Kotlin Koans


#1

I’ve just started with trying learning Kotlin and I’m going through the Kotlin Koans exercises.
I’ve enabled Kotlin support under Android Studio 2.3.2.

When I change the code into kotlin-koans/src/i_introduction/_0_Hello_World/HelloWorld.kt by implementing the required solution and I run the test, it seems the binary of the code under test hasn’t changed as I get the following:

util.NotImplementedException: TODO: **
** Introduction.

** Kotlin Koans project consists of 42 small tasks for you to solve.**
** Typically you’ll have to replace the function invocation ‘todoTaskN()’, which throws an exception,**
** with the correct code according to the problem.**

** Using ‘documentation =’ below the task description you can open the related part of the online documentation.**
** Press ‘Ctrl+Q’(Windows) or ‘F1’(Mac OS) on ‘doc0()’ to call the “Quick Documentation” action;**
** “See also” section gives you a link.**
** You can see the shortcut for the “Quick Documentation” action used in your IntelliJ IDEA**
** by choosing “Help -> Find Action…” (in the top menu), and typing the action name (“Quick Documentation”).**
** The shortcut in use will be written next to the action name.**

** Using ‘references =’ you can navigate to the code mentioned in the task description.**

** Let’s start! Make the function ‘task0’ return “OK”.**


** at util.KotlinUtilKt.TODO(kotlinUtil.kt:4)**
** at i_introduction._0_Hello_World.HelloWorldKt.todoTask0(HelloWorld.kt:6)**
** at i_introduction._0_Hello_World.HelloWorldKt.task0(HelloWorld.kt:30)**
** at i_introduction._0_Hello_World._00_Start.testOk(_00_Start.kt:8)**
** 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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)**
** at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)**
** at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)**
** at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)**
** at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)**
** at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)**
** at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)**
** at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)**
** at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)**
** at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)**
** at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)**
** at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)**
** at org.junit.runners.ParentRunner.run(ParentRunner.java:363)**
** at org.junit.runner.JUnitCore.run(JUnitCore.java:137)**
** at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)**
** at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)**
** at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)**
** at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)**

I need to delete the build artefacts manually to get the binary rebuilt.
I still think I’m doing something wrong, but to be honest I thought it should have been at least as straightforward as running JUnit tests.

Could you please advice?


#2

How exactly are you running the tests?


#3

From Android Studio I click on the green run button shown on the test file, like I would do for JUnit tests.
Here’s a link to the video showing what I’m doing:

Thank you very much in advance.


#4

Please make sure that the “Make before run” option is enabled in the run configuration settngs.


#5

Unfortunately I’ve got that already.


#6

Basically it’s not possible to run a single test from the IDE.
The only way I can run the Koans correctly is by selecting the test task from the Gradle Projects view, which causes all tests to be run.
I wonder why in Java that’s possible but not in Kotlin.
Would it be possible to confirm that this is a bug rather than an expected behaviour please?


#7

I’ve added an issue: https://youtrack.jetbrains.com/issue/KT-18948.