Added test for open_guess_encoding

tests/unit/test_utils.py

@@ -6,6 +6,7 @@ import os
 from repo2docker import utils
 import pytest
 import subprocess
+import tempfile
 
 
 def test_capture_cmd_no_capture_success():
@@ -112,6 +113,14 @@ def test_normalize_doi():
     assert utils.normalize_doi("http://dx.doi.org/10.1234/jshd123") == "10.1234/jshd123"
 
 
+def test_open_guess_encoding():
+    data = "Rică nu știa să zică râu, rățușcă, rămurică."
+    with tempfile.NamedTemporaryFile(mode='wb') as test_file:
+        test_file.write(str.encode(data, "utf-16"))
+        test_file.seek(0)
+        with utils.open_guess_encoding(test_file.name) as fd:
+            assert fd.read() == data
+
 @pytest.mark.parametrize(
     "req, is_local",
     [