Is this legal in Groovy?
class RequestContext {
def static requestContext
def static setRequestContext(rc) {
requestContext = rc
}
}
Given the above I expect the following to fail at compile time using the groovy-eclipse-compiler:
RequestContext.setRequestContext()
Yet this passes and I'm trying to get this to fail at mvn compile time.
It can't fail at compile time, because you might add that method dynamically at runtime via the metaclass, ie:
class Test {
}
Test.metaClass.static.woo = { -> println "yay" }
Test.woo() // prints 'yay'
To fail at compile time, you'd need to annotate the calling class with #CompileStatic or #TypeChecked
Related
I stumbled across this when updating a large app from groovy 2 to 3 (and also to corresponding newer spock and geb versions).
This code behaves strange and also a different kind of strange in groovy 2 versus groovy 4.
I think we are running without "indy" here. I guess because all the transitive dependencies of our large app bring in specific groovy jars without indy. I should probably goe through them carefully and adapt our gradle build so that only "indy" versions of all jars are picked.
class A {
def foo() {
bar('hello')
beep(Optional.of('hello'))
}
protected void bar(String value) { println 'A.bar' }
protected void beep(Optional<String> value) { println 'A.beep' }
}
class B extends A {
protected void bar(String value) { println 'B.bar' }
protected void beep(Optional<String> value) { println 'B.beep' }
}
class C extends B implements GroovyInterceptable {
def invokeMethod(String name, Object args) {
super."$name"(*args)
}
}
static void main(String[] args) {
new C().foo()
println '---'
C c = new C()
c.bar('hello')
c.beep(Optional.of('hello'))
}
Output for groovy 2.5.15:
B.bar
A.beep
---
A.bar
A.beep
Output for groovy 4.0.0:
A.bar
A.beep
---
A.bar
A.beep
What I would have expected:
B.bar
B.beep
---
B.bar
B.beep
What's going on here? Bug or some strange, but expected corner case?
Where is the difference in behavior in between groovy 2 and 4 documented?
In our real app there was a difference already in between groovy 2 and 3 but I have been unable so far to create example code for that.
Is there a way to call the original method inside of invokeMethod? (Can't find anything in the docs, which are very sparse btw.)
I get your 3.0.9 output for Groovy 2.5.16, 3.0.10 and 4.0.1 -- indy enabled for all three.
Your implementation of invokeMethod relies on the behavior of ScriptBytecodeAdapter#invokeMethodOnSuperN which is what is behind super."$name"(*args). When handling "bar" message, the meta-method index has B.bar(java.lang.String) for "this" and B.super$2$bar(java.lang.String) for "super". super$2$bar is a meta-object protocol (MOP) method that provides the necessary INVOKESPECIAL instruction to reach A#bar(java.lang.String).
If you want the output of all calls to be from B then you can use this."$name"(*args) instead. In your specific case, there is no need to implement C as GroovyInterceptable and to try and route "foo", "bar" and "beep" yourself.
You can make your code produce the expected output by making the B class compiled statically:
import groovy.transform.CompileStatic
class A {
def foo() {
bar('hello')
beep(Optional.of('hello'))
}
protected void bar(String value) { println 'A.bar' }
protected void beep(Optional<String> value) { println 'A.beep' }
}
#CompileStatic
class B extends A {
protected void bar(String value) { println 'B.bar' }
protected void beep(Optional<String> value) { println 'B.beep' }
}
class C extends B implements GroovyInterceptable {
def invokeMethod(String name, Object args) {
super."$name"(*args)
}
}
static void main(String[] args) {
new C().foo()
println '---'
C c = new C()
c.bar('hello')
c.beep(Optional.of('hello'))
}
Output:
B.bar
B.beep
---
B.bar
B.beep
As it was mentioned by emilies in his answer, in the MOP use case scenario something like this happens:
c.bar('Hello')
invokeMethod('bar', ['Hello'] as Object[])
super."bar"(['Hello'] as Object[])
This super."bar"(['Hello'] as Object[]) is represented by B.super$2$bar(java.lang.String) method object which forces A.bar(java.lang.String) to be invoked right in the next call frame.
However, if you make the B class to be compiled statically, the method that is found to satisfy the super."bar"(['Hello'] as Object[]) expression, in that case, is B.bar(java.lang.String), and thus it gets invoked directly.
