Add: Introduce new dataclass for storing the autohooks settings

The settigs contain the mode and the list of activated plugin modules.
The class allows to write the mode and plugins to a toml file like the
pyproject.toml.

autohooks/settings.py

@@ -15,7 +15,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from dataclasses import dataclass, field
 from enum import Enum
+from pathlib import Path
+from typing import Iterable
+
+import tomlkit
 
 
 class Mode(Enum):
@@ -51,3 +56,35 @@ def from_string(modestring: str) -> "Mode":
 
     def __str__(self) -> str:
         return self.name.lower()  # pylint: disable=no-member
+
+
+@dataclass
+class AutohooksSettings:
+    mode: Mode = Mode.UNDEFINED
+    pre_commit: Iterable[str] = field(default_factory=list)
+
+    def write(self, filename: Path) -> None:
+        """
+        Write the current AutohooksSettings to a TOML file
+
+        If the TOML file already exists only the [tool.autohooks] section is
+        overridden.
+        """
+        if filename.exists():
+            toml_doc = tomlkit.loads(filename.read_text())
+        else:
+            toml_doc = tomlkit.document()
+
+        if "tool" not in toml_doc:
+            toml_doc["tool"] = tomlkit.table(is_super_table=True)
+        if "autohooks" not in toml_doc["tool"]:
+            toml_doc["tool"]["autohooks"] = tomlkit.table()
+
+        config_dict = {
+            "mode": str(self.mode.get_effective_mode()),
+            "pre-commit": self.pre_commit,
+        }
+
+        toml_doc["tool"]["autohooks"].update(config_dict)
+
+        filename.write_text(tomlkit.dumps(toml_doc), encoding="utf8")

tests/test_settings.py

@@ -15,9 +15,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# pylint: disable=invalid-name
+
 import unittest
 
-from autohooks.settings import Mode
+from autohooks.settings import AutohooksSettings, Mode
+from tests import tempdir, testfile
 
 
 class ModeTestCase(unittest.TestCase):
@@ -77,5 +80,84 @@ def test_string_conversion(self):
         self.assertEqual(str(Mode.UNDEFINED), "undefined")
 
 
+pyproject_toml_1 = """
+[tool.autohooks]
+pre-commit = ['foo', 'bar']
+plugins.foo.bar = 'ipsum'
+plugins.foo.lorem = 'dolor'
+
+[tool.autohooks.plugins.bar]
+foo = 'bar'
+"""
+
+
+class AutohooksSettingsTestCase(unittest.TestCase):
+    def test_create_empty(self):
+        settings = AutohooksSettings()
+        self.assertEqual(settings.mode, Mode.UNDEFINED)
+        self.assertEqual(settings.pre_commit, [])
+
+    def test_create(self):
+        settings = AutohooksSettings(mode=Mode.POETRY, pre_commit=["a", "b"])
+
+        self.assertEqual(settings.mode, Mode.POETRY)
+        self.assertEqual(settings.pre_commit, ["a", "b"])
+
+    def test_save_settings_new_empty(self):
+        settings = AutohooksSettings()
+        expected = """[tool.autohooks]
+mode = "pythonpath"
+pre-commit = []
+"""
+        with tempdir() as tmp_path:
+            toml = tmp_path / "test.toml"
+            settings.write(toml)
+
+            self.assertEqual(settings.mode, Mode.UNDEFINED)
+            self.assertEqual(settings.pre_commit, [])
+
+            self.assertEqual(toml.read_text(encoding="utf8"), expected)
+
+    def test_save_empty_override(self):
+        settings = AutohooksSettings()
+        expected = """
+[tool.autohooks]
+pre-commit = []
+mode = "pythonpath"
+plugins.foo.bar = 'ipsum'
+plugins.foo.lorem = 'dolor'
+
+[tool.autohooks.plugins.bar]
+foo = 'bar'
+"""
+        with testfile(pyproject_toml_1) as toml:
+            settings.write(toml)
+
+            self.assertEqual(settings.mode, Mode.UNDEFINED)
+            self.assertEqual(settings.pre_commit, [])
+
+            self.assertEqual(toml.read_text(encoding="utf8"), expected)
+
+    def test_save_override(self):
+        settings = AutohooksSettings(mode=Mode.POETRY, pre_commit=["a", "b"])
+        expected = """
+[tool.autohooks]
+pre-commit = ["a", "b"]
+mode = "poetry"
+plugins.foo.bar = 'ipsum'
+plugins.foo.lorem = 'dolor'
+
+[tool.autohooks.plugins.bar]
+foo = 'bar'
+"""
+        with testfile(pyproject_toml_1) as toml:
+            settings.write(toml)
+
+            self.assertEqual(settings.mode, Mode.POETRY)
+            self.assertEqual(settings.pre_commit, ["a", "b"])
+
+            self.assertEqual(toml.read_text(encoding="utf8"), expected)
+
+
 if __name__ == "__main__":
     unittest.main()