Introduce support for mocking command output

This change rewrites FakePopen to permit registering commands and
synthetic output such that client code can call subprocess.Popen() and
receive required output without actually executing commands.

With this change, it is possible to mock most of the output
require during a packstack run.

Change-Id: If81f71cfe89a61e25fb62c97ed5b3759039a0bfb

tests/installer/test_run_setup.py

@@ -23,6 +23,7 @@ from unittest import TestCase
 
 from packstack.modules import ospluginutils, puppet
 from packstack.installer import run_setup, basedefs
+from packstack.installer.utils import shell
 
 from ..test_base import PackstackTestCaseMixin, FakePopen
 
@@ -45,9 +46,15 @@ class CommandLineTestCase(PackstackTestCaseMixin, TestCase):
         """
         # we need following to pass manage_epel(enabled=1) and
         # manage_rdo(havana-6.noarch\nenabled=0) functions
-        fake = FakePopen()
-        fake.stdout = 'havana-6.noarch\nenabled=0enabled=1'
-        subprocess.Popen = fake
+        subprocess.Popen = FakePopen
+        FakePopen.register('cat /etc/resolv.conf | grep nameserver',
+                           stdout='nameserver 127.0.0.1')
+        FakePopen.register("rpm -q rdo-release "
+                           "--qf='%{version}-%{release}.%{arch}\n'",
+                           stdout='icehouse-2.noarch\n')
+        FakePopen.register_as_script('yum-config-manager --enable '
+                                     'openstack-icehouse',
+                                     stdout='[openstack-icehouse]\nenabled=1')
 
         # create a dummy public key
         dummy_public_key = os.path.join(self.tempdir, 'id_rsa.pub')
@@ -56,7 +63,8 @@ class CommandLineTestCase(PackstackTestCaseMixin, TestCase):
 
         # Save sys.argv and replace it with the args we want optparse to use
         orig_argv = sys.argv
-        sys.argv = ['packstack', '--ssh-public-key=%s' % dummy_public_key,
+        sys.argv = ['packstack', '--debug',
+                    '--ssh-public-key=%s' % dummy_public_key,
                     '--install-hosts=127.0.0.1', '--os-swift-install=y',
                     '--nagios-install=y', '--use-epel=y']
 

tests/installer/test_utils.py

@@ -23,7 +23,7 @@ import shutil
 import tempfile
 from unittest import TestCase
 
-from ..test_base import PackstackTestCaseMixin
+from ..test_base import PackstackTestCaseMixin, FakePopen
 from packstack.installer.utils import *
 from packstack.installer.utils.strings import STR_MASK
 from packstack.installer.exceptions import ExecuteRuntimeError
@@ -36,6 +36,8 @@ class ParameterTestCase(PackstackTestCaseMixin, TestCase):
     def setUp(self):
         # Creating a temp directory that can be used by tests
         self.tempdir = tempfile.mkdtemp()
+        FakePopen.register('echo "this is test"',
+                           stdout='this is test')
 
     def tearDown(self):
         # remove the temp directory

tests/test_base.py

@@ -18,20 +18,87 @@
 import shutil
 import tempfile
 import subprocess
+import logging
+import re
+
+from packstack.installer.utils.shell import block_fmt
+from packstack.installer.exceptions import (ScriptRuntimeError,
+                                            NetworkError)
+from packstack.installer.utils.strings import mask_string
+
+LOG = logging.getLogger(__name__)
 
 
 class FakePopen(object):
-    def __init__(self, returncode=0):
-        self.returncode = returncode
-        self.stdout = self.stderr = self.data = ""
+    '''The FakePopen class replaces subprocess.Popen. Instead of actually
+    executing commands, it permits the caller to register a list of
+    commands the output to produce using the FakePopen.register and
+    FakePopen.register_as_script method.  By default, FakePopen will return
+    empty stdout and stderr and a successful (0) returncode.
+    '''
 
-    def __call__(self, *args, **kwargs):
-        self.args = args
-        self.kwargs = kwargs
-        return self
+    cmd_registry = {}
+    script_registry = {}
 
-    def communicate(self, data=None):
-        self.data += data or ''
+    @classmethod
+    def register(cls, args, stdout='', stderr='', returncode=0):
+        '''Register a fake command.'''
+        if isinstance(args, list):
+            args = tuple(args)
+        cls.cmd_registry[args] = {'stdout': stdout,
+                                  'stderr': stderr,
+                                  'returncode': returncode}
+
+    @classmethod
+    def register_as_script(cls, args, stdout='', stderr='', returncode=0):
+        '''Register a fake script.'''
+        if isinstance(args, list):
+            args = '\n'.join(args)
+        prefix = "function t(){ exit $? ; } \n trap t ERR \n"
+        args = prefix + args
+        cls.script_registry[args] = {'stdout': stdout,
+                                     'stderr': stderr,
+                                     'returncode': returncode}
+
+    def __init__(self, args, **kwargs):
+        script = ["ssh", "-o", "StrictHostKeyChecking=no",
+                  "-o", "UserKnownHostsFile=/dev/null"]
+        if args[-1] == "bash -x" and args[:5] == script:
+            self._init_as_script(args, **kwargs)
+        else:
+            self._init_as_cmd(args, **kwargs)
+
+    def _init_as_cmd(self, args, **kwargs):
+        self._is_script = False
+        if isinstance(args, list):
+            args = tuple(args)
+            cmd = ' '.join(args)
+        else:
+            cmd = args
+
+        if args in self.cmd_registry:
+            this = self.cmd_registry[args]
+        else:
+            LOG.warn('call to unregistered command: %s', cmd)
+            this = {'stdout': '', 'stderr': '', 'returncode': 0}
+
+        self.stdout = this['stdout']
+        self.stderr = this['stderr']
+        self.returncode = this['returncode']
+
+    def _init_as_script(self, args, **kwargs):
+        self._is_script = True
+
+    def communicate(self, input=None):
+        if self._is_script:
+            if input in self.script_registry:
+                this = self.script_registry[input]
+            else:
+                LOG.warn('call to unregistered script: %s', input)
+                this = {'stdout': '', 'stderr': '', 'returncode': 0}
+            self.stdout = this['stdout']
+            self.stderr = this['stderr']
+            self.returncode = this['returncode']
         return self.stdout, self.stderr
 
 
@@ -46,7 +113,7 @@ class PackstackTestCaseMixin(object):
 
         # some plugins call popen, we're replacing it for tests
         self._Popen = subprocess.Popen
-        self.fake_popen = subprocess.Popen = FakePopen()
+        self.fake_popen = subprocess.Popen = FakePopen
 
     def tearDown(self):
         # remove the temp directory