I created a simple Greeting task in Kotlin.
Just like the one in the gradle documentation.
Now I'm adding a simple test to it that looks like this in groovy:
class GreetingTaskTest {
#Test
public void canAddTaskToProject() {
Project project = ProjectBuilder.builder().build()
def task = project.task('greeting', type: GreetingTask)
assertTrue(task instanceof GreetingTask)
}
}
I translated this one into Kotlin except one single bit in this line:
def task = project.task('greeting', type: GreetingTask)
The problematic bit is the second parameter. type: GreetingTask
What does it exactly stand for and how does it translate into Kotlin?
Thx to Opal for leading me to the solution.
In addition to his answer here is the kotlin version of the test:
class GreetingTaskTest {
#Test
public fun canAddTaskToProject() {
val project = ProjectBuilder.builder().build()
val task = project.task(mapOf("type" to GreetingTask::class.java), "greeting")
assertTrue(task is GreetingTask)
}
}
Have a look at the docs. task method takes a String and a Map. greeting is an instance of String and type: GreetingTask is a named parameter which is converted to an instance of Map. So you should pass a Map as the second arg. Unfortunately, don't know how to declare a Map in kotlin. This method might be helpful.
Related
Trying to use JUnit 5 class Assertions, specifically assertAll() with Groovy.
Basic Java proves the following syntax:
#Test
public void someTest() {
assertAll('heading',
() -> assertTrue(firstName),
() -> assertTrue(lastName)
);
}
Since I'm stuck to Groovy v2.4, which does not support lambdas, what I do looks like (tried several options, however all of those provide the same error):
#Test
void 'Some test'() {
assertAll('heading',
{ -> assert firstName },
{ -> assert lastName }
)
}
Error message:
groovy.lang.MissingMethodException:
No signature of method: static org.junit.jupiter.api.Assertions.assertAll() is applicable for argument
types: (path.GeneralTests$_Some_test_closure10...)
values: [path.GeneralTests$_Some_test_losure10#1ef13eab, ...]
Looks like the problem is with assertAll() method itself, exception is quite obvious, however that's quite a challenge to get the possible solution, since I had to switch to Groovy from Python just recently.
Indeed, I am going to take some courses with Groovy in future, but you know, you always have to provide results for yesterday.
Would highly appreciate your suggestions!
In this particular case, you need to cast Groovy closure to org.junit.jupiter.api.function.Executable interface explicitly:
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.function.Executable
import static org.junit.jupiter.api.Assertions.*
class Test {
#Test
void 'Some test'() {
assertAll('heading',
{ assertTrue(true) } as Executable,
{ assertFalse(false) } as Executable)
}
}
I'm going through this example but something about it is very confusing to me: https://www.testcookbook.com/book/groovy/jenkins/intro-testing-job-dsl.html
In this test, how/what is executing getJobFiles()? I don't see it being called anywhere. Is there some magic with jobFiles? Is specifying jobFiles somehow calling getJobFiles?
import javaposse.jobdsl.dsl.DslScriptLoader
import javaposse.jobdsl.plugin.JenkinsJobManagement
import org.junit.ClassRule
import org.jvnet.hudson.test.JenkinsRule
import spock.lang.Shared
import spock.lang.Specification
import spock.lang.Unroll
class JobScriptsSpec extends Specification {
#Shared
#ClassRule
JenkinsRule jenkinsRule = new JenkinsRule()
#Unroll
def 'test script #file.name'(File file) {
given:
def jobManagement = new JenkinsJobManagement(System.out, [:], new File('.'))
when:
new DslScriptLoader(jobManagement).runScript(file.text)
then:
noExceptionThrown()
where:
file << jobFiles
}
static List<File> getJobFiles() {
List<File> files = []
new File('jobs').eachFileRecurse {
if (it.name.endsWith('.groovy')) {
files << it
}
}
files
}
}
Edit
It seems like jobFiles does call getJobFiles() but I don't understand how. Is this a groovy or spock feature? I've been trying to research this but can finding anything explaining this in detail.
