diff --git a/game/tests/run_tests.gd b/game/tests/run_tests.gd
index 8f305dd..5a0ea89 100644
--- a/game/tests/run_tests.gd
+++ b/game/tests/run_tests.gd
@@ -2,7 +2,8 @@ extends SceneTree
 ## Runs every test script in res://tests whose file name starts with "test_".
 ## Every method whose name starts with "test_" is one test. A test fails if a
 ## check fails or if an error is reported while it runs, for example a call
-## on a null value. Exits with code 1 if any test failed.
+## on a null value. Exits with code 1 if any test failed or if no test ran,
+## so that a renamed test folder or misnamed tests cannot pass as a clean run.
 ##
 ## From the repository root:
 ##   godot --headless --path game -s res://tests/run_tests.gd
@@ -78,4 +79,4 @@ func _run_all() -> void:
 					print("        " + failure)
 	OS.remove_logger(counter)
 	print("%d passed, %d failed" % [passed, failed])
-	quit(1 if failed > 0 else 0)
+	quit(1 if failed > 0 or passed == 0 else 0)