Exclude default config value from the pip-compile header (#1893)

piptools/utils.py

@@ -2,7 +2,6 @@
 
 import collections
 import copy
-import functools
 import itertools
 import json
 import os
@@ -366,6 +365,12 @@ def get_compile_command(click_ctx: click.Context) -> str:
         if option_long_name in COMPILE_EXCLUDE_OPTIONS:
             continue
 
+        # Exclude config option if it's the default one
+        if option_long_name == "--config":
+            default_config = select_config_file(click_ctx.params.get("src_files", ()))
+            if value == default_config:
+                continue
+
         # Skip options without a value
         if option.default is None and not value:
             continue
@@ -594,7 +599,14 @@ def select_config_file(src_files: tuple[str, ...]) -> Path | None:
         ),
         None,
     )
-    return config_file_path
+    if config_file_path is None:
+        return None
+
+    return (
+        config_file_path.relative_to(working_directory)
+        if is_path_relative_to(config_file_path, working_directory)
+        else config_file_path
+    )
 
 
 # Some of the defined click options have different `dest` values than the defaults
@@ -628,7 +640,6 @@ def get_click_dest_for_option(option_name: str) -> str:
 ]
 
 
-@functools.lru_cache()
 def parse_config_file(config_file: Path) -> dict[str, Any]:
     try:
         config = tomllib.loads(config_file.read_text(encoding="utf-8"))
@@ -656,3 +667,14 @@ def parse_config_file(config_file: Path) -> dict[str, Any]:
                 original_option, f"Config key '{original_option}' must be a list"
             )
     return piptools_config
+
+
+def is_path_relative_to(path1: Path, path2: Path) -> bool:
+    """Return True if ``path1`` is relative to ``path2``."""
+    # TODO: remove this function in favor of Path.is_relative_to()
+    #       when we drop support for Python 3.8
+    try:
+        path1.relative_to(path2)
+    except ValueError:
+        return False
+    return True

tests/conftest.py

@@ -473,6 +473,6 @@ def _maker(
 
         config_to_dump = {"tool": {"pip-tools": {pyproject_param: new_default}}}
         config_file.write_text(tomli_w.dumps(config_to_dump))
-        return config_file
+        return config_file.relative_to(tmpdir_cwd)
 
     return _maker

tests/test_utils.py

@@ -386,6 +386,30 @@ def test_get_compile_command(tmpdir_cwd, cli_args, expected_command):
         assert get_compile_command(ctx) == expected_command
 
 
+@pytest.mark.parametrize(
+    ("config_file", "expected_command"),
+    (
+        pytest.param(
+            "pyproject.toml", "pip-compile", id="exclude default pyproject.toml"
+        ),
+        pytest.param(
+            ".pip-tools.toml", "pip-compile", id="exclude default .pip-tools.toml"
+        ),
+        pytest.param(
+            "my-config.toml",
+            "pip-compile --config=my-config.toml",
+            id="include non-default my-config.toml",
+        ),
+    ),
+)
+def test_get_compile_command_with_config(tmpdir_cwd, config_file, expected_command):
+    """Test that get_compile_command excludes or includes config file."""
+    with open(config_file, "w"):
+        pass
+    with compile_cli.make_context("pip-compile", ["--config", config_file]) as ctx:
+        assert get_compile_command(ctx) == expected_command
+
+
 def test_get_compile_command_escaped_filenames(tmpdir_cwd):
     """
     Test that get_compile_command output (re-)escapes ' -- '-escaped filenames.