Enhance --verbose

CHANGES.md

@@ -7,6 +7,7 @@
 - Improve error message for invalid regular expression (#2678)
 - Fix mapping cases that contain as-expressions, like `case {"key": 1 | 2 as password}`
   (#2686)
+- `--verbose` enhancements (project root, how is config found) (#2526)
 
 ## 21.12b0
 

src/black/__init__.py

@@ -31,6 +31,7 @@
 )
 
 import click
+from click.core import ParameterSource
 from dataclasses import replace
 from mypy_extensions import mypyc_attr
 
@@ -411,7 +412,11 @@ def main(
 ) -> None:
     """The uncompromising code formatter."""
     if config and verbose:
-        out(f"Using configuration from {config}.", bold=False, fg="blue")
+        config_source = ctx.get_parameter_source("config")
+        if config_source in (ParameterSource.DEFAULT, ParameterSource.DEFAULT_MAP):
+            out("Using configuration from project root.", fg="blue")
+        else:
+            out(f"Using configuration in '{config}'.", fg="blue")
 
     error_msg = "Oh no! 💥 💔 💥"
     if required_version and required_version != __version__:
@@ -515,8 +520,21 @@ def get_sources(
     stdin_filename: Optional[str],
 ) -> Set[Path]:
     """Compute the set of files to be formatted."""
+    root, method = find_project_root(src)
+
+    if verbose:
+        if method:
+            out(
+                f"Identified `{root}` as project root containing a {method}.",
+                fg="blue",
+            )
+        else:
+            out(f"Identified `{root}` as project root.", fg="blue")
+        paths = '", "'.join(
+            str(Path(source).resolve().relative_to(root)) for source in src
+        )
+        out(f'Sources to be formatted: "{paths}"', fg="blue")
 
-    root = find_project_root(src)
     sources: Set[Path] = set()
     path_empty(src, "No Path provided. Nothing to do 😴", quiet, verbose, ctx)
 

src/black/files.py

@@ -31,14 +31,19 @@
 
 
 @lru_cache()
-def find_project_root(srcs: Sequence[str]) -> Path:
+def find_project_root(srcs: Sequence[str]) -> Tuple[Path, Optional[str]]:
     """Return a directory containing .git, .hg, or pyproject.toml.
 
     That directory will be a common parent of all files and directories
     passed in `srcs`.
 
     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.
+
+    Returns a tuple with the first element as the project root path and the
+    second element as a string which describes the method by which black
+    found out the project root (None, if `None` of the registered method
+    was used).
     """
     if not srcs:
         srcs = [str(Path.cwd().resolve())]
@@ -58,20 +63,20 @@ def find_project_root(srcs: Sequence[str]) -> Path:
 
     for directory in (common_base, *common_base.parents):
         if (directory / ".git").exists():
-            return directory
+            return directory, ".git directory"
 
         if (directory / ".hg").is_dir():
-            return directory
+            return directory, ".hg directory"
 
         if (directory / "pyproject.toml").is_file():
-            return directory
+            return directory, "pyproject.toml"
 
-    return directory
+    return directory, None
 
 
 def find_pyproject_toml(path_search_start: Tuple[str, ...]) -> Optional[str]:
     """Find the absolute filepath to a pyproject.toml if it exists"""
-    path_project_root = find_project_root(path_search_start)
+    path_project_root, _ = find_project_root(path_search_start)
     path_pyproject_toml = path_project_root / "pyproject.toml"
     if path_pyproject_toml.is_file():
         return str(path_pyproject_toml)

tests/test_black.py

@@ -1321,10 +1321,17 @@ def test_find_project_root(self) -> None:
             src_python.touch()
 
             self.assertEqual(
-                black.find_project_root((src_dir, test_dir)), root.resolve()
+                black.find_project_root((src_dir, test_dir)),
+                (root.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_dir,)),
+                (src_dir.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_python,)),
+                (src_dir.resolve(), "pyproject.toml"),
             )
-            self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
-            self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 
     @patch(
         "black.files.find_user_pyproject_toml",
@@ -1791,7 +1798,7 @@ def test_gitignore_used_as_default(self) -> None:
         src = [base / "b/"]
         assert_collected_sources(src, expected, extend_exclude=r"/exclude/")
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_exclude_for_issue_1572(self) -> None:
         # Exclude shouldn't touch files that were explicitly given to Black through the
         # CLI. Exclude is supposed to only apply to the recursive discovery of files.
@@ -1974,13 +1981,13 @@ def test_symlink_out_of_root_directory(self) -> None:
         child.is_symlink.assert_called()
         assert child.is_symlink.call_count == 2
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin(self) -> None:
         src = ["-"]
         expected = ["-"]
         assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin_filename(self) -> None:
         src = ["-"]
         stdin_filename = str(THIS_DIR / "data/collections.py")
@@ -1992,7 +1999,7 @@ def test_get_sources_with_stdin_filename(self) -> None:
             stdin_filename=stdin_filename,
         )
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
         # Exclude shouldn't exclude stdin_filename since it is mimicking the
         # file being passed directly. This is the same as
@@ -2008,7 +2015,7 @@ def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
             stdin_filename=stdin_filename,
         )
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
         # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
         # file being passed directly. This is the same as
@@ -2024,7 +2031,7 @@ def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
             stdin_filename=stdin_filename,
         )
 
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
         # Force exclude should exclude the file when passing it through
         # stdin_filename