Add --config option

gersemi/__main__.py

@@ -217,6 +217,16 @@ def create_argparser():
     [default: cache enabled]
         """,
     )
+    control_configuration_group.add_argument(
+        "--config",
+        dest="configuration_file",
+        type=pathlib.Path,
+        default=None,
+        help=f"""
+    {control_conf_doc["configuration_file"]}
+    [default: omitted]
+        """,
+    )
 
     parser.add_argument(
         dest="sources",

gersemi/__version__.py

@@ -4,4 +4,4 @@
 __license__ = "MPL 2.0"
 __title__ = "gersemi"
 __url__ = "https://github.com/BlankSpruce/gersemi"
-__version__ = "0.16.2"
+__version__ = "0.17.0-rc1"

gersemi/configuration.py

@@ -100,12 +100,14 @@ class ListExpansion(EnumWithMetadata):
 class OutcomeConfiguration:
     """
     These arguments control how gersemi formats source code.
-    Values for these arguments can be stored in .gersemirc file which should be
-    placed in directory next to the source file or any parent directory with
-    priority on closest configuration file.
+    Values for these arguments can be stored in .gersemirc file which can be
+    placed in directory next to the source file or any parent directory.
+    The highest priority has file provided through --config, then file closest
+    to the source file, then file in parent directory etc. until root of file
+    system is reached.
     Arguments from command line can be used to override parts of that stored
     configuration or supply them in absence of configuration file.
-    Precedence: (command line arguments) > (.gersemirc values) > (defaults)
+    Precedence: (command line arguments) > (configuration file) > (defaults)
     """
 
     line_length: int = field(
@@ -192,7 +194,7 @@ def summary(self):
 class ControlConfiguration:
     """
     These arguments control how gersemi operates rather than how it formats source code.
-    Values for these options are not read from .gersemirc file.
+    Values for these options are not read from configuration file.
     Default values are used when the arguments aren't supplied.
     Precedence: (command line arguments) > (defaults)
     """
@@ -202,7 +204,6 @@ class ControlConfiguration:
         metadata=dict(
             title="Quiet",
             description="Skip printing non-error messages to stderr.",
-            command_line_only=True,
         ),
     )
 
@@ -211,7 +212,6 @@ class ControlConfiguration:
         metadata=dict(
             title="Colorized diff",
             description="If --diff is selected showed diff is colorized.",
-            command_line_only=True,
         ),
     )
 
@@ -226,7 +226,6 @@ class ControlConfiguration:
     files in parallel.
                 """
             ),
-            command_line_only=True,
         ),
     )
 
@@ -240,7 +239,21 @@ class ControlConfiguration:
     to be formatted to speed up execution.
                 """
             ),
-            command_line_only=True,
+        ),
+    )
+
+    configuration_file: Optional[Path] = field(
+        default=None,
+        metadata=dict(
+            title="Configuration file",
+            description=doc(
+                """
+    Path to configuration file. When present this configuration
+    file will be used for determining configuration for all sources
+    instead of automatically found configuration files closest to
+    each of the sources.
+                """
+            ),
         ),
     )
 
@@ -390,12 +403,9 @@ def override_with_args(configuration, args):
 
 
 def make_outcome_configuration(
-    path, args
+    configuration_file, args
 ) -> Tuple[OutcomeConfiguration, NotSupportedKeys]:
-    outcome, not_supported_keys = load_configuration_from_file(
-        find_closest_dot_gersemirc(path)
-    )
-
+    outcome, not_supported_keys = load_configuration_from_file(configuration_file)
     return override_with_args(outcome, args), not_supported_keys
 
 

gersemi/runner.py

@@ -11,6 +11,7 @@
 from gersemi.configuration import (
     Configuration,
     ControlConfiguration,
+    find_closest_dot_gersemirc,
     make_control_configuration,
     make_outcome_configuration,
     MaxWorkers,
@@ -305,7 +306,8 @@ def _inform_about_not_supported_keys(self, item: NotSupportedKeys):
 
     def __call__(self, path: Path) -> Configuration:
         outcome_configuration, not_supported_keys = make_outcome_configuration(
-            path, self.args
+            configuration_file=find_closest_dot_gersemirc(path),
+            args=self.args,
         )
         self._inform_about_not_supported_keys(not_supported_keys)
         return Configuration(control=self.control, outcome=outcome_configuration)
@@ -314,8 +316,11 @@ def __call__(self, path: Path) -> Configuration:
 def split_files_by_configuration(
     paths: Iterable[Path], args: argparse.Namespace, control: ControlConfiguration
 ):
-    result = defaultdict(list)
     helper = ConfigurationHelper(args, control)
+    if control.configuration_file is not None:
+        return {helper(control.configuration_file): paths}
+
+    result = defaultdict(list)
     for path in paths:
         result[helper(path)].append(path)
 

tests/test_executable.py

@@ -1072,3 +1072,35 @@ def test_disable_formatting(app, testfiles):
         assert app("--check", not_formatted) == fail()
         assert app("--enable-formatting", "--check", not_formatted) == fail()
         assert app("--disable-formatting", "--check", not_formatted) == success()
+
+
+def test_config_parameter(app, testfiles):
+    base = testfiles
+    target = base / "directory_with_formatted_files"
+    configuration_file_elsewhere = base / "directory_with_not_formatted_files"
+    configuration_file = configuration_file_elsewhere / ".gersemirc"
+    config = ["--config", configuration_file_elsewhere / ".gersemirc"]
+
+    assert app("--check", target) == success(stderr="")
+    assert app("-l", 100, "--check", target) == fail()
+
+    with create_dot_gersemirc(where=configuration_file_elsewhere, line_length=100):
+        assert app("--check", target) == success(stderr="")
+        assert app("-l", 100, "--check", target) == fail()
+
+        assert app(*config, "--check", target) == fail()
+        assert app(*config, "-l", 80, "--check", target) == success(stderr="")
+
+    with create_dot_gersemirc(
+        where=configuration_file_elsewhere, line_length=100, color=True, kambei=314
+    ):
+        assert app("--check", target) == success(stderr="")
+        assert app("-l", 100, "--check", target) == fail()
+
+        assert app(*config, "--check", target) == fail()
+        assert app(*config, "-l", 80, "--check", target) == success(
+            # pylint: disable=line-too-long
+            stderr=f"""{configuration_file}: these options are supported only through command line: color
+{configuration_file}: these options are not supported: kambei
+"""
+        )