We have a really annoying issue with some flaky tests: they work 9/10 times, but every now and then they fail with a ClassNotFoundException when invoking some Kotlin code:
java.lang.ClassNotFoundException: kotlin.collections.Map
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at my-project.server.config.KConfigLoader.load(KConfigLoader.kt:77)
at my-project.server.config.KConfigLoader.load(KConfigLoader.kt:53)
at my-project.server.config.KConfigLoaderTest.loader_shold_register_unknown_properties(KConfigLoaderTest.kt:65)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
at org.apache.maven.surefire.junitcore.pc.Scheduler$1.run(Scheduler.java:405)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)
This happens on our CI server and sometimes locally. What I do not get is the flakyness aspect. Either the Kotlin standard library is on the classpath or not, right? I don't see how it can randomly fail at times.
Debugging info
Kotlin related stuff in parent pom
ag -C2 kotlin ../pom.xml
35: <kotlin.version>1.5.20</kotlin.version>
36: <kotlin.compiler.incremental>false</kotlin.compiler.incremental>
37-
38- <maven.build.timestamp.format>yyyy-MM-dd'T'HH:mm:ss'Z'</maven.build.timestamp.format>
--
47- </plugin>
48- <plugin>
49: <groupId>org.jetbrains.kotlin</groupId>
50: <artifactId>kotlin-maven-plugin</artifactId>
51: <version>${kotlin.version}</version>
52- <executions>
53- <execution>
--
59- <configuration>
60- <sourceDirs>
61: <sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
62- <sourceDir>${project.basedir}/src/main/java</sourceDir>
63- </sourceDirs>
--
71- <configuration>
72- <sourceDirs>
73: <sourceDir>${project.basedir}/src/test/kotlin</sourceDir>
74- <sourceDir>${project.basedir}/src/test/java</sourceDir>
75- </sourceDirs>
--
229- <dependency>
230- <groupId>com.fasterxml.jackson.module</groupId>
231: <artifactId>jackson-module-kotlin</artifactId>
232- <version>${jackson.version}</version>
233- </dependency>
--
273- </dependency>
274- <dependency>
275: <groupId>org.jetbrains.kotlin</groupId>
276: <artifactId>kotlin-stdlib</artifactId>
277: <version>${kotlin.version}</version>
278- </dependency>
279- <dependency>
280: <groupId>org.jetbrains.kotlin</groupId>
281: <artifactId>kotlin-test-junit</artifactId>
282: <version>${kotlin.version}</version>
283- </dependency>
284- <dependency>
285: <groupId>org.jetbrains.kotlin</groupId>
286: <artifactId>kotlin-reflect</artifactId>
287: <version>${kotlin.version}</version>
288- </dependency>
289- <dependency>
Plugin config
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-plugin</artifactId>
<version>${kotlin.version}</version>
<executions>
<execution>
<id>compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
<sourceDir>${project.basedir}/src/main/java</sourceDir>
</sourceDirs>
</configuration>
</execution>
<execution>
<id>test-compile</id>
<goals>
<goal>test-compile</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>${project.basedir}/src/test/kotlin</sourceDir>
<sourceDir>${project.basedir}/src/test/java</sourceDir>
</sourceDirs>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<release>${jdk.version}</release>
<source>${jdk.version}</source>
<target>${jdk.version}</target>
<encoding>${project.build.sourceEncoding}</encoding>
<!--https://issues.apache.org/jira/browse/MCOMPILER-209-->
<useIncrementalCompilation>false</useIncrementalCompilation>
<compilerArgs>
<arg>-Xlint:all</arg>
<!--Silence class version ignore/deprecation warnings -->
<arg>-Xlint:-classfile</arg>
<!-- http://jdbi.org/#_compiling_with_parameter_names -->
<arg>-parameters</arg>
</compilerArgs>
<showWarnings>true</showWarnings>
<showDeprecation>true</showDeprecation>
</configuration>
<executions>
<!-- Replacing default-compile as it is treated specially by maven -->
<execution>
<id>default-compile</id>
<phase>none</phase>
</execution>
<!-- Replacing default-testCompile as it is treated specially by maven -->
<execution>
<id>default-testCompile</id>
<phase>none</phase>
</execution>
<execution>
<id>java-compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>java-test-compile</id>
<phase>test-compile</phase>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
Kotlin related in project pom
Pretty much everything happens in the parent pom wrt setup.
369- <dependency>
370: <groupId>org.jetbrains.kotlin</groupId>
371: <artifactId>kotlin-stdlib</artifactId>
372- </dependency>
373- <dependency>
374: <groupId>org.jetbrains.kotlin</groupId>
375: <artifactId>kotlin-reflect</artifactId>
376- </dependency>
Output from dependency:tree
This is what I get when running mvn dependency:tree -Dincludes=*jetbrains* in the folder containing the root pom:
22:39:55,407 [INFO] Scanning for projects...
