From 36bed855e11b119adc4cd5b3ad87e2da965928ba Mon Sep 17 00:00:00 2001
From: =?utf8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Mon, 4 Jun 2018 10:59:36 -0700
Subject: [PATCH 1/1] Introduce "project root" as a concept

This is required for regular expressions in `--include=` and `--exclude=` not
to catch false positives from directories outside of the project.
---
 black.py            | 41 +++++++++++++++++++++++++++++++++++++----
 tests/test_black.py |  9 ++++++---
 2 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/black.py b/black.py
index da00525..730c64d 100644
--- a/black.py
+++ b/black.py
@@ -253,10 +253,13 @@ def main(
     except re.error:
         err(f"Invalid regular expression for exclude given: {exclude!r}")
         ctx.exit(2)
+    root = find_project_root(src)
     for s in src:
         p = Path(s)
         if p.is_dir():
-            sources.extend(gen_python_files_in_dir(p, include_regex, exclude_regex))
+            sources.extend(
+                gen_python_files_in_dir(p, root, include_regex, exclude_regex)
+            )
         elif p.is_file():
             # if a file was explicitly given, we don't care about its extension
             sources.append(p)
@@ -2792,13 +2795,14 @@ def get_future_imports(node: Node) -> Set[str]:
 
 
 def gen_python_files_in_dir(
-    path: Path, include: Pattern[str], exclude: Pattern[str]
+    path: Path, root: Path, include: Pattern[str], exclude: Pattern[str]
 ) -> Iterator[Path]:
     """Generate all files under `path` whose paths are not excluded by the
     `exclude` regex, but are included by the `include` regex.
     """
+    assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
     for child in path.iterdir():
-        normalized_path = child.resolve().as_posix()
+        normalized_path = child.resolve().relative_to(root).as_posix()
         if child.is_dir():
             normalized_path += "/"
         exclude_match = exclude.search(normalized_path)
@@ -2806,7 +2810,7 @@ def gen_python_files_in_dir(
             continue
 
         if child.is_dir():
-            yield from gen_python_files_in_dir(child, include, exclude)
+            yield from gen_python_files_in_dir(child, root, include, exclude)
 
         elif child.is_file():
             include_match = include.search(normalized_path)
@@ -2814,6 +2818,35 @@ def gen_python_files_in_dir(
                 yield child
 
 
+def find_project_root(srcs: List[str]) -> Path:
+    """Return a directory containing .git, .hg, or pyproject.toml.
+
+    That directory can be one of the directories passed in `srcs` or their
+    common parent.
+
+    If no directory in the tree contains a marker that would specify it's the
+    project root, the root of the file system is returned.
+    """
+    if not srcs:
+        return Path("/").resolve()
+
+    common_base = min(Path(src).resolve() for src in srcs)
+    if common_base.is_dir():
+        # Append a fake file so `parents` below returns `common_base_dir`, too.
+        common_base /= "fake-file"
+    for directory in common_base.parents:
+        if (directory / ".git").is_dir():
+            return directory
+
+        if (directory / ".hg").is_dir():
+            return directory
+
+        if (directory / "pyproject.toml").is_file():
+            return directory
+
+    return directory
+
+
 @dataclass
 class Report:
     """Provides a reformatting counter. Can be rendered with `str(report)`."""
diff --git a/tests/test_black.py b/tests/test_black.py
index 7e50c2f..7389da9 100644
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -864,7 +864,8 @@ class BlackTestCase(unittest.TestCase):
             Path(THIS_DIR / "include_exclude_tests/b/dont_exclude/a.py"),
             Path(THIS_DIR / "include_exclude_tests/b/dont_exclude/a.pyi"),
         ]
-        sources.extend(black.gen_python_files_in_dir(path, include, exclude))
+        this_abs = THIS_DIR.resolve()
+        sources.extend(black.gen_python_files_in_dir(path, this_abs, include, exclude))
         self.assertEqual(sorted(expected), sorted(sources))
 
     def test_empty_include(self) -> None:
@@ -882,9 +883,10 @@ class BlackTestCase(unittest.TestCase):
             Path(path / "b/.definitely_exclude/a.py"),
             Path(path / "b/.definitely_exclude/a.pyi"),
         ]
+        this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files_in_dir(
-                path, empty, re.compile(black.DEFAULT_EXCLUDES)
+                path, this_abs, empty, re.compile(black.DEFAULT_EXCLUDES)
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
@@ -901,9 +903,10 @@ class BlackTestCase(unittest.TestCase):
             Path(path / "b/.definitely_exclude/a.py"),
             Path(path / "b/.definitely_exclude/a.pyi"),
         ]
+        this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files_in_dir(
-                path, re.compile(black.DEFAULT_INCLUDES), empty
+                path, this_abs, re.compile(black.DEFAULT_INCLUDES), empty
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
-- 
2.39.5