NPE during compilation of spec while testing a method with vararg parameter

[tomaszstec]

Issue description

The spock test fail to compile using gradle :test while testing method with vararg parameter. The compilation fails with the following error:

startup failed:
D:\DEV\spock-npe-bug\src\test\groovy\ABusinessClassTest.groovy: Unexpected error during compilation of spec 'ABusinessClassTest'. Maybe you have used invalid Spock syntax? Anyway, please file a bug report at http://issues.spockframework.org.

java.lang.NullPointerException
        at org.spockframework.util.AbstractExpressionConverter.convertAll(AbstractExpressionConverter.java:46)
        at org.spockframework.compiler.ConditionRewriter.visitArrayExpression(ConditionRewriter.java:391)
        at org.codehaus.groovy.ast.expr.ArrayExpression.visit(ArrayExpression.java:86)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.util.AbstractExpressionConverter.convertAll(AbstractExpressionConverter.java:48)
        at org.spockframework.compiler.ConditionRewriter.visitArgumentlistExpression(ConditionRewriter.java:125)
        at org.codehaus.groovy.ast.expr.ArgumentListExpression.visit(ArgumentListExpression.java:73)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.compiler.ConditionRewriter.visitMethodCallExpression(ConditionRewriter.java:93)
        at org.codehaus.groovy.ast.expr.MethodCallExpression.visit(MethodCallExpression.java:76)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.util.AbstractExpressionConverter.convertAll(AbstractExpressionConverter.java:48)
        at org.spockframework.compiler.ConditionRewriter.visitArgumentlistExpression(ConditionRewriter.java:125)
        at org.codehaus.groovy.ast.expr.ArgumentListExpression.visit(ArgumentListExpression.java:73)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.compiler.ConditionRewriter.visitMethodCallExpression(ConditionRewriter.java:93)
        at org.codehaus.groovy.ast.expr.MethodCallExpression.visit(MethodCallExpression.java:76)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.compiler.ConditionRewriter.visitBinaryExpression(ConditionRewriter.java:213)
        at org.codehaus.groovy.ast.expr.BinaryExpression.visit(BinaryExpression.java:58)
        at org.spockframework.util.AbstractExpressionConverter.convert(AbstractExpressionConverter.java:36)
        at org.spockframework.compiler.ConditionRewriter.rewriteOtherCondition(ConditionRewriter.java:657)
        at org.spockframework.compiler.ConditionRewriter.rewriteCondition(ConditionRewriter.java:600)
        at org.spockframework.compiler.ConditionRewriter.rewriteCondition(ConditionRewriter.java:581)
        at org.spockframework.compiler.ConditionRewriter.rewriteImplicitCondition(ConditionRewriter.java:68)
        at org.spockframework.compiler.DeepBlockRewriter.handleImplicitCondition(DeepBlockRewriter.java:194)
        at org.spockframework.compiler.DeepBlockRewriter.doVisitExpressionStatement(DeepBlockRewriter.java:70)
        at org.spockframework.compiler.AbstractDeepBlockRewriter.visitExpressionStatement(AbstractDeepBlockRewriter.java:89)
        at org.codehaus.groovy.ast.stmt.ExpressionStatement.visit(ExpressionStatement.java:40)
        at org.spockframework.compiler.StatementReplacingVisitorSupport.replace(StatementReplacingVisitorSupport.java:44)
        at org.spockframework.compiler.AbstractDeepBlockRewriter.visit(AbstractDeepBlockRewriter.java:73)
        at org.spockframework.compiler.DeepBlockRewriter.visit(DeepBlockRewriter.java:53)
        at org.spockframework.compiler.SpecRewriter.visitAnyBlock(SpecRewriter.java:325)
        at org.spockframework.compiler.model.ExpectBlock.accept(ExpectBlock.java:31)
        at org.spockframework.compiler.model.Method.accept(Method.java:70)
        at org.spockframework.compiler.model.Spec.accept(Spec.java:112)
        at org.spockframework.compiler.SpockTransform$Impl.processSpec(SpockTransform.java:78)
        at org.spockframework.compiler.SpockTransform$Impl.visit(SpockTransform.java:65)
        at org.spockframework.compiler.SpockTransform.visit(SpockTransform.java:48)
        at org.codehaus.groovy.transform.ASTTransformationVisitor.lambda$addPhaseOperationsForGlobalTransforms$4(ASTTransformationVisitor.java:337)
        at org.codehaus.groovy.control.CompilationUnit$ISourceUnitOperation.doPhaseOperation(CompilationUnit.java:880)
        at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:650)
        at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:627)
        at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:606)
        at org.gradle.api.internal.tasks.compile.ApiGroovyCompiler.execute(ApiGroovyCompiler.java:275)
        at org.gradle.api.internal.tasks.compile.ApiGroovyCompiler.execute(ApiGroovyCompiler.java:68)
        at org.gradle.api.internal.tasks.compile.GroovyCompilerFactory$DaemonSideCompiler.execute(GroovyCompilerFactory.java:87)
        at org.gradle.api.internal.tasks.compile.GroovyCompilerFactory$DaemonSideCompiler.execute(GroovyCompilerFactory.java:75)
        at org.gradle.api.internal.tasks.compile.daemon.AbstractDaemonCompiler$CompilerWorkAction.execute(AbstractDaemonCompiler.java:128)
        at org.gradle.workers.internal.DefaultWorkerServer.execute(DefaultWorkerServer.java:50)
        at org.gradle.workers.internal.AbstractClassLoaderWorker$1.create(AbstractClassLoaderWorker.java:47)
        at org.gradle.workers.internal.AbstractClassLoaderWorker$1.create(AbstractClassLoaderWorker.java:37)
        at org.gradle.internal.classloader.ClassLoaderUtils.executeInClassloader(ClassLoaderUtils.java:98)
        at org.gradle.workers.internal.AbstractClassLoaderWorker.executeInClassLoader(AbstractClassLoaderWorker.java:37)
        at org.gradle.workers.internal.IsolatedClassloaderWorker.execute(IsolatedClassloaderWorker.java:49)
        at org.gradle.workers.internal.WorkerDaemonServer.execute(WorkerDaemonServer.java:84)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.gradle.process.internal.worker.request.WorkerAction$1.call(WorkerAction.java:129)
        at org.gradle.process.internal.worker.child.WorkerLogEventListener.withWorkerLoggingProtocol(WorkerLogEventListener.java:41)
        at org.gradle.process.internal.worker.request.WorkerAction.run(WorkerAction.java:126)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
        at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
        at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
        at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
        at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:412)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
        at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
        at java.lang.Thread.run(Thread.java:748)

