Test progress tracking for multibyte text files

tests/test_file_progress.py

@@ -0,0 +1,29 @@
+import io
+
+import pytest
+
+from sqlite_utils.utils import UpdateWrapper
+
+
+@pytest.mark.parametrize("encoding", ("utf-8", "utf-16-le", "utf-32-le"))
+def test_update_wrapper_tracks_underlying_bytes(encoding):
+    text = "id,name\r\n1,Café\r\n2,猫\r\n"
+    raw = text.encode(encoding)
+    updates = []
+    decoded = io.TextIOWrapper(io.BytesIO(raw), encoding=encoding)
+
+    lines = list(UpdateWrapper(decoded, updates.append))
+
+    assert lines == ["id,name\n", "1,Café\n", "2,猫\n"]
+    assert sum(updates) == len(raw)
+
+
+def test_update_wrapper_read_tracks_underlying_bytes():
+    raw = "é猫".encode("utf-8")
+    updates = []
+    decoded = io.TextIOWrapper(io.BytesIO(raw), encoding="utf-8")
+    wrapped = UpdateWrapper(decoded, updates.append)
+
+    assert wrapped.read(1) == "é"
+    assert wrapped.read() == "猫"
+    assert sum(updates) == len(raw)