Separate a test case of apply_flynt()

src/darker/tests/test_fstring.py

@@ -32,12 +32,8 @@ def test_fstring_importable_with_and_without_flynt(present):
 
 @pytest.mark.parametrize("encoding", ["utf-8", "iso-8859-1"])
 @pytest.mark.parametrize("newline", ["\n", "\r\n"])
-@pytest.mark.kwparametrize(
-    dict(exclude=set(), expect=FLYNTED_SOURCE),
-    dict(exclude={"**/*"}, expect=MODIFIED_SOURCE),
-)
-def test_apply_flynt_exclude(git_repo, encoding, newline, exclude, expect):
-    """Flynt skipped if path matches exclusion patterns, encoding and newline intact"""
+def test_apply_flynt_exclude(git_repo, encoding, newline):
+    """Encoding and newline are intact after Flynt fstringification"""
     git_repo.add({"test1.py": joinlines(ORIGINAL_SOURCE, newline)}, commit="Initial")
     edited_linenums_differ = EditedLinenumsDiffer(
         git_repo.root, RevisionRange("HEAD", ":WORKTREE:")
@@ -47,10 +43,8 @@ def test_apply_flynt_exclude(git_repo, encoding, newline, exclude, expect):
         MODIFIED_SOURCE, encoding=encoding, newline=newline
     )
 
-    result = darker.fstring.apply_flynt(
-        content_, src, exclude=exclude, edited_linenums_differ=edited_linenums_differ
-    )
+    result = darker.fstring.apply_flynt(content_, src, edited_linenums_differ)
 
-    assert result.lines == expect
+    assert result.lines == FLYNTED_SOURCE
     assert result.encoding == encoding
     assert result.newline == newline

src/darker/tests/test_main.py

@@ -20,6 +20,7 @@
 from darker.exceptions import MissingPackageError
 from darker.git import WORKTREE, EditedLinenumsDiffer, RevisionRange
 from darker.tests.helpers import isort_present
+from darker.tests.test_fstring import FLYNTED_SOURCE, MODIFIED_SOURCE, ORIGINAL_SOURCE
 from darker.utils import TextDocument, joinlines
 from darker.verification import NotEquivalentError
 
@@ -749,6 +750,32 @@ def test_print_diff(tmp_path, capsys):
     ]
 
 
+@pytest.mark.parametrize("encoding", ["utf-8", "iso-8859-1"])
+@pytest.mark.parametrize("newline", ["\n", "\r\n"])
+@pytest.mark.kwparametrize(
+    dict(exclude=set(), expect=FLYNTED_SOURCE),
+    dict(exclude={"**/*"}, expect=MODIFIED_SOURCE),
+)
+def test_maybe_flynt_single_file(git_repo, encoding, newline, exclude, expect):
+    """Flynt skipped if path matches exclusion patterns, encoding and newline intact"""
+    git_repo.add({"test1.py": joinlines(ORIGINAL_SOURCE, newline)}, commit="Initial")
+    edited_linenums_differ = EditedLinenumsDiffer(
+        git_repo.root, RevisionRange("HEAD", ":WORKTREE:")
+    )  # pylint: disable=duplicate-code
+    src = Path("test1.py")
+    content_ = TextDocument.from_lines(
+        MODIFIED_SOURCE, encoding=encoding, newline=newline
+    )
+
+    result = darker.__main__._maybe_flynt_single_file(
+        src, exclude, edited_linenums_differ, content_
+    )
+
+    assert result.lines == expect
+    assert result.encoding == encoding
+    assert result.newline == newline
+
+
 @pytest.mark.kwparametrize(
     dict(new_content=TextDocument(), expect=b""),
     dict(new_content=TextDocument(lines=["touché"]), expect=b"touch\xc3\xa9\n"),