Regarding the differences between Groovy 2.5 and Groovy >=3.0, it looks like you have encountered a compiler bug. The bar('hello') inside the A.foo() method ignores the MOP and goes directly to this.bar(java.lang.String) which in this case is B.bar(java.lang.String).
It looks like it happens for the java.lang.String type (didn't check other types). However, when the type is java.util.Optional, then a call like beep(Optional.of('Hello')) inside the A.foo() method goes through the MOP and thus it discovers B.super$2$beep(java.util.Optional) method to be invoked:
I put this in my Spock test:
GroovyMock( File, global: true)
File.createNewFile() >> null
... which I realise is unorthodox/silly/curious: createNewFile is a non-static method.
The code involved is like this:
if( indexInfoFile.createNewFile() ) {
... it turns out from my experiements that mocking createNewFile like this always returns false, even if you try putting a block in the mock:
GroovyMock( File, global: true)
File.createNewFile() >> {
log.info( 'Hello mum!')
}
... the log message is not printed but createNewFile again returns false.
This is actually what I wanted (i.e. to mock a false return from createNewFile).
Is this intentional, documented behaviour?
PS Caveat: from my experience/experiments today, there is no doubt that this mock method does replace all occurrences of an invocation of this method, on any File instance. However, it appears also to have some alarming side-effects too: for example, a directory I created in my given block before the 2 GroovyMock lines is found NOT to exist afterwards, still in the given block, when I went
myDirPath.toFile().exists()
... I assume this is because toFile involves an invocation of createNewFile...
As documented, Groovy mocks only have additional "magic" when used with Groovy classes, but I assume that you are trying to mock java.io.File, which is a Java JRE class. Thus, the Groovy mock will behave like a normal Spock mock. So I don't know why you want to use the Groovy mock in the first place - maybe because you want to use the global: true feature in order to avoid refactoring for testability in your application class.
As you do not show us an MCVE, I have no way of knowing whether indexInfoFile can be injected into your class/method under test or if it is a dependency created inside the method. In the latter case you need to refactor, it is as simple as that. Dependencies should be injectable, period.
As for your code snippets, there are a few things wrong with them:
Method File.createNewFile() returns boolean, so it does not make any sense to stub it to return null.
When creating a mock, all methods will automatically return false, null or 0, depending on their return type. So there is no need to stub the result for createNewFile() in the first place if you want it to return false because it already does.
You cannot stub an instance method by trying to override it like it was a static method. It makes no sense. Please learn Spock syntax first.
Now, assuming your class under test looks like this (already prepared or refactored for dependency injection via method argument, constructor argument or setter)...
package de.scrum_master.stackoverflow.q59842227;
import java.io.File;
import java.io.IOException;
import java.util.Random;
public class FileCreator {
private static final Random RANDOM = new Random();
public boolean createIndexInfoFile(File indexInfoFile) throws IOException {
if (indexInfoFile.createNewFile()) {
System.out.println("File \"" + indexInfoFile + "\" created");
return true;
}
System.out.println("File \"" + indexInfoFile + "\" NOT created");
return false;
}
public static void main(String[] args) throws IOException {
new FileCreator().createIndexInfoFile(
new File("_abc_" + RANDOM.nextInt(10000) + ".txt")
);
}
}
... then you can test it like this:
package de.scrum_master.stackoverflow.q59842227
import spock.lang.Specification
class FileCreatorTest extends Specification {
def "index info file created"() {
given:
File file = Mock() {
createNewFile() >> true
}
expect:
new FileCreator().createIndexInfoFile(file)
}
def "no index info file created"() {
given:
File file = Mock()
expect:
!new FileCreator().createIndexInfoFile(file)
}
}
See? There is no need for global or Groovy mocks, normal mocks will do just fine. But you need to make your code testable instead of using fancy tricks.
I'm running into a problem with GroovyScriptEngine - it seems not to be able to work with inner classes. Anyone know whether there's some limitation in GroovyScriptEngine or a workaround?
