No longer generate RST output when no test case is itemized

mlx/robot2rst.py

@@ -142,8 +142,16 @@ def main():
 
     parser = ParserApplication(Path(args.robot_file), args.include)
     parser.run()
-    return generate_robot_2_rst(parser, Path(args.rst_file), prefix, relationship_config,
-                                gen_matrix, test_type=test_type, only=args.expression, coverages=coverages)
+    if parser.tests:
+        exit_code = generate_robot_2_rst(parser, Path(args.rst_file), prefix, relationship_config,
+                                         gen_matrix, test_type=test_type, only=args.expression, coverages=coverages)
+    else:
+        msg = f"robot2rst did not generate {args.rst_file} because {args.robot_file} does not contain any test cases"
+        if args.include:
+            msg += f" with tags matching all regexes {args.include}"
+        LOGGER.info(msg)
+        exit_code = 0
+    return exit_code
 
 
 def entrypoint():