Google Cloud Shell has application default credentials from its compute instance which will allow you to run an integration test without having to obtain GOOGLE_APPLICATION_CREDENTIALS.

However, tests require an additional environment variable GOOGLE_CLOUD_PROJECT_NUMBER to run. For instance,

In QuickStartIT.java:

private static final String GOOGLE_CLOUD_PROJECT_NUMBER =
       System.getenv("GOOGLE_CLOUD_PROJECT_NUMBER");

Here, the program needs you to provide your Google Cloud Project Number in an environment variable.

To run a sample's integration test in Cloud Shell:

1. cd samples/ - all samples are located in java-pubsublite/samples/snippets directory.

2. mvn clean -Dtest=QuickStartIT test - this runs the integration test for UpdateTopicExample.java.

To run a sample, update the developer's TODO section in the snippet, then:

1. cd samples/snippets/ - all samples are located in java-pubsublite/samples/snippets directory.

2. mvn compile exec:java -Dexec.mainClass=pubsublite.ListTopicsExample - this should list the topics in your project.