This is standard Groovy functionality. You can abbreviate any getter call like
def file = new File("sarek-test-parent/sarek-test-common/src/main/java")
println file.name // getName()
println file.parent // getParent()
println file.absolutePath // getAbsolutePath()
println file.directory // isDirectory()
java
sarek-test-parent\sarek-test-common\src\main
C:\Users\alexa\Documents\java-src\Sarek\sarek-test-parent\sarek-test-common\src\main\java
true
The same works for setters:
new Person().name = "John" // setName("John")
new Person().zipCode = "12345" // setZipCode("12345")
Actually the second link provided by jaco0646 explains it, just his mixing up this simple fact with data providers clouds the explanation.
Edit
When Groovy determines that jobFiles does not refer to any existing variable, it considers the name as a Groovy property, which then allows it to take advantage of the shortcut notation for accessing properties.
My code as below, refering to the solution in https://stackoverflow.com/a/30308199/3286489
import org.mockito.Mock
import org.mockito.Mockito
import org.mockito.MockitoAnnotations
import org.mockito.Mockito.*
class SimpleClassTest {
private fun <T> anyObject(): T {
Mockito.anyObject<T>()
return uninitialized()
}
private fun <T> uninitialized(): T = null as T
lateinit var simpleObject: SimpleClass
#Mock lateinit var injectedObject: InjectedClass
#Before
fun setUp() {
MockitoAnnotations.initMocks(this)
}
#Test
fun testSimpleFunction() {
simpleObject = SimpleClass(injectedObject)
verify(injectedObject).settingDependentObject(anyObject())
}
}
I still have the below error
java.lang.IllegalArgumentException: Parameter specified as non-null is null: method my.package.InjectedClass.settingDependentObject, parameter dependentObject
Did I miss anything?
UPDATED
Below is the code tested (simplest form and working)
class SimpleClass(val injectedClass: InjectedClass) {
fun simpleFunction() {
injectedClass.settingDependentObject(DependentClass(Response.Builder().build()))
}
}
open class DependentClass(response: Response) {
}
open class InjectedClass() {
lateinit var dependentObject: DependentClass
fun settingDependentObject(dependentObject: DependentClass) {
this.dependentObject = dependentObject
}
}
By default Kotlin classes and members are final. Mockito cannot mock final classes or methods.
Thus when you write:
verify(injectedObject).settingDependentObject(anyObject())
the real implementation is called which requires non null argument.
To fix that either open your class and method or, even better, change SimpleClass to accept an interface as its constructor argument and mock the interface instead.
There is a project specifically to help deal with Kotlin "closed by default" in unit testing with Mockito. For JUNIT, you can use the kotlin-testrunner which is an easy way to make any Kotlin test automatically open up classes for testing as they are loaded by the classloader. Usage is simple, just add one annotation of #RunWith(KotlinTestRunner::class), for example:
#RunWith(KotlinTestRunner::class)
class MyKotlinTestclass {
#Test
fun test() {
...
}
}
This is thoroughly covered in the article Never say final: mocking Kotlin classes in unit tests
This covers your use case in an automatic way by allowing all classes to be mocked that otherwise would not be allowed.
I ran into the same issue with Mockito when using RETURNS_DEEP_STUBS. It seems like nulls are still returned for nested objects, even when using the kotlin-allopen plugin.
Please check out and comment on this issue on Mockito if you're having the same problem.
You can use this function instead
inline fun <reified T : Any> any(): T = Mockito.any(T::class.java) ?: T::class.java.newInstance()
So I want to add methods to JDK classes like InputStream, File, etc. I'm trying to figure out what is the best way to do that, but it seems there are several options for doing it. One way is do this by adding methods into the metaClass property on the Class like so:
InputStream.metaClass.copy = { OutputStream out ->
long total = 0
byte[] buffer = new byte[8096]
int len
while ((len = read(buffer)) >= 0) {
out.write(buffer, 0, len)
total += len
}
out.flush()
return delegate
}
Another way is using dynamic mixins like this:
class EnhancedInputStream {
static {
InputStream.metaClass.mixin( EnhancedInputStream )
}
public InputStream copy( OutputStream out ) {
long total = 0
byte[] buffer = new byte[8096]
int len
while ((len = mixinOwner.read(buffer)) >= 0) {
out.write(buffer, 0, len)
total += len
}
out.flush()
return mixinOwner
}
}
So the first question is do dynamic Mixins replace the use of using metaClass + Closure to create mixins? The examples of dynamic mixins don't really discuss scoping rules in any detail that I can find. Which leads me to the next point.
