1 files changed, 48 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/test/test_vendor.py b/python/mozbuild/mozbuild/test/test_vendor.py
new file mode 100644
index 0000000000..07ba088337
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/test_vendor.py
@@ -0,0 +1,48 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import shutil
+import subprocess
+import tempfile
+from unittest.mock import Mock
+
+import mozunit
+from buildconfig import topsrcdir
+
+from mozbuild.vendor.vendor_python import VendorPython
+
+
+def test_up_to_date_vendor():
+    with tempfile.TemporaryDirectory() as work_dir:
+        subprocess.check_call(["hg", "init", work_dir])
+        os.makedirs(os.path.join(work_dir, "third_party"))
+        shutil.copytree(
+            os.path.join(topsrcdir, os.path.join("third_party", "python")),
+            os.path.join(work_dir, os.path.join("third_party", "python")),
+        )
+
+        # Run the vendoring process
+        vendor = VendorPython(
+            work_dir, None, Mock(), topobjdir=os.path.join(work_dir, "obj")
+        )
+        vendor.vendor()
+
+        # Verify that re-vendoring did not cause file changes.
+        # Note that we don't want hg-ignored generated files
+        # to bust the diff, so we exclude them (pycache, egg-info).
+        subprocess.check_call(
+            [
+                "diff",
+                "-r",
+                os.path.join(topsrcdir, os.path.join("third_party", "python")),
+                os.path.join(work_dir, os.path.join("third_party", "python")),
+                "--exclude=__pycache__",
+                "--strip-trailing-cr",
+            ]
+        )
+
+
+if __name__ == "__main__":
+    mozunit.main()