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From Andres Almiray <>
Subject Updates on JaCoCo support
Date Tue, 14 Aug 2018 20:42:52 GMT
Hello everyone,

I've spent a couple of hours with JaCoCo team members at the Hackergarten
Bern this evening.
The goal of the session was to get started with an integration test for the
@Generated feature
added in Groovy 2.5.0.

You can see the outcome at

The good news is that Groovy applies @Generated on constructors added by
@Cannonical as well
as methods defined by the GroovyObject interface. The bad news is that the
test still fails
because the expectation is that *every* method generated by the compiler
that does not map
to a particular source line *should* be annotated with @Generated. The
following source

// This annotation generates the following
// - a constructor that takes an int as argument
// - a suitable implementation of toString()
// - a suitable implementation of hashCode()
// - a suitable implementation of equals(Object)
// - a public method named canEqual(Object)
// - a getter & setter for the valRead property
class GroovyDataClassTarget { // assertFullyCovered()

    int valRead // assertNotCovered()

    static void main(String[] args) {
        new GroovyDataClassTarget() // assertFullyCovered()

Generates bytecode equivalent to (decompiled with IntelliJ)

// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)

package org.jacoco.core.test.validation.groovy.targets;

import groovy.lang.GroovyObject;
import groovy.lang.MetaClass;
import groovy.transform.EqualsAndHashCode;
import groovy.transform.Generated;
import groovy.transform.ToString;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.codehaus.groovy.runtime.ScriptBytecodeAdapter;
import org.codehaus.groovy.runtime.callsite.CallSite;
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;
import org.codehaus.groovy.runtime.typehandling.ShortTypeHandling;
import org.codehaus.groovy.util.HashCodeHelper;

public class GroovyDataClassTarget implements GroovyObject {
    private int valRead;

    public GroovyDataClassTarget(int valRead) {
        CallSite[] var2 = $getCallSiteArray();
        MetaClass var3 = this.$getStaticMetaClass();
        this.metaClass = var3;
        this.valRead = DefaultTypeTransformation.intUnbox(valRead);

    public GroovyDataClassTarget() {
        CallSite[] var1 = $getCallSiteArray();

    public static void main(String... args) {
        CallSite[] var1 = $getCallSiteArray();

    public String toString() {
        CallSite[] var1 = $getCallSiteArray();
        Object _result = var1[1].callConstructor(StringBuilder.class);
        Object $toStringFirst = Boolean.TRUE;
        if (DefaultTypeTransformation.booleanUnbox($toStringFirst)) {
            Boolean var4 = Boolean.FALSE;
        } else {
            var1[3].call(_result, ", ");

        var1[4].call(_result, var1[5].callStatic(InvokerHelper.class,
        var1[7].call(_result, ")");

    public int hashCode() {
        CallSite[] var1 = $getCallSiteArray();
        Object _result = var1[9].callStatic(HashCodeHelper.class);
this))) {
            Object var3 = var1[12].callStatic(HashCodeHelper.class,
_result, var1[13].callCurrent(this));
            _result = var3;

        return DefaultTypeTransformation.intUnbox(_result);

    public boolean canEqual(Object other) {
        CallSite[] var2 = $getCallSiteArray();
        return other instanceof GroovyDataClassTarget;

    public boolean equals(Object other) {
        CallSite[] var2 = $getCallSiteArray();
        if (ScriptBytecodeAdapter.compareEqual(other, (Object)null)) {
            return false;
        } else if
(DefaultTypeTransformation.booleanUnbox(var2[14].callCurrent(this, other)))
            return true;
        } else if (!(other instanceof GroovyDataClassTarget)) {
            return false;
        } else {
            GroovyDataClassTarget otherTyped = (GroovyDataClassTarget)other;
(!DefaultTypeTransformation.booleanUnbox(var2[15].call(otherTyped, this))) {
                return false;
            } else {

    public int getValRead() {
        return this.valRead;

    public void setValRead(int var1) {
        this.valRead = var1;

We can appreciate that the methods added by @ToString, @EqualsAndHashcode,
and the property getter/setter are not
annotated with @Generated, which will prompt JaCoCo to mark them as not
covered. The rationale from the JaCoCo team
is that these methods should be annotated as the compiler is "trusted",
only those methods explicitly added to the
source should be covered.

Thus, here comes the call to action and the reason why I wanted to start
this conversation in the first place:
 - modify the Groovy compiler to add @Generated on property getters and
 - modify core AST xforms to add @Generated where it makes sense.

Related to the original @Generated issue (as commented by Evgeny at fields
do not have line numbers, would be good to have them.

What do you think?


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those who don't.
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