How to run all tests in Bazel from a single java_test() rule?

Question

I am adding tests in Bazel, but I don't want to write a test rule for every single test file. However, each test rule requires a test_class - the test class that is being ran, so there is no easy way to just run all tests with a single java_test rule. Is there a work around for where I wouldn't need to specify a test_class and just run all tests at once?

Answer 1

In Bazel, we wrote a custom Junit Suite that finds all the Junit classes on the classpath in or under the package of the annotated class. You can find the code here. It's pretty short and straight forward and you can copy it into your project or do something similar.

You can then have your rules like this:

java_library(
    name = "tests",
    testonly = 1,
    srcs = glob(["*.java"])
)

java_test(
   name = "MyTests",
   test_class = "MyTests",
   runtime_deps = [":tests"],
)

and the MyTests.java file should look like this:

import package.ClasspathSuite;

import org.junit.runner.RunWith;

@RunWith(ClasspathSuite.class)
public class MyTests { }