Add root application command module

fimfarchive/commands/__init__.py

@@ -23,8 +23,10 @@ Command module.
 
 
 from .base import Command
+from .root import RootCommand
 
 
 __all__ = (
     'Command',
+    'RootCommand',
 )

fimfarchive/commands/root.py

@@ -0,0 +1,112 @@
+"""
+Root command.
+"""
+
+
+#
+# Fimfarchive, preserves stories from Fimfiction.
+# Copyright (C) 2015  Joakim Soderlund
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# 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 typing import Dict, Type
+
+from .base import Command
+
+
+__all__ = (
+    'RootCommand',
+)
+
+
+class RootCommand(Command):
+    """
+    The main application command.
+    """
+    commands: Dict[str, Type[Command]] = dict()
+
+    def load(self, command: str) -> Command:
+        """
+        Instantiates a command.
+
+        Args:
+            command: Name of the command to instantiate.
+
+        Returns:
+            An instance of the specified command.
+
+        Raises:
+            KeyError: If the command does not exist.
+        """
+        return self.commands[command]()
+
+    def doc(self, command: str, adjust=1, indent=2) -> str:
+        """
+        Generates documentation for a single command.
+
+        Args:
+            command: Name of the command to document.
+            adjust: Number of spaces before the command summary.
+            indent: Number of spaces before the command name.
+
+        Returns:
+            A name and summary for the command.
+        """
+        cls = self.load(command)
+        doc = getattr(cls, '__doc__', None)
+
+        if doc:
+            doc = str(doc).strip()
+            doc = doc.split('\n', 1)[0]
+
+        description = [
+            indent * ' ',
+            command.ljust(adjust),
+            str(doc),
+        ]
+
+        return ''.join(description)
+
+    @property
+    def usage(self) -> str:
+        """
+        Generates a list of the available commands.
+
+        Returns:
+            A usage help text for the application.
+        """
+        text = [
+            'Usage: COMMAND [PARAMETERS]\n\n',
+            'Fimfarchive, ensuring that history is preseved.\n\n',
+        ]
+
+        commands = sorted(cmd for cmd in self.commands.keys())
+        adjust = max(len(cmd) for cmd in commands) + 2
+
+        text.append('Commands:\n')
+        for command in commands:
+            line = self.doc(command, adjust)
+            text.extend((line, '\n'))
+
+        return ''.join(text).strip()
+
+    def __call__(self, *args: str) -> int:
+        try:
+            cmd = self.load(args[0])
+        except (IndexError, KeyError):
+            exit(self.usage)
+        else:
+            return cmd(*args[1:])

tests/commands/test_root.py

@@ -0,0 +1,193 @@
+"""
+Root command tests.
+"""
+
+
+#
+# Fimfarchive, preserves stories from Fimfiction.
+# Copyright (C) 2015  Joakim Soderlund
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# 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 unittest.mock import MagicMock, PropertyMock
+
+import pytest
+
+from fimfarchive.commands import Command, RootCommand
+
+
+@pytest.fixture
+def success():
+    """
+    Returns a command that succeeds.
+    """
+    class cls(Command):
+        """
+        Command that returns 0.
+
+        With a truncated documentation line.
+        """
+        __call__ = MagicMock(return_value=0)
+
+    return cls()
+
+
+@pytest.fixture
+def failure():
+    """
+    Returns a command that fails.
+    """
+    class cls(Command):
+        """
+        Command that returns 1.
+
+        With a truncated documentation line.
+        """
+        __call__ = MagicMock(return_value=1)
+
+    return cls()
+
+
+@pytest.fixture
+def root(success, failure):
+    """
+    Returns a root command with custom subcommands.
+    """
+    class cls(RootCommand):
+        """
+        Custom root command.
+        """
+        commands = {
+            'success': type(success),
+            'failure': type(failure),
+        }
+
+    return cls()
+
+
+@pytest.fixture
+def args():
+    """
+    Returns random command line arguments.
+    """
+    return [object() for i in range(3)]
+
+
+class TestRootCommanad():
+    """
+    Tests the root command.
+    """
+
+    def mock_usage(self, cmd):
+        """
+        Returns a mocked usage property for the command.
+        """
+        usage = PropertyMock()
+        type(cmd).usage = usage
+        return usage
+
+    def test_root_usage(self, root):
+        """
+        Tests usage contains first line of class documentation.
+        """
+        doc = root.usage
+        assert "success  Command that returns 0." in doc
+        assert "failure  Command that returns 1." in doc
+        assert "truncated documentation line" not in doc
+
+    def test_root_call_without_args(self, root, success, failure):
+        """
+        Tests `SystemExit` is raised if called without arguments.
+        """
+        usage = self.mock_usage(root)
+
+        with pytest.raises(SystemExit):
+            root()
+
+        usage.assert_called_once_with()
+        success.__call__.assert_not_called()
+        failure.__call__.assert_not_called()
+
+    def test_root_call_with_args(self, root, success, failure, args):
+        """
+        Tests `SystemExit` is raised if called with invalid arguments.
+        """
+        usage = self.mock_usage(root)
+
+        with pytest.raises(SystemExit):
+            root(*args)
+
+        usage.assert_called_once_with()
+        success.__call__.assert_not_called()
+        failure.__call__.assert_not_called()
+
+    def test_success_usage(self, root):
+        """
+        Tests success usage contains first line of class documentation.
+        """
+        doc = root.doc('success', adjust=9, indent=0)
+        assert "success  Command that returns 0." == doc
+
+    def test_success_call_without_args(self, root, success, failure):
+        """
+        Tests success can be called without arguments.
+        """
+        usage = self.mock_usage(root)
+        code = root('success')
+        success.__call__.assert_called_once_with()
+        failure.__call__.assert_not_called()
+        usage.assert_not_called()
+        assert code == 0
+
+    def test_success_call_with_args(self, root, success, failure, args):
+        """
+        Tests success can be called with arguments.
+        """
+        usage = self.mock_usage(root)
+        code = root('success', *args)
+        success.__call__.assert_called_once_with(*args)
+        failure.__call__.assert_not_called()
+        usage.assert_not_called()
+        assert code == 0
+
+    def test_failure_usage(self, root):
+        """
+        Tests failure usage contains first line of class documentation.
+        """
+        doc = root.doc('failure', adjust=9, indent=0)
+        assert "failure  Command that returns 1." == doc
+
+    def test_failure_call_without_args(self, root, success, failure):
+        """
+        Tests failure can be called without arguments.
+        """
+        usage = self.mock_usage(root)
+        code = root('failure')
+        success.__call__.assert_not_called()
+        failure.__call__.assert_called_once_with()
+        usage.assert_not_called()
+        assert code == 1
+
+    def test_failure_call_with_args(self, root, success, failure, args):
+        """
+        Tests failure can be called with arguments.
+        """
+        usage = self.mock_usage(root)
+        code = root('failure', *args)
+        success.__call__.assert_not_called()
+        failure.__call__.assert_called_once_with(*args)
+        usage.assert_not_called()
+        assert code == 1