I have a directory with these two files:
// MyClass.groovy
public class MyClass {
MyOuter m1;
MyOuter.MyInner m2;
}
and
// MyOuter.groovy
public class MyOuter {
public static class MyInner {}
}
I have a following test class:
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import groovy.util.GroovyScriptEngine;
public class TestGroovyScriptEngine {
public static void main(String[] args) throws MalformedURLException, ClassNotFoundException {
final File myGroovySourceDir = new File("C:/MyGroovySourceDir");
final URL[] urls = { myGroovySourceDir.toURL() };
GroovyScriptEngine groovyScriptEngine = new GroovyScriptEngine(urls,
Thread.currentThread().getContextClassLoader());
Class<?> clazz = groovyScriptEngine.getGroovyClassLoader().loadClass("MyClass");
}
}
When I run it I get the following compilation error:
Exception in thread "main" org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
C:\MyGroovySourceDir\MyClass.groovy: 3: unable to resolve class MyOuter.MyInner
# line 3, column 2.
MyOuter.MyInner m2;
^
1 error
at org.codehaus.groovy.control.ErrorCollector.failIfErrors(ErrorCollector.java:311)
at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:983)
at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:633)
at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:582)
at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:354)
at groovy.lang.GroovyClassLoader.access$300(GroovyClassLoader.java:87)
at groovy.lang.GroovyClassLoader$5.provide(GroovyClassLoader.java:323)
at groovy.lang.GroovyClassLoader$5.provide(GroovyClassLoader.java:320)
at org.codehaus.groovy.runtime.memoize.ConcurrentCommonCache.getAndPut(ConcurrentCommonCache.java:147)
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:318)
at groovy.util.GroovyScriptEngine$ScriptClassLoader.doParseClass(GroovyScriptEngine.java:248)
at groovy.util.GroovyScriptEngine$ScriptClassLoader.parseClass(GroovyScriptEngine.java:235)
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:307)
at groovy.lang.GroovyClassLoader.recompile(GroovyClassLoader.java:811)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:767)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:836)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:824)
I would have expected a "clean compile", but the inner class seems to be causing problems.
My groovy classes compile fine at the command line using groovyc, or in Eclipse.
You have faced an edge case here. To clarify what happens let's define the initial conditions:
you have a Java (or Groovy) class that gets executed inside JVM
you have two Groovy classes that get loaded outside of the JVM
The problem you have described does not exist if you put these two Groovy classes inside the same path you execute your Java class from - in this case IDE takes care to compile these Groovy classes and put them to the classpath of a JVM that gets started to run your Java test class.
But this is not your case and you are trying to load these two Groovy classes outside the running JVM using GroovyClassLoader (which extends URLClassLoader btw). I will try to explain in the simplest possible words what happened that adding field of type MyOuter does not throw any compilation error, but MyOuter.MyInner does.
When you execute:
Class<?> clazz = groovyScriptEngine.getGroovyClassLoader().loadClass("MyClass");
Groovy class loader goes to script file lookup part, because it was not able to find MyClass in the current classpath. This is the part responsible for it:
// at this point the loading from a parent loader failed
// and we want to recompile if needed.
if (lookupScriptFiles) {
// try groovy file
try {
// check if recompilation already happened.
final Class classCacheEntry = getClassCacheEntry(name);
if (classCacheEntry != cls) return classCacheEntry;
URL source = resourceLoader.loadGroovySource(name);
// if recompilation fails, we want cls==null
Class oldClass = cls;
cls = null;
cls = recompile(source, name, oldClass);
} catch (IOException ioe) {
last = new ClassNotFoundException("IOException while opening groovy source: " + name, ioe);
} finally {
if (cls == null) {
removeClassCacheEntry(name);
} else {
setClassCacheEntry(cls);
}
}
}
Source: src/main/groovy/lang/GroovyClassLoader.java#L733-L753
Here URL source = resourceLoader.loadGroovySource(name); it loads the full file URL to the source file and here cls = recompile(source, name, oldClass); it executes class compilation.
