diff --git a/tests/test-check-py3-commands.t b/tests/test-check-py3-commands.t
new file mode 100644
--- /dev/null
+++ b/tests/test-check-py3-commands.t
@@ -0,0 +1,14 @@
+#require py3exe
+
+This test helps in keeping a track on which commands we can run on
+Python 3 and see what kind of errors are coming up.
+The full traceback is hidden to have a stable output.
+
+  $ for cmd in version debuginstall ; do
+  >   echo $cmd
+  >   $PYTHON3 `which hg` $cmd 2>&1 2>&1 | tail -1
+  > done
+  version
+  TypeError: str expected, not bytes
+  debuginstall
+  TypeError: str expected, not bytes