22:39:55,542 [INFO] ------------------------------------------------------------------------
22:39:55,542 [INFO] Reactor Build Order:
22:39:55,542 [INFO]
22:39:55,547 [INFO] my-project [pom]
22:39:55,547 [INFO] my-project-commons [jar]
22:39:55,547 [INFO] my-project-my-app-backend [jar]
22:39:55,547 [INFO] my-project-people-backend [jar]
22:39:55,957 [INFO]
22:39:55,958 [INFO] ----------------------< no.ACME.my-project:my-project >-----------------------
22:39:55,959 [INFO] Building my-project 0.0.1-SNAPSHOT [1/4]
22:39:55,959 [INFO] --------------------------------[ pom ]---------------------------------
22:39:55,971 [INFO]
22:39:55,971 [INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ my-project ---
22:39:57,889 [INFO]
22:39:57,891 [INFO] ------------------< no.ACME.my-project:my-project-commons >-------------------
22:39:57,892 [INFO] Building my-project-commons 0.0.1-SNAPSHOT [2/4]
22:39:57,892 [INFO] --------------------------------[ jar ]---------------------------------
22:39:58,354 [INFO]
22:39:58,354 [INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ my-project-commons ---
22:39:58,385 [INFO] no.ACME.my-project:my-project-commons:jar:0.0.1-SNAPSHOT
22:39:58,385 [INFO] +- com.fasterxml.jackson.module:jackson-module-kotlin:jar:2.12.2:compile
22:39:58,385 [INFO] | \- org.jetbrains.kotlin:kotlin-reflect:jar:1.5.20:compile
22:39:58,385 [INFO] | \- org.jetbrains.kotlin:kotlin-stdlib:jar:1.5.20:compile
22:39:58,385 [INFO] | +- org.jetbrains:annotations:jar:21.0.1:compile
22:39:58,385 [INFO] | \- org.jetbrains.kotlin:kotlin-stdlib-common:jar:1.5.20:compile
22:39:58,385 [INFO] \- org.jetbrains.kotlin:kotlin-test-junit:jar:1.5.20:test
22:39:58,385 [INFO] \- org.jetbrains.kotlin:kotlin-test:jar:1.5.20:test
22:39:58,386 [INFO]
22:39:58,386 [INFO] ---------------< no.ACME.my-project:my-project-my-app-backend >---------------
22:39:58,386 [INFO] Building my-project-my-app-backend 0.0.1-SNAPSHOT [3/4]
22:39:58,386 [INFO] --------------------------------[ jar ]---------------------------------
22:39:59,524 [INFO]
22:39:59,525 [INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ my-project-my-app-backend ---
22:39:59,568 [INFO] no.ACME.my-project:my-project-my-app-backend:jar:0.0.1-SNAPSHOT
22:39:59,568 [INFO] +- org.jetbrains.kotlin:kotlin-stdlib:jar:1.5.20:compile
22:39:59,568 [INFO] | +- org.jetbrains:annotations:jar:21.0.1:compile
22:39:59,569 [INFO] | \- org.jetbrains.kotlin:kotlin-stdlib-common:jar:1.5.20:compile
22:39:59,569 [INFO] \- org.jetbrains.kotlin:kotlin-reflect:jar:1.5.20:compile
22:39:59,569 [INFO]
22:39:59,569 [INFO] ---------------< no.ACME.my-project:my-project-people-backend >---------------
22:39:59,569 [INFO] Building my-project-people-backend 0.0.1-SNAPSHOT [4/4]
22:39:59,569 [INFO] --------------------------------[ jar ]---------------------------------
22:39:59,656 [INFO]
22:39:59,657 [INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ my-project-people-backend ---
22:39:59,670 [INFO] no.ACME.my-project:my-project-people-backend:jar:0.0.1-SNAPSHOT
22:39:59,671 [INFO] +- no.ACME.my-project:my-project-commons:jar:0.0.1-SNAPSHOT:compile
22:39:59,671 [INFO] | \- com.fasterxml.jackson.module:jackson-module-kotlin:jar:2.12.2:compile
22:39:59,671 [INFO] | \- org.jetbrains.kotlin:kotlin-reflect:jar:1.5.20:compile
22:39:59,671 [INFO] \- xyz.capybara:clamav-client:jar:2.0.2:compile
22:39:59,671 [INFO] \- org.jetbrains.kotlin:kotlin-stdlib:jar:1.5.20:compile
22:39:59,671 [INFO] +- org.jetbrains:annotations:jar:21.0.1:compile
22:39:59,671 [INFO] \- org.jetbrains.kotlin:kotlin-stdlib-common:jar:1.5.20:compile
22:39:59,671 [INFO] ------------------------------------------------------------------------
22:39:59,671 [INFO] Reactor Summary for my-project 0.0.1-SNAPSHOT:
22:39:59,671 [INFO]
22:39:59,674 [INFO] my-project ............................................. SUCCESS [ 1.932 s]
22:39:59,677 [INFO] my-project-commons ..................................... SUCCESS [ 0.497 s]
22:39:59,677 [INFO] my-project-my-app-backend .............................. SUCCESS [ 1.183 s]
22:39:59,678 [INFO] my-project-people-backend .............................. SUCCESS [ 0.102 s]
22:39:59,678 [INFO] ------------------------------------------------------------------------
22:39:59,678 [INFO] BUILD SUCCESS
22:39:59,678 [INFO] ------------------------------------------------------------------------
22:39:59,679 [INFO] Total time: 4.295 s
22:39:59,681 [INFO] Finished at: 2021-09-14T22:39:59+02:00
22:39:59,686 [INFO] ------------------------------------------------------------------------
Maven version
When this happens, it is usually on TeamCity when running Maven, but we sometimes see it in IntelliJ (not via Maven) as well.
Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d)