Add CLI option to specify config file

src/mdformat/_cli.py

@@ -47,8 +47,16 @@ def run(cli_args: Sequence[str], cache_toml: bool = True) -> int:  # noqa: C901
     renderer_warning_printer = RendererWarningPrinter()
     for path in file_paths:
         read_toml = read_toml_opts if cache_toml else read_toml_opts.__wrapped__
+
+        conf_dir = Path.cwd()
+        if path:
+            conf_dir = path.parent
+        if cli_opts.get("toml_file"):
+            cli_toml_file = resolve_cli_toml_file(cli_opts["toml_file"])
+            conf_dir = cli_toml_file.parent
+
         try:
-            toml_opts, toml_path = read_toml(path.parent if path else Path.cwd())
+            toml_opts, toml_path = read_toml(conf_dir)
         except InvalidConfError as e:
             print_error(str(e))
             return 1
@@ -249,6 +257,7 @@ def make_arg_parser(
             help="exclude files that match the Unix-style glob pattern "
             "(multiple allowed)",
         )
+    parser.add_argument("--toml_file", help="path to desired toml config file")
     extensions_group = parser.add_mutually_exclusive_group()
     extensions_group.add_argument(
         "--extensions",
@@ -503,3 +512,17 @@ def get_source_file_and_line(obj: object) -> tuple[str, int]:
     except (OSError, TypeError):  # pragma: no cover
         lineno = 0
     return filename, lineno
+
+
+def resolve_cli_toml_file(cli_toml_arg: str) -> Path:
+    toml_file = Path(cli_toml_arg).absolute()
+
+    if cli_toml_arg[0].isalnum() or (cli_toml_arg[0] in ["."]):
+        toml_file = (Path.cwd() / cli_toml_arg).absolute()
+
+    if cli_toml_arg[0] == "~":
+        toml_file = (Path.home() / cli_toml_arg.replace("~", "")).absolute()
+
+    if not toml_file.is_file():
+        raise InvalidPath(toml_file)
+    return toml_file

tests/test_cli.py

@@ -1,11 +1,12 @@
 import os
+from pathlib import Path
 import sys
 from unittest.mock import patch
 
 import pytest
 
 import mdformat
-from mdformat._cli import get_plugin_info_str, run, wrap_paragraphs
+from mdformat._cli import InvalidPath, get_plugin_info_str, run, wrap_paragraphs
 from mdformat.plugins import CODEFORMATTERS, PARSER_EXTENSIONS
 from tests.utils import (
     FORMATTED_MARKDOWN,
@@ -512,3 +513,56 @@ def test_no_extensions(tmp_path, monkeypatch):
     file_path.write_text(original_md)
     assert run((str(file_path), "--no-extensions")) == 0
     assert file_path.read_text() == original_md
+
+
+def test_cli_toml(tmp_path):
+    _wrap_num = 5
+    config_path = tmp_path / ".mdformat.toml"
+    config_path.write_text(f"wrap = {_wrap_num}")
+
+    file_path = tmp_path / "test_markdown.md"
+    file_path.write_text(
+        " ".join(["x" * _wrap_num, "o" * _wrap_num, "w" * _wrap_num, "p" * _wrap_num])
+    )
+
+    assert run([str(file_path), f"--toml_file={config_path}"]) == 0
+    assert file_path.read_text() == "xxxxx\nooooo\nwwwww\nppppp\n"
+
+
+def test_cli_toml_alphanum(tmp_path):
+    config_path = "1234/.mdformat.toml"
+
+    file_path = tmp_path / "test_markdown.md"
+    file_path.write_text("text")
+
+    with pytest.raises(InvalidPath) as except_info:
+        run([str(file_path), f"--toml_file={config_path}"])
+    assert except_info.typename == "InvalidPath"
+
+    err_value = except_info.value
+    assert config_path in err_value.path.__str__()
+
+
+def test_cli_toml_home(tmp_path):
+    file_path = tmp_path / "test_markdown.md"
+    file_path.write_text("text")
+
+    with pytest.raises(InvalidPath) as except_info:
+        run([str(file_path), "--toml_file=~"])
+    assert except_info.typename == "InvalidPath"
+
+    err_value = except_info.value
+    assert Path.home() == err_value.path
+
+
+def test_cli_toml_not_exists(tmp_path, capsys):
+    config_path = tmp_path / ".mdformat.toml"
+
+    file_path = tmp_path / "test_markdown.md"
+
+    with pytest.raises(SystemExit) as exc_info:
+        run([str(file_path), f"--toml_file={config_path}"])
+    assert exc_info.value.code == 2
+
+    captured = capsys.readouterr()
+    assert "does not exist" in captured.err