There are several phases involved in Groovy class compilation. One of them is Phase.SEMANTIC_ANALYSIS which analyses class fields and their types for instance. At this point ClassCodeVisitorSupport executes visitClass(ClassNode node) for MyClass class and following line
node.visitContents(this);
starts class contents processing. If we take a look at the source code of this method:
public void visitContents(GroovyClassVisitor visitor) {
// now let's visit the contents of the class
for (PropertyNode pn : getProperties()) {
visitor.visitProperty(pn);
}
for (FieldNode fn : getFields()) {
visitor.visitField(fn);
}
for (ConstructorNode cn : getDeclaredConstructors()) {
visitor.visitConstructor(cn);
}
for (MethodNode mn : getMethods()) {
visitor.visitMethod(mn);
}
}
Source: src/main/org/codehaus/groovy/ast/ClassNode.java#L1066-L108
we will see that it analyses and process class properties, fields, constructors and methods. At this phase it resolves all types defined for these elements. It sees that there are two properties m1 and m2 with types MyOuter and MyOuter.MyInner accordingly, and it executes visitor.visitProperty(pn); for them. This method executes the one we are looking for - resolve()
private boolean resolve(ClassNode type, boolean testModuleImports, boolean testDefaultImports, boolean testStaticInnerClasses) {
resolveGenericsTypes(type.getGenericsTypes());
if (type.isResolved() || type.isPrimaryClassNode()) return true;
if (type.isArray()) {
ClassNode element = type.getComponentType();
boolean resolved = resolve(element, testModuleImports, testDefaultImports, testStaticInnerClasses);
if (resolved) {
ClassNode cn = element.makeArray();
type.setRedirect(cn);
}
return resolved;
}
// test if vanilla name is current class name
if (currentClass == type) return true;
String typeName = type.getName();
if (genericParameterNames.get(typeName) != null) {
GenericsType gt = genericParameterNames.get(typeName);
type.setRedirect(gt.getType());
type.setGenericsTypes(new GenericsType[]{ gt });
type.setGenericsPlaceHolder(true);
return true;
}
if (currentClass.getNameWithoutPackage().equals(typeName)) {
type.setRedirect(currentClass);
return true;
}
return resolveNestedClass(type) ||
resolveFromModule(type, testModuleImports) ||
resolveFromCompileUnit(type) ||
resolveFromDefaultImports(type, testDefaultImports) ||
resolveFromStaticInnerClasses(type, testStaticInnerClasses) ||
resolveToOuter(type);
}
Source: src/main/org/codehaus/groovy/control/ResolveVisitor.java#L343-L378
This method gets executed for both MyOuter and MyOuter.MyInner classes. It is worth mentioning that class resolving mechanism only checks if given class is available in the classpath and it does not load or parse any classes. That is why MyOuter gets recognized when this method reaches resolveToOuter(type). If we take a quick look at its source code we will understand why it works for this class:
private boolean resolveToOuter(ClassNode type) {
String name = type.getName();
// We do not need to check instances of LowerCaseClass
// to be a Class, because unless there was an import for
// for this we do not lookup these cases. This was a decision
// made on the mailing list. To ensure we will not visit this
// method again we set a NO_CLASS for this name
if (type instanceof LowerCaseClass) {
classNodeResolver.cacheClass(name, ClassNodeResolver.NO_CLASS);
return false;
}
if (currentClass.getModule().hasPackageName() && name.indexOf('.') == -1) return false;
LookupResult lr = null;
lr = classNodeResolver.resolveName(name, compilationUnit);
if (lr!=null) {
if (lr.isSourceUnit()) {
SourceUnit su = lr.getSourceUnit();
currentClass.getCompileUnit().addClassNodeToCompile(type, su);
} else {
type.setRedirect(lr.getClassNode());
}
return true;
}
return false;
}
Source: src/main/org/codehaus/groovy/control/ResolveVisitor.java#L725-L751
When Groovy class loader tries to resolve MyOuter type name it reaches
lr = classNodeResolver.resolveName(name, compilationUnit);
which locates script with a name MyOuter.groovy and it creates a SourceUnit object associated with this script file name. It is simply something like saying "OK, this class is not in my classpath at the moment, but there is a source file I can see that once compiled it will provide a valid type of name MyOuter". This is why it finally reaches:
currentClass.getCompileUnit().addClassNodeToCompile(type, su);
where currentClass is an object associated with MyClass type - it adds this source unit to MyClass compilation unit, so it gets compiled with the MyClass class. And this is the point where resolving
MyOuter m1
class property ends.
In the next step it picks MyOuter.MyInner m2 property and it tries to resolve its type. Keep in mind - MyOuter got resolved correctly, but it didn't get loaded to the classpath, so it's static inner class does not exist in any scope, yet. It goes through the same resolving strategies as MyOuter, but any of them works for MyOuter.MyInner class. And this is why ResolveVisitor.resolveOrFail() eventually throws this compilation exception.
