Resolve #1684: Add support for --extend-skip and --extend-skip-glob

4 files changed, 45 insertions, 6 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ce9f022..b0107444 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ Find out more about isort's release policy [here](https://pycqa.github.io/isort/
   - Implemented #1669: Parallel (`-j`) now defaults to number of CPU cores if no value is provided.
   - Implemented #1668: Added a safeguard against accidental usage against /.
   - Implemented #1638 / #1644: Provide a flag `--overwrite-in-place` to ensure same file handle is used after sorting.
+  - Implemented #1684: Added support for extending skips with `--extend-skip` and `--extend-skip-glob`.
   - Documented #1685: Skip doesn't support plain directory names, but skip_glob does.
 
 ### 5.7.0 December 30th 2020
diff --git a/isort/main.py b/isort/main.py
index 38d9a4bb..5ed22cc2 100644
--- a/isort/main.py
+++ b/isort/main.py
@@ -311,7 +311,7 @@ def _build_arg_parser() -> argparse.ArgumentParser:
     target_group.add_argument(
         "-s",
         "--skip",
-        help="Files that sort imports should skip over. If you want to skip multiple "
+        help="Files that isort should skip over. If you want to skip multiple "
         "files you should specify twice: --skip file1 --skip file2. Values can be "
         "file names, directory names or file paths. To skip all files in a nested path "
         "use --skip-glob.",
@@ -319,9 +319,25 @@ def _build_arg_parser() -> argparse.ArgumentParser:
         action="append",
     )
     target_group.add_argument(
+        "--extend-skip",
+        help="Extends --skip to add additional files that isort should skip over. "
+        "If you want to skip multiple "
+        "files you should specify twice: --skip file1 --skip file2. Values can be "
+        "file names, directory names or file paths. To skip all files in a nested path "
+        "use --skip-glob.",
+        dest="extend_skip",
+        action="append",
+    )
+    target_group.add_argument(
         "--sg",
         "--skip-glob",
-        help="Files that sort imports should skip over.",
+        help="Files that isort should skip over.",
+        dest="skip_glob",
+        action="append",
+    )
+    target_group.add_argument(
+        "--extend-skip-glob",
+        help="Additional files that isort should skip over (extending --skip-glob).",
         dest="skip_glob",
         action="append",
     )
diff --git a/isort/settings.py b/isort/settings.py
index e5293772..a62c27bf 100644
--- a/isort/settings.py
+++ b/isort/settings.py
@@ -121,7 +121,9 @@ class _Config:
     py_version: str = "3"
     force_to_top: FrozenSet[str] = frozenset()
     skip: FrozenSet[str] = DEFAULT_SKIP
+    extend_skip: FrozenSet[str] = frozenset()
     skip_glob: FrozenSet[str] = frozenset()
+    extend_skip_glob: FrozenSet[str] = frozenset()
     skip_gitignore: bool = False
     line_length: int = 79
     wrap_length: int = 0
@@ -267,6 +269,8 @@ class Config(_Config):
     ):
         self._known_patterns: Optional[List[Tuple[Pattern[str], str]]] = None
         self._section_comments: Optional[Tuple[str, ...]] = None
+        self._skips: Optional[FrozenSet[str]] = None
+        self._skip_globs: Optional[FrozenSet[str]] = None
 
         if config:
             config_vars = vars(config).copy()
@@ -274,6 +278,8 @@ class Config(_Config):
             config_vars["py_version"] = config_vars["py_version"].replace("py", "")
             config_vars.pop("_known_patterns")
             config_vars.pop("_section_comments")
+            config_vars.pop("_skips")
+            config_vars.pop("_skip_globs")
             super().__init__(**config_vars)  # type: ignore
             return
 
@@ -521,7 +527,7 @@ class Config(_Config):
         if normalized_path[1:2] == ":":
             normalized_path = normalized_path[2:]
 
-        for skip_path in self.skip:
+        for skip_path in self.skips:
             if posixpath.abspath(normalized_path) == posixpath.abspath(
                 skip_path.replace("\\", "/")
             ):
@@ -529,11 +535,11 @@ class Config(_Config):
 
         position = os.path.split(file_name)
         while position[1]:
-            if position[1] in self.skip:
+            if position[1] in self.skips:
                 return True
             position = os.path.split(position[0])
 
-        for glob in self.skip_glob:
+        for glob in self.skip_globs:
             if fnmatch.fnmatch(file_name, glob) or fnmatch.fnmatch("/" + file_name, glob):
                 return True
 
@@ -574,6 +580,22 @@ class Config(_Config):
         self._section_comments = tuple(f"# {heading}" for heading in self.import_headings.values())
         return self._section_comments
 
+    @property
+    def skips(self) -> FrozenSet[str]:
+        if self._skips is not None:
+            return self._skips
+
+        self._skips = self.skip.union(self.extend_skip)
+        return self._skips
+
+    @property
+    def skip_globs(self) -> FrozenSet[str]:
+        if self._skip_globs is not None:
+            return self._skip_globs
+
+        self._skip_globs = self.skip_glob.union(self.extend_skip_glob)
+        return self._skip_globs
+
     def _parse_known_pattern(self, pattern: str) -> List[str]:
         """Expand pattern if identified as a directory and return found sub packages"""
         if pattern.endswith(os.path.sep):
diff --git a/tests/unit/test_main.py b/tests/unit/test_main.py
index eb197090..86f62db3 100644
--- a/tests/unit/test_main.py
+++ b/tests/unit/test_main.py
@@ -326,7 +326,7 @@ import a
 import b
 """
     )
-    main.main([str(tmpdir), "--skip", "skip.py", "--check"])
+    main.main([str(tmpdir), "--extend-skip", "skip.py", "--check"])
 
     # without filter options passed in should successfully sort files
     main.main([str(python_file), str(should_skip), "--verbose", "--atomic"])