From 737e0492d0f30f65d9af9bfc8657fd98822b96f1 Mon Sep 17 00:00:00 2001
From: Anthony Sottile <asottile@umich.edu>
Date: Wed, 7 Apr 2021 08:52:26 -0700
Subject: [PATCH] improve code coverage in a few places

---
 src/flake8/processor.py  | 14 +-------------
 src/flake8/utils.py      |  5 +----
 tests/unit/test_utils.py |  7 +++++++
 3 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/src/flake8/processor.py b/src/flake8/processor.py
index 7c4672a..5fd78a8 100644
--- a/src/flake8/processor.py
+++ b/src/flake8/processor.py
@@ -446,8 +446,6 @@ def log_token(log: logging.Logger, token: _Token) -> None:
     )
 
 
-# NOTE(sigmavirus24): This was taken wholesale from
-# https://github.com/PyCQA/pycodestyle
 def expand_indent(line: str) -> int:
     r"""Return the amount of indentation.
 
@@ -462,17 +460,7 @@ def expand_indent(line: str) -> int:
     >>> expand_indent('        \t')
     16
     """
-    if "\t" not in line:
-        return len(line) - len(line.lstrip())
-    result = 0
-    for char in line:
-        if char == "\t":
-            result = result // 8 * 8 + 8
-        elif char == " ":
-            result += 1
-        else:
-            break
-    return result
+    return len(line.expandtabs(8))
 
 
 # NOTE(sigmavirus24): This was taken wholesale from
diff --git a/src/flake8/utils.py b/src/flake8/utils.py
index c5c134e..96c3485 100644
--- a/src/flake8/utils.py
+++ b/src/flake8/utils.py
@@ -231,9 +231,7 @@ def parse_unified_diff(diff: Optional[str] = None) -> Dict[str, Set[int]]:
     parsed_paths: Dict[str, Set[int]] = collections.defaultdict(set)
     for line in diff.splitlines():
         if number_of_rows:
-            # NOTE(sigmavirus24): Below we use a slice because stdin may be
-            # bytes instead of text on Python 3.
-            if line[:1] != "-":
+            if not line or line[0] != "-":
                 number_of_rows -= 1
             # We're in the part of the diff that has lines starting with +, -,
             # and ' ' to show context and the changes made. We skip these
@@ -317,7 +315,6 @@ def _default_predicate(*args: str) -> bool:
 def filenames_from(
     arg: str, predicate: Optional[Callable[[str], bool]] = None
 ) -> Generator[str, None, None]:
-    # noqa: E501
     """Generate filenames from an argument.
 
     :param str arg:
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 4304057..d31c113 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -313,3 +313,10 @@ def test_stdin_get_value_crlf():
     stdin = io.TextIOWrapper(io.BytesIO(b'1\r\n2\r\n'), 'UTF-8')
     with mock.patch.object(sys, 'stdin', stdin):
         assert utils.stdin_get_value.__wrapped__() == '1\n2\n'
+
+
+def test_stdin_unknown_coding_token():
+    """Ensure we produce source even for unknown encodings."""
+    stdin = io.TextIOWrapper(io.BytesIO(b'# coding: unknown\n'), 'UTF-8')
+    with mock.patch.object(sys, 'stdin', stdin):
+        assert utils.stdin_get_value.__wrapped__() == '# coding: unknown\n'