You can see in the first code sample using metaClass I used delegate to get access to the this pointer of the class I was adding methods to. What is the equivalent way to do that using dynamic Mixins? All examples I've found are stateless (pointless really). I found one example mentioning a special member mixinOwner that could be used in place of delegate. Is that true?
Second you'll see I used a static block in EnhancedInputStream to add the mixin dynamically to InputStream. When using metaClass what is the best way to add those? Another static block with import statement?
I suppose I really want just a compile time Mixin where I can define the #Mixin on the source of the mixin instead of destination because I didn't write the destination. Like
#MixinInto(File)
public class EnhancedFileMixin {
public void zip( File output ) {
// .....
}
}
But that doesn't appear to exist in Groovy land. So what's the best approach to reach this using metaClass or dynamic mixins?
I guess the nearest to #MixinInto would be the magic package convention. I couldn't mix it into a interface, but i managed to mix it into a FileInputStream, if that suits your case. I guess you can add state using the MetaClass which comes in the constructor.
To write a class to be mixed into InputStream. It needs to be:
In the package groovy.runtime.metaclass.java.io
Named FileInputStreamMetaClass (exactly)
Compiled and put into the classpath
Extend DelegatingMetaClass
It can only intercept the GroovyObject methods, so it is not so straightforward. If you are in for a pure dynamic groovy, it is great:
package groovy.runtime.metaclass.java.io
class FileInputStreamMetaClass extends DelegatingMetaClass {
FileInputStreamMetaClass(MetaClass meta) {
super(meta)
println "built FileInputStreamMetaClass"
}
Object invokeMethod(Object delegate, String method, Object[] args) {
switch (method) {
case "copy":
return "i'm copying stuff"
default:
return super.invokeMethod(delegate, method, args)
}
}
}
Compiling:
$ groovyc FileInputStreamMetaClass.groovy
$ groovy -cp . InputTest.groovy
A test:
InputStream input = new FileInputStream("/tmp/test.tmp")
assert input.copy() == "i'm copying stuff"
A bit cumbersome.
I'd go for Extensions any time of the day. Three files:
// file META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
moduleName=InputExtensionModule
moduleVersion=0.1
extensionClasses=InputStreamExtension
The extension:
class InputStreamExtension {
static String copy(InputStream input) {
"copying stuff, doc"
}
}
The test:
def input = new FileInputStream("/tmp/test.tmp")
assert input.copy() == "copying stuff, doc"
Compile and run:
$ groovyc InputStreamExtension.groovy
$ groovy ISExtensionTest.groovy
And i think the extension is the perfect place to use the static { mixin } block. With some changes:
class InputStreamExtension {
static {
InputStream.mixin InputStreamMixin
}
static String copy(InputStream input) { "copying stuff, doc" }
}
#Category(InputStream)
class InputStreamMixin {
Object pop() {
"input mixin pop"
}
}
A new test:
def input = new FileInputStream("/tmp/test.tmp")
assert input.copy() == "copying stuff, doc"
assert input.pop() == "input mixin pop"
Well I finally figured it out on my own. Essentially the this reference refers to the instance of the Mixin which doesn't do us much good. However, you can use the "as" keyword to convert that to the instance of the target class. For example:
class MyMixin {
static {
File mixin MyMixin
}
File foo() {
return this as File
}
}
File f = new File()
println( f.foo().equals( f ) )
As for mixinOwner and owner references that the jira bug refers to. They don't exist. This is the only way to get a reference to the instance that the mixin was added to.
