diff --git a/tests/test_io.py b/tests/test_io.py
new file mode 100644
index 000000000..4a51bcd0d
--- /dev/null
+++ b/tests/test_io.py
@@ -0,0 +1,13 @@
+import os
+import unittest
+from unittest.mock import patch
+from aider.io import InputOutput
+
+class TestInputOutput(unittest.TestCase):
+    def test_no_color_environment_variable(self):
+        with patch.dict(os.environ, {"NO_COLOR": "1"}):
+            io = InputOutput()
+            self.assertFalse(io.pretty)
+
+if __name__ == "__main__":
+    unittest.main()