
@@ -43,7 +43,7 @@ public class CoverageClassVisitor extends MethodFilteringAdapter {
   private boolean   isInterface;
 
   public CoverageClassVisitor(final int classId, final ClassWriter writer) {
-    super(writer, BridgeMethodFilter.INSTANCE);
+    super(writer, SyntheticMethodFilter.INSTANCE);
     this.classId = classId;
   }
 

pitest/src/test/java/org/pitest/coverage/CoverageTransformerTest.java

@@ -55,16 +55,14 @@ public void tearDown() {
   }
 
   @Test
-  public void shouldNotTransformClassesNotMatchingPredicate()
-      throws IllegalClassFormatException {
+  public void shouldNotTransformClassesNotMatchingPredicate() {
     final CoverageTransformer testee = new CoverageTransformer(
         False.<String> instance());
     assertNull(testee.transform(null, "anything", null, null, null));
   }
 
   @Test
-  public void shouldTransformClasseMatchingPredicate()
-      throws IllegalClassFormatException {
+  public void shouldTransformClasseMatchingPredicate() {
     final CoverageTransformer testee = new CoverageTransformer(
         s -> true);
     final byte[] bs = this.bytes.getBytes(String.class.getName()).get();
@@ -83,8 +81,7 @@ public void shouldGenerateValidClasses() throws IllegalClassFormatException {
     assertValidClass(Math.class);
   }
 
-  private void assertValidClass(final Class<?> clazz)
-      throws IllegalClassFormatException {
+  private void assertValidClass(final Class<?> clazz) {
     final byte[] bs = transform(clazz);
     // printClass(bs);
     final StringWriter sw = new StringWriter();
@@ -105,8 +102,7 @@ protected void printClass(final byte[] bs) {
         System.out)), ClassReader.EXPAND_FRAMES);
   }
 
-  private byte[] transform(final Class<?> clazz)
-      throws IllegalClassFormatException {
+  private byte[] transform(final Class<?> clazz) {
     final CoverageTransformer testee = new CoverageTransformer(
         s -> true);
     return testee.transform(this.loader, clazz.getName(), null,