Getting ClassNotFoundException when running Robolectric tests with the Maven surefire plugin

Question

I've set up a project in Eclipse using the Android Maven integration, and Robolectric for some tests.

The tests run fine when I deploy them in Eclipse. However, when I try to build the project with the Maven "install" goal (this is actually a library that I need in my local Maven repository), it fails on these same tests.

Logs show the following error:

testAll((package).MyTest)  Time elapsed: 0.006 sec  <<< ERROR!
java.lang.RuntimeException: java.lang.ClassNotFoundException: caught an exception while obtaining a class file for (package).R
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:316)
    at com.xtremelabs.robolectric.RobolectricTestRunner.setupApplicationState(RobolectricTestRunner.java:270)
    at com.xtremelabs.robolectric.RobolectricTestRunner.internalBeforeTest(RobolectricTestRunner.java:221)
    at com.xtremelabs.robolectric.RobolectricTestRunner.methodBlock(RobolectricTestRunner.java:201)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:59)
    at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:120)
    at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:103)
    at org.apache.maven.surefire.Surefire.run(Surefire.java:169)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:350)
    at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:1021)
Caused by: java.lang.ClassNotFoundException: caught an exception while obtaining a class file for (package).R
    at javassist.Loader.findClass(Loader.java:359)
    at com.xtremelabs.robolectric.bytecode.RobolectricClassLoader.findClass(RobolectricClassLoader.java:60)
    at javassist.Loader.loadClass(Loader.java:311)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at com.xtremelabs.robolectric.bytecode.RobolectricClassLoader.loadClass(RobolectricClassLoader.java:37)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:169)
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:312)
    ... 22 more
Caused by: com.xtremelabs.robolectric.bytecode.IgnorableClassNotFoundException: msg because of javassist.NotFoundException: (package).R
    at com.xtremelabs.robolectric.bytecode.AndroidTranslator.onLoad(AndroidTranslator.java:80)
    at javassist.Loader.findClass(Loader.java:340)
    ... 29 more

where (package) is of course the name of my main package. Here's the relevant section of my POM:

  <dependencies>
    <dependency>
      <groupId>com.google.android</groupId>
      <artifactId>android</artifactId>
      <version>2.1.2</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>com.pivotallabs</groupId>
        <artifactId>robolectric</artifactId>
        <version>0.9.8</version>
        <type>jar</type>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest-core</artifactId>
        <version>1.2</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.8.2</version>
        <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
   <defaultGoal>package</defaultGoal>
    <plugins>
      <plugin>
        <groupId>com.jayway.maven.plugins.android.generation2</groupId>
        <artifactId>maven-android-plugin</artifactId>
        <version>2.8.3</version>
        <configuration>
        <genDirectory>${project.basedir}/gen</genDirectory>
          <androidManifestFile>${project.basedir}/AndroidManifest.xml</androidManifestFile>
          <assetsDirectory>${project.basedir}/assets</assetsDirectory>
          <resourceDirectory>${project.basedir}/res</resourceDirectory>
          <nativeLibrariesDirectory>${project.basedir}/src/main/native</nativeLibrariesDirectory>
          <sdk>
            <platform>7</platform>
          </sdk>
          <deleteConflictingFiles>true</deleteConflictingFiles>
          <undeployBeforeDeploy>true</undeployBeforeDeploy>
        </configuration>
        <extensions>true</extensions>
      </plugin>

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <configuration>
          <source>1.6</source>
          <target>1.6</target>
        </configuration>
      </plugin>

    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.6</version>
        <configuration>
            <excludes>
                <exclude>**/Test*.java</exclude>
            </excludes>
        </configuration>
    </plugin>      
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-javadoc-plugin</artifactId>
        <version>2.8</version>
    </plugin>
    </plugins>
  </build>

As you can see, I've tried adding the "genDirectory" option to the Maven Android plugin. But to no avail.

What am I missing to make the surefire plugin "see" the R class?

One more thing: the R class is not actually referenced by my code.

Answer 1

I also got exactly this issue.

So I compared carefully between RobolectricSample project and my project.

To my surprise, the RobolectricSample project also could NOT work if I didn't run the command line of "mvn clean test" first.

Therefore I analysed the difference and found that the command line compiled the "gen/xxx/R.java" to "target/classes/xxx/R" too.

That's the trick of success so I did the following steps: 1. right click project -> Java Build; 2. change the "{project}/gen" output folder as "target/class" (instead of original "target/android-classes")

That's it and hope this helps.