Workaround
OK, so we know what happens, but is there anything we can do about it? Luckily, there is a workaround for this problem. You can run your program and load MyClass successfully only if you load MyOuter class to Groovy script engine first:
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import groovy.util.GroovyScriptEngine;
public class TestGroovyScriptEngine {
public static void main(String[] args) throws MalformedURLException, ClassNotFoundException {
final File myGroovySourceDir = new File("C:/MyGroovySourceDir");
final URL[] urls = { myGroovySourceDir.toURL() };
GroovyScriptEngine groovyScriptEngine = new GroovyScriptEngine(urls,
Thread.currentThread().getContextClassLoader());
groovyScriptEngine.getGroovyClassLoader().loadClass("MyOuter");
Class<?> clazz = groovyScriptEngine.getGroovyClassLoader().loadClass("MyClass");
}
}
Why does it work? Well, semantic analysis of MyOuter class does not cause any problems, because all types are known at this stage. This is why loading MyOuter class succeeds and it results in Groovy script engine instance knows what MyOuter and MyOuter.MyInner types are. So when you next load MyClass from the same Groovy script engine it will apply different resolving strategy - it will find both classes available to the current compilation unit and it wont have to resolve MyOuter class based on its Groovy script file.
Debugging
If you want to examine this use case better it is worth to run a debugger and see analyze what happens at the runtime. You can create a breakpoint at line 357 of ResolveVisitor.java file for instance, to see described scenario in action. Keep in mind one thing though - resolveFromDefaultImports(type, testDefaultImports) will try to lookup MyClass and MyOuter classes by applying default packages like java.util, java.io, groovy.lang etc. This resolve strategy kicks in before resolveToOuter(type) so you have to patiently jump through them. But it is worth it to see and get a better understanding about how things work. Hope it helps!
I want to write a groovy DSL with syntax:
returnValue when booleanCondition
I want to use compilation customizers to transform this expression to a typical if return statement using AST transformations.
For this script:
2 when 1 == 1
I get exception message:
MultipleCompilationErrorsException: startup failed:
Script1.groovy: 1: expecting EOF, found '1' # line 1, column 8.
I don't understand why my compilation customizer is not called at all?
I need it to be called before compilation so I can make it into a valid groovy code.
If the script contains valid groovy code, then my compilation customizer is called.
My code:
class MyDslTest {
public static void main(String[] args) {
String script = '''2 when 1 == 1
'''
def compilerConfig = new CompilerConfiguration()
compilerConfig.addCompilationCustomizers(new MyCompilationCustomizer())
GroovyShell groovyShell = new GroovyShell(compilerConfig)
groovyShell.evaluate(script)
}
}
class MyCompilationCustomizer extends CompilationCustomizer {
MyCompilationCustomizer() {
super(CompilePhase.CONVERSION)
}
#Override
void call(SourceUnit source, GeneratorContext context, ClassNode classNode) throws CompilationFailedException {
println 'in compilation customizer'
}
}
The problem is that your code is not syntactically valid. A compilation customizer will not workaround that: to be able to get an AST, on which the customizer will work, you have to produce syntactically correct code. One option is to use a different AntlrParserPlugin, but in general I don't recommend to do it because it will modify the sources before parsing, and therefore create a mismatch between the AST and the actual source.
I am trying to get a simple Groovy verticle compiled but the compiler trips on the fact that it cannot use the "override" keyword.Any suggestion on how i can get the verticles compiled using the "override" keyword?
compile fail.. due the fact it cannot use override
class AppStarterGroovy extends Verticle {
override def start() {
...
}
}
>> Groovyc: unexpected token: override
compile fail.. due the fact that the return type of Verticle is different
class AppStarterGroovy extends Verticle {
def start() {
...
}
}
>> Groovyc: The return type of java.lang.Object start() in com.AppStarterGroovy is incompatible with void start() in org.vertx.java.platform.Verticle
. At [8:5]
compiles ok..
class AppStarterGroovy extends Verticle {
void start() {
...
}
}
Yeah, there's no override keyword in Groovy, that's an error in the documentation and should just be removed.
But if this is Groovy, and you're extending Verticle, you should extend org.vertx.groovy.platform.Verticle
https://github.com/vert-x/mod-lang-groovy/blob/master/src/main/groovy/org/vertx/groovy/platform/Verticle.groovy
Which has def start() in it