test: failing test for dropping changes for a non-ascii file

src/darker/tests/test_main_drop_changes_on_unedited_lines.py

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+"""Tests for `__main__._drop_changes_on_unedited_lines`"""
+
+from pathlib import Path
+from unittest.mock import Mock
+
+import pytest
+
+from darker.__main__ import _drop_changes_on_unedited_lines
+from darkgraylib.utils import TextDocument
+
+
+@pytest.mark.kwparametrize(
+    dict(
+        content=TextDocument("s =  'reformat'\n"),
+        new_chunks=[(1, ("s =  'reformat'",), ('s = "reformat"',))],
+    ),
+    dict(
+        content=TextDocument('s = "keep"\n'),
+        new_chunks=[(1, ('s = "keep"',), ('s = "keep"',))],
+    ),
+    dict(
+        content=TextDocument("""l1 = "first line"\nl2 =  'second line'\n"""),
+        new_chunks=[
+            (
+                1,
+                ('l1 = "first line"', "l2 =  'second line'"),
+                ('l1 = "first line"', 'l2 = "second line"'),
+            )
+        ],
+    ),
+    dict(
+        content=TextDocument(
+            "# coding: iso-8859-5\n# б\x85б\x86\n", encoding="iso-8859-5"
+        ),
+        new_chunks=[
+            (
+                1,
+                ("# coding: iso-8859-5", "# б\x85б\x86"),
+                ("# coding: iso-8859-5", "# б\x85б\x86"),
+            )
+        ],
+    ),
+)
+def test_unchanged_content(tmp_path, content, new_chunks):
+    """Test that no reformats make it through for unmodified files."""
+    # A mock object that always returns an empty list of changed lines
+    edited_linenums_differ = Mock()
+    edited_linenums_differ.revision_vs_lines = Mock(return_value=[])
+    # The expected result is the same as the input content, unmodified
+    expect = content
+
+    result = _drop_changes_on_unedited_lines(
+        new_chunks,
+        abspath_in_rev2=tmp_path / "file.py",
+        relpath_in_repo=Path("file.py"),
+        edited_linenums_differ=edited_linenums_differ,
+        rev2_content=content,
+        rev2_isorted=content,
+        has_isort_changes=False,
+        has_fstring_changes=False,
+    )
+
+    assert result == expect