1 files changed, 31 insertions, 0 deletions
diff --git a/python/mach/mach/test/test_mach.py b/python/mach/mach/test/test_mach.py
new file mode 100644
index 0000000000..38379d1b49
--- /dev/null
+++ b/python/mach/mach/test/test_mach.py
@@ -0,0 +1,31 @@
+# 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
+
+from mozunit import main
+
+
+def test_set_isatty_environ(monkeypatch, get_mach):
+    # Make sure the 'MACH_STDOUT_ISATTY' variable gets set.
+    monkeypatch.delenv("MACH_STDOUT_ISATTY", raising=False)
+    monkeypatch.setattr(os, "isatty", lambda fd: True)
+
+    m = get_mach()
+    orig_run = m._run
+    env_is_set = []
+
+    def wrap_run(*args, **kwargs):
+        env_is_set.append("MACH_STDOUT_ISATTY" in os.environ)
+        return orig_run(*args, **kwargs)
+
+    monkeypatch.setattr(m, "_run", wrap_run)
+
+    ret = m.run([])
+    assert ret == 0
+    assert env_is_set[0]
+
+
+if __name__ == "__main__":
+    main()