Merge pull request #44 from mesosphere/refactor-cmd-execution

Refactor cmd execution

dcos/api/cmds.py

@@ -0,0 +1,49 @@
+import collections
+
+from dcos.api import errors
+
+Command = collections.namedtuple(
+    'Command',
+    ['hierarchy', 'arg_keys', 'function'])
+"""Describe a CLI command.
+
+:param hierarchy: the noun and verbs that need to be set for the command to
+                  execute
+:type hierarchy: list of str
+:param arg_keys: the arguments that must get passed to the function; the order
+                 of the keys determines the order in which they get passed to
+                 the function
+:type arg_keys: list of str
+:param function: the function to execute
+:type function: func(args) -> int
+"""
+
+
+def execute(cmds, args):
+    """Executes one of the commands based on the arguments passed.
+
+    :param cmds: commands to try to execute; the order determines the order of
+                 evaluation
+    :type cmds: list of Command
+    :param args: command line arguments
+    :type args: dict
+    :returns: the process status
+    :rtype: (int, dcos.errors.Error)
+    """
+
+    for hierarchy, arg_keys, function in cmds:
+        # Let's find if the function matches the command
+        match = True
+        for positional in hierarchy:
+            if not args[positional]:
+                match = False
+
+        if match:
+            params = [args[name] for name in arg_keys]
+            return (function(*params), None)
+
+    return (
+        None,
+        errors.DefaultError(
+            'Could not find a command with the passed arguments')
+    )

dcos/cli/app/main.py

@@ -41,8 +41,8 @@ import sys
 
 import docopt
 import pkg_resources
-from dcos.api import (config, constants, emitting, errors, jsonitem, marathon,
-                      options, util)
+from dcos.api import (cmds, config, constants, emitting, errors, jsonitem,
+                      marathon, options, util)
 
 logger = util.get_logger(__name__)
 emitter = emitting.FlatEmitter()
@@ -62,39 +62,63 @@ def main():
         emitter.publish(options.make_generic_usage_error(__doc__))
         return 1
 
-    if args['info']:
-        return _info()
+    returncode, err = cmds.execute(_cmds(), args)
+    if err is not None:
+        emitter.publish(err)
+        emitter.publish(options.make_generic_usage_error(__doc__))
+        return 1
 
-    if args['add']:
-        return _add()
+    return returncode
 
-    if args['version'] and args['list']:
-        return _version_list(args['<app-id>'], args['--max-count'])
 
-    if args['list']:
-        return _list()
+def _cmds():
+    """
+    :returns: all the supported commands
+    :rtype: dcos.api.cmds.Command
+    """
 
-    if args['remove']:
-        return _remove(args['<app-id>'], args['--force'])
+    return [
+        cmds.Command(hierarchy=['info'], arg_keys=[], function=_info),
 
-    if args['show']:
-        return _show(args['<app-id>'], args['--app-version'])
+        cmds.Command(hierarchy=['add'], arg_keys=[], function=_add),
 
-    if args['start']:
-        return _start(args['<app-id>'], args['<instances>'], args['--force'])
+        cmds.Command(
+            hierarchy=['version', 'list'],
+            arg_keys=['<app-id>', '--max-count'],
+            function=_version_list),
 
-    if args['stop']:
-        return _stop(args['<app-id>'], args['--force'])
+        cmds.Command(hierarchy=['list'], arg_keys=[], function=_list),
 
-    if args['update']:
-        return _update(args['<app-id>'], args['<properties>'], args['--force'])
+        cmds.Command(
+            hierarchy=['remove'],
+            arg_keys=['<app-id>', '--force'],
+            function=_remove),
 
-    if args['restart']:
-        return _restart(args['<app-id>'], args['--force'])
+        cmds.Command(
+            hierarchy=['show'],
+            arg_keys=['<app-id>', '--app-version'],
+            function=_show),
 
-    emitter.publish(options.make_generic_usage_error(__doc__))
+        cmds.Command(
+            hierarchy=['start'],
+            arg_keys=['<app-id>', '<instances>', '--force'],
+            function=_start),
 
-    return 1
+        cmds.Command(
+            hierarchy=['stop'],
+            arg_keys=['<app-id>', '--force'],
+            function=_stop),
+
+        cmds.Command(
+            hierarchy=['update'],
+            arg_keys=['<app-id>', '<properties>', '--force'],
+            function=_update),
+
+        cmds.Command(
+            hierarchy=['restart'],
+            arg_keys=['<app-id>', '--force'],
+            function=_restart),
+    ]
 
 
 def _info():

pydoc/modules.rst

@@ -1,6 +1,15 @@
 API Documentation
 =================
 
+The :mod:`dcos.api.cmds` Module
+---------------------------------
+
+.. automodule:: dcos.api.cmds
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:
+
 The :mod:`dcos.api.config` Module
 ---------------------------------
 

tests/test_cmds.py

@@ -0,0 +1,100 @@
+import pytest
+from dcos.api import cmds, errors
+
+
+@pytest.fixture
+def args():
+    return {
+        'cmd-a': True,
+        'cmd-b': True,
+        'cmd-c': False,
+        'arg-1': 'arg-1',
+        'arg-2': 'arg-2',
+        'arg-0': 'arg-0',
+    }
+
+
+def test_single_cmd(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-a', 'cmd-b'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=function),
+    ]
+
+    assert cmds.execute(commands, args) == (1, None)
+
+
+def test_multiple_cmd(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-c'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=pytest.fail),
+        cmds.Command(
+            hierarchy=['cmd-a', 'cmd-b'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=function),
+    ]
+
+    assert cmds.execute(commands, args) == (1, None)
+
+
+def test_no_matching_cmd(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-c'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=pytest.fail),
+    ]
+
+    returncode, err = cmds.execute(commands, args)
+
+    assert returncode is None
+    assert isinstance(err, errors.Error)
+
+
+def test_similar_cmds(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-a', 'cmd-b'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=function),
+        cmds.Command(
+            hierarchy=['cmd-a'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=pytest.fail),
+    ]
+
+    assert cmds.execute(commands, args) == (1, None)
+
+
+def test_missing_cmd(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-d'],
+            arg_keys=['arg-0', 'arg-1', 'arg-2'],
+            function=pytest.fail),
+    ]
+
+    with pytest.raises(KeyError):
+        returncode, err = cmds.execute(commands, args)
+
+
+def test_missing_arg(args):
+    commands = [
+        cmds.Command(
+            hierarchy=['cmd-a'],
+            arg_keys=['arg-3'],
+            function=pytest.fail),
+    ]
+
+    with pytest.raises(KeyError):
+        returncode, err = cmds.execute(commands, args)
+
+
+def function(*args):
+    for i in range(len(args)):
+        assert args[i] == 'arg-{}'.format(i)
+
+    return 1