I wrote up a longer blogpost about it because I thought this was important information for future Groovy programmers since there is zero official docs discussing this.
http://wrongnotes.blogspot.com/2013/06/groovy-mixins-and-this-pointer.html
I am glad you asked this question. To answer a very important question:
I suppose I really want just a compile time Mixin where I can define the #Mixin on the source of the mixin instead of destination because I didn't write the destination.
You cannot achieve this by #Mixin but we do have something in Groovy which will help you out. It is called #Category. Let me go through your example again to show you how you can actually effectively use this in category. Have a look at the below script:
#Category(InputStream)
class InputStreamCategory{
def copy(OutputStream out){
long total = 0
byte[] buffer = new byte[8096]
int len
while ((len = this.read(buffer)) >= 0) {
out.write(buffer, 0, len)
total += len
}
out.flush()
return this
}
}
class MyUtil{
def str = 'This is a dummy String!!!!'
InputStream inputS = new ByteArrayInputStream(str.bytes)
OutputStream outputS = new ByteArrayOutputStream()
def copy(){
use(InputStreamCategory){
inputS.copy(outputS)
println "Printing Output Stream: " + outputS
}
}
}
def util = new MyUtil()
util.copy()
//Prints:
Printing Output Stream: This is a dummy String!!!!
Explanation:-
#Category(InputStream) sets the this in InputStreamCategory and in your util class you just use the newly added method copy to InputStream. The benefit for using category is that you get hold of the caller object in this case inputS. The first parameter passed into a category always refers to the caller. You can have different categories for different implementations like FileCategory etc and then create an Utility Class to use those Categories. Therefore, you would end up with utilities like zip, copy, etc.
You could get detail information about the same from the api. I also highly recommend going through Category and Mixin Transformations.
To answer the first question:-
do dynamic Mixins replace the use of using metaClass + Closure to create mixins?
No they do not. metaClass implementation does not create a Mixin. It just adds another method in the metaData registry about the class while runtime. You get an handle to the delegate. On the other hand #Mixin gives you the ability to inherit pre-defined properties.
I am trying to override the functionality of a method of a java type instance in my Groovy code but I am getting a classcast exception.
I looked at the guide posted here but I can not get it to work.
Since my actual problem is a bit of mess, below is some runnable example code that fails with the same error.
In the example I want to override the substring method of an instance of the java.lang.String class. In reality I want to override a method of an instance of a class that does not have a corresponding Groovy implementation, so the answer to my example is not to simply use a Groovy string instance.
class example {
static void main(args) {
java.lang.String hey = new java.lang.String("hey")
ExpandoMetaClass emc = new ExpandoMetaClass( java.lang.String, false )
emc.substring = {
"This is not a very good substring implementation"
}
emc.initialize()
def proxiedHey = new groovy.util.Proxy().wrap(hey)
proxiedHey.setMetaClass(emc)
printf proxiedHey.toString()
printf proxiedHey.substring(1)
}
}
The above example fails at line 12, i.e printf meh.toString(). The exception thrown is
Caught: java.lang.ClassCastException:
groovy.util.Proxy cannot be cast to
java.lang.CharSequence at
example.main(test.groovy:12)
So, any ideas on what I am doing wrong or if there is another way to solve my problem of adding and/or overriding methods of a java type instance?
I am using Groovy version 1.7.4.
You are creating an ExpandoMetaClass for java.lang.String, but assigning it to a groovy.util.Proxy. Make a metaClass for groovy.util.Proxy instread, like so:
java.lang.String hey = new java.lang.String("hey")
def proxiedHey = new groovy.util.Proxy().wrap(hey)
ExpandoMetaClass emc = new ExpandoMetaClass( groovy.util.Proxy, false )
emc.substring = {
"This is not a very good substring implementation"
}
emc.initialize()
proxiedHey.setMetaClass(emc)
printf proxiedHey.toString()
printf proxiedHey.substring(1)
Have you looked at Pimp my Library Pattern which allows you to add using Groovy Categories. You might find it more convenient and easy to understand in your case.
#Category(String)
class StringSubstrCategory {
def substring( int n) {
"This is not a very good substring implementation"
}
}
use (StringSubstrCategory) {
"hey".substring(1)
}