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My passion is code quality, automated testing, software craftsmanship.

Using Robolectric in offline mode

The scenario

  • Your CI server doesn’t have direct internet access; or
  • it requires a proxy for internet access
  • and your Robolectric test builds are failing as result…

The problem

The Robolectric test runner downloads some dependency jars that it needs to run at runtime (not compile-time). Normally you don’t even notice this when running your unit tests locally, but this could be a problem on Jenkins/CI if your company doesn’t allow internet access from the CI boxes (as it should be). What happens is, when the Robolectric tests try to run on your CI box, it will fail with a MultipleArtifactsNotFoundException error like the following: > testFoo FAILED
        Caused by: org.apache.maven.artifact.resolver.MultipleArtifactsNotFoundException

Or the error may also look like this:

:app:testDebug > testFoo FAILED
        Caused by: org.apache.maven.artifact.resolver.ArtifactResolutionException
            Caused by: org.apache.maven.artifact.metadata.ArtifactMetadataRetrievalException
                Caused by: org.apache.maven.project.ProjectBuildingException
                    Caused by: org.apache.maven.project.ProjectBuildingException
                        Caused by: org.apache.maven.artifact.resolver.ArtifactNotFoundException
                            Caused by: org.apache.maven.wagon.ResourceDoesNotExistException

1 test completed, 1 failed
:app:testDebug FAILED

If you run gradlew with -i or -d options, you’ll see more details of what’s happening and then you realize it’s because Robolectric is trying to download jars from which you may not have access to if you’re using a local repo such as Artifactory.

We want to stop Robolectric from trying to download its jars from Maven Central and force it to use a local copy of the jars, which we can manually copy to the CI build slave servers.

Robolectric 2.4 introduced two new settings to prevent downloading the dependencies from the hardcoded sonatype / maven URL:

  • robolectric.offline
  • robolectric.dependency.dir

However, it’s not completely clear from the documentation how to use these settings. The documentation just mentions that they’re “system properties”.

There were a few questions I had when I started with this:

  1. Which jars are needed by the Robolectric test runner?
  2. How do I configure these two system properties in my project’s build.gradle file?

The solution

Step 1: Which jars are needed?

In order to place the jars in a known location on the CI build slaves, we first need to figure out exactly which jars are used by Robolectric during run-time.

One way to do this, is to run gradlew testDebug -d (i.e. with debug output) and examine the logs to figure out which jars were downloaded during test run-time.

I decided to take another approach, and go to the Robolectric sources to see which dependencies it needs. The info we want is in

From I could tell that the following four dependencies are needed by Robolectric 3.0 at run-time:

  • org.robolectric:android-all:5.0.0_r2-robolectric-1
  • org.robolectric:shadows-core:3.0-rc2:21
  • org.json:json:20080701
  • org.ccil.cowan.tagsoup:tagsoup:1.2

However, we also need the transitive dependencies of these jars, i.e. the dependencies of these dependencies.

I figured the easiest way to correctly download these 4 jars and all their dependencies, is to let Maven do it. We can create a simple Maven pom.xml file that just lists these 4 dependency artifacts, and then we let mvn dependency:copy-dependencies download everything for us.

I wrote a quick ‘n dirty Python script to generate the pom.xml file for me.

Now I can use the Maven POM file to download the jars that Robolectric needs to a specific directory like /tmp/robolectric-files/:

mvn dependency:copy-dependencies -DremoteRepositories= -DoutputDirectory=/tmp/robolectric-files

These are all the files downloaded by mvn:

$ mvn dependency:copy-dependencies -DremoteRepositories= -DoutputDirectory=/tmp/robolectric-files
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building robolectric-files 3.0-rc2
[INFO] ------------------------------------------------------------------------
[INFO] --- maven-dependency-plugin:2.8:copy-dependencies (default-cli) @ robolectric-files ---
[INFO] Copying vtd-xml-2.11.jar to /tmp/robolectric-files/vtd-xml-2.11.jar
[INFO] Copying accessibility-test-framework-1.0.jar to /tmp/robolectric-files/accessibility-test-framework-1.0.jar
[INFO] Copying tagsoup-1.2.jar to /tmp/robolectric-files/tagsoup-1.2.jar
[INFO] Copying json-20080701.jar to /tmp/robolectric-files/json-20080701.jar
[INFO] Copying robolectric-resources-3.0-rc2.jar to /tmp/robolectric-files/robolectric-resources-3.0-rc2.jar
[INFO] Copying shadows-core-3.0-rc2-21.jar to /tmp/robolectric-files/shadows-core-3.0-rc2-21.jar
[INFO] Copying sqlite4java-0.282.jar to /tmp/robolectric-files/sqlite4java-0.282.jar
[INFO] Copying icu4j-53.1.jar to /tmp/robolectric-files/icu4j-53.1.jar
[INFO] Copying android-all-5.0.0_r2-robolectric-1.jar to /tmp/robolectric-files/android-all-5.0.0_r2-robolectric-1.jar
[INFO] Copying robolectric-annotations-3.0-rc2.jar to /tmp/robolectric-files/robolectric-annotations-3.0-rc2.jar
[INFO] Copying robolectric-utils-3.0-rc2.jar to /tmp/robolectric-files/robolectric-utils-3.0-rc2.jar
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 08:55 min
[INFO] Finished at: 2015-05-13T18:26:23-07:00
[INFO] Final Memory: 13M/239M
[INFO] ------------------------------------------------------------------------

Now copy all those files from /tmp/robolectric-files/ to some known location on your CI build slave box, say to /home/jenkins/robolectric-files (assuming jenkins is your CI build user account).

Step 2: Set the offline-mode System Properties in build.gradle

We need to set the following two Java System Properties for the Robolectric Test Runner to use the local files:

  • robolectric.offline = true
  • robolectric.dependency.dir = /home/jenkins/robolectric-files

One way to do this, is to add the following to our app’s build.gradle file:

afterEvaluate {
    project.tasks.withType(Test) {
        systemProperties.put('robolectric.offline', 'true')
        systemProperties.put('robolectric.dependency.dir', '/home/jenkins/robolectric-files')

Now we can run Gradle and our unit tests completely in offline mode:

$ ./gradlew clean testDebug --offline

(Note: hardcoding a specific user’s home directory in the gradle file isn’t a good idea, but you get the point. Use a directory that works for you.)

Alternate solution:

Instead of Step 2 above, of course you could just install the necessary files into your CI box’s Maven repository (~/.m2/repository/) using something like this for each of them:

mvn install:install-file -DgroupId=org.robolectric \
  -DartifactId=shadows-core -Dversion=3.0-rc2 \
  -Dclassifier=21 -Dpackaging=jar \

But in my solution above I opted for overriding the location of the files using the robolectric.offline and robolectric.dependency.dir system settings, because that way I have more clear control and visibility over which files I’m responsible for maintaining manually.

Update 17 July 2015:

My python script above worked for robolectric-3.0-rc2 but not the final 3.0 version pom.xml… See @benoberkfel’s comment.

Another solution suggested by @nenick:

Create a file called ~/.m2/settings.xml and specify a mirror URL for your local Artifactory/Nexus repository. That way Robolectric will automatically download the required runtime files from your local mirror and no other hacks are required. This seems like a nicer solution depending on your needs. Something like this:

<settings xmlns=""
            <name>mirror of remote repositories</name>
            <url>https://<your address>/nexus/content/groups/public</url>

Also see this related issue on GitHub: Dependency resolution behind proxy #571