feat: apply gitignore for file paths when using use-gitignore option

changelog.d/20241022_155052_jonathan.griffe_gitignore_paths.md

@@ -0,0 +1,3 @@
+### Changed
+
+- The --use-gitignore option now also applies to single files passed as argument.

ggshield/utils/files.py

@@ -54,6 +54,12 @@ def list_files(
     targets: Set[Path] = set()
     for path in paths:
         if path.is_file():
+            if (
+                list_files_mode == ListFilesMode.ALL_BUT_GITIGNORED
+                and is_git_dir(path.parent)
+                and path.name not in git_ls_unstaged(path.parent) + git_ls(path.parent)
+            ):
+                continue
             targets.add(path)
         elif path.is_dir():
             _targets = set()

tests/unit/utils/test_files.py

@@ -143,3 +143,23 @@ def test_get_ignored_files(tmp_path, file_path, expected):
 def test_url_for_path(path: PurePath, expected_url: str):
     url = url_for_path(path)
     assert url == expected_url
+
+
+def test_get_gitignored_files(tmp_path):
+    """
+    GIVEN a file, that is in the .gitignore
+    WHEN listing its content
+    THEN an empty set is returned
+    """
+    Repository.create(tmp_path)
+    file_full_path = tmp_path / "file.txt"
+    write_text(filename=str(tmp_path / ".gitignore"), content="file.txt")
+    write_text(filename=str(file_full_path), content="")
+
+    file_paths = list_files(
+        paths=[file_full_path],
+        exclusion_regexes=set(),
+        list_files_mode=ListFilesMode.ALL_BUT_GITIGNORED,
+    )
+
+    assert file_paths == set()