like to get an error. Currently we do, but if we add the extra <inherits> lines, we
            won't.

            I have one idea for a better approach, but it's painful, and I haven't tested it: We
            could postprocess Collect.gwt.xml to add <skip> lines for all the files that should be
            covered by testModule.gwt.xml. Maybe I'll try it someday.

            <includes>
              <include>${test.include}</include>
            </includes>
            <!-- By having our own entries here, we also override the default exclusion filter, which excludes all nested classes. -->
            <excludes>
              <!-- https://github.com/google/guava/issues/2840 -->
              <exclude>%regex[.*PackageSanityTests.*.class]</exclude>