check that our test data has deps

This unit test previously failed to detect a bug because the test data
had no deps.

tests/test_builder/test_content_generator.py

@@ -958,7 +958,9 @@ class TestBuild:
         assert new_mmd.get_module_name().endswith("-devel")
 
         # Check that -devel requires non-devel.
-        for dep in new_mmd.get_dependencies():
+        dependencies = new_mmd.get_dependencies()
+        assert dependencies  # test data must have deps for this to be valid
+        for dep in dependencies:
             requires = []
             for name in dep.get_runtime_modules():
                 for stream in dep.get_runtime_streams(name):