How to reproduce

1. Create simple gradle project with the configuration and groovy classes taken from the gist
2. Run the tests with
   ./gradlew :test

Link to a gist or similar

spock-npe-bug gist

Additional Environment information

Java/JDK

λ java -version
java version "1.8.0_221"
Java(TM) SE Runtime Environment (build 1.8.0_221-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode)

Groovy version

λ groovy -version
Groovy Version: 2.5.8 JVM: 1.8.0_221 Vendor: Oracle Corporation OS: Windows 10

Build tool version

Gradle

Tested with gradlew 6.1.1 as well as my standalone gradle 5.1.1 installation

λ ./gradlew -version

------------------------------------------------------------
Gradle 6.1.1
------------------------------------------------------------

Build time:   2020-01-24 22:30:24 UTC
Revision:     a8c3750babb99d1894378073499d6716a1a1fa5d

Kotlin:       1.3.61
Groovy:       2.5.8
Ant:          Apache Ant(TM) version 1.10.7 compiled on September 1 2019
JVM:          1.8.0_221 (Oracle Corporation 25.221-b11)
OS:           Windows 10 10.0 amd64

λ gradle -version

------------------------------------------------------------
Gradle 5.1.1
------------------------------------------------------------

Build time:   2019-01-10 23:05:02 UTC
Revision:     3c9abb645fb83932c44e8610642393ad62116807

Kotlin DSL:   1.1.1
Kotlin:       1.3.11
Groovy:       2.5.4
Ant:          Apache Ant(TM) version 1.9.13 compiled on July 10 2018
JVM:          1.8.0_221 (Oracle Corporation 25.221-b11)
OS:           Windows 10 10.0 amd64

Operating System

Windows 10

Build-tool dependencies used

Gradle/Grails

dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.5.8'
    testCompile group: 'org.spockframework', name: 'spock-core', version: '2.0-M3-groovy-3.0'
}

[Vampire]

Without looking further, if those actually are your dependencies, you will get other problems too.
Either you have to use the groovy-2 variant with Groovy 2 or the groovy-3 variant with Groovy 3, you cannot mix them.

[Vampire]

Ah, despite your dependency declaration, the conflict resolution uses Groovy 3, otherwise it would not even be valid Groovy syntax in Groovy 2 where you cannot use array initializers like new Object[]{} but have to do [] as Object[] or actually new Object[0] in both Groovy in Java. While toArray( with array argument is a deprecated usage and should be avoided anyway since Java 6 or so. But I agree that with Groovy 3 where the syntax is valid, there should not be an NPE in Spock code. :-)

[tomaszstec]

Ah, that was the problem 👍 . I changed the dependency with:

testCompile group: 'org.spockframework', name: 'spock-core', version: '2.0-M2-groovy-2.5'

and replaced the line:

ABusinessClass.aMethodWithVararg([].toArray(new Object[]{})) == []

with

ABusinessClass.aMethodWithVararg([].toArray(new Object[0])) == []

and it works.

Big thanks !!!

[Vampire]

Please do not close this issue, as I said, this is still a bug in the Groovy 3 variant

[Vampire]

Besides that you can also simply do ABusinessClass.aMethodWithVararg() == [], there is no need to provide an array explicitly.
Or you can do ABusinessClass.aMethodWithVararg([] as Object[]) == [].

[Vampire]

This is enough for reproduction actually:

class Foo extends Specification {
    def foo() {
        expect:
        new Object[]{}
    }
}

[tomaszstec]

Sorry for closing the issue. I don't know the conventions. I see that you opened the corresponding ticket so I assueme it all right. Thanks for the help. Good day!

[Vampire]

If you don't mind, please reopen.
I don't have permissions to re-open or close tickets.
As long as the pr is not fixed, this should stay open as the bug still exists, even if you have a work-around.

[tomaszstec]

Ok, no problem. Reopened.