Support paging through "more" on windows

This refactors some of the internals to support paging
to "more" on windows.  This is available both in powershell
and in cmd.

awscli/help.py

@@ -1,4 +1,4 @@
-# Copyright 2012-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# Copyright 2012-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License"). You
 # may not use this file except in compliance with the License. A copy of
@@ -10,7 +10,6 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
-import sys
 import logging
 import os
 import platform
@@ -50,82 +49,86 @@ def get_renderer():
         return PosixHelpRenderer()
 
 
-class HelpRenderer(object):
+class PagingHelpRenderer(object):
     """
     Interface for a help renderer.
 
     The renderer is responsible for displaying the help content on
     a particular platform.
+
     """
 
+    PAGER = None
+
+    def get_pager_cmdline(self):
+        pager = self.PAGER
+        if 'MANPAGER' in os.environ:
+            pager = os.environ['MANPAGER']
+        elif 'PAGER' in os.environ:
+            pager = os.environ['PAGER']
+        return shlex.split(pager)
+
     def render(self, contents):
         """
         Each implementation of HelpRenderer must implement this
         render method.
         """
-        pass
+        converted_content = self._convert_doc_content(contents)
+        self._send_output_to_pager(converted_content)
 
+    def _send_output_to_pager(self, output):
+        cmdline = self.get_pager_cmdline()
+        LOG.debug("Running command: %s", cmdline)
+        p = self._popen(cmdline, stdin=PIPE)
+        p.communicate(input=output)
+
+    def _popen(self, *args, **kwargs):
+        return Popen(*args, **kwargs)
 
-class PosixHelpRenderer(HelpRenderer):
+    def _convert_doc_content(self, contents):
+        return contents
+
+
+class PosixHelpRenderer(PagingHelpRenderer):
     """
     Render help content on a Posix-like system.  This includes
     Linux and MacOS X.
     """
 
     PAGER = 'less -R'
 
-    def get_pager_cmdline(self):
-        pager = self.PAGER
-        if 'MANPAGER' in os.environ:
-            pager = os.environ['MANPAGER']
-        elif 'PAGER' in os.environ:
-            pager = os.environ['PAGER']
-        return shlex.split(pager)
-
-    def render(self, contents):
+    def _convert_doc_content(self, contents):
         man_contents = publish_string(contents, writer=manpage.Writer())
         if not self._exists_on_path('groff'):
             raise ExecutableNotFoundError('groff')
         cmdline = ['groff', '-man', '-T', 'ascii']
         LOG.debug("Running command: %s", cmdline)
         p3 = self._popen(cmdline, stdin=PIPE, stdout=PIPE, stderr=PIPE)
         groff_output = p3.communicate(input=man_contents)[0]
-        cmdline = self.get_pager_cmdline()
-        LOG.debug("Running command: %s", cmdline)
-        p4 = self._popen(cmdline, stdin=PIPE)
-        p4.communicate(input=groff_output)
-        sys.exit(1)
+        return groff_output
 
     def _exists_on_path(self, name):
         # Since we're only dealing with POSIX systems, we can
         # ignore things like PATHEXT.
         return any([os.path.exists(os.path.join(p, name))
                     for p in os.environ.get('PATH', '').split(os.pathsep)])
 
-    def _popen(self, *args, **kwargs):
-        return Popen(*args, **kwargs)
 
+class WindowsHelpRenderer(PagingHelpRenderer):
+    """Render help content on a Windows platform."""
 
-class WindowsHelpRenderer(HelpRenderer):
-    """
-    Render help content on a Windows platform.
-    """
+    PAGER = 'more'
 
-    def render(self, contents):
+    def _convert_doc_content(self, contents):
         text_output = publish_string(contents,
                                      writer=TextWriter())
-        sys.stdout.write(text_output.decode('utf-8'))
-        sys.exit(1)
-
-
-class RawRenderer(HelpRenderer):
-    """
-    Render help as the raw ReST document.
-    """
+        return text_output
 
-    def render(self, contents):
-        sys.stdout.write(contents)
-        sys.exit(1)
+    def _popen(self, *args, **kwargs):
+        # Also set the shell value to True.  To get any of the
+        # piping to a pager to work, we need to use shell=True.
+        kwargs['shell'] = True
+        return Popen(*args, **kwargs)
 
 
 class HelpCommand(object):

tests/unit/customizations/test_cloudsearchdomain.py

@@ -12,7 +12,7 @@
 # language governing permissions and limitations under the License.
 from awscli.testutils import unittest
 from awscli.testutils import BaseAWSCommandParamsTest
-from awscli.help import HelpRenderer
+from awscli.help import PagingHelpRenderer
 from awscli.customizations.cloudsearchdomain import validate_endpoint_url
 
 import mock
@@ -46,7 +46,7 @@ def test_endpoint_is_required(self):
     def test_endpoint_not_required_for_help(self):
         cmd = self.prefix + 'help'
         with mock.patch('awscli.help.get_renderer') as get_renderer:
-            mock_render = mock.Mock(spec=HelpRenderer)
+            mock_render = mock.Mock(spec=PagingHelpRenderer)
             get_renderer.return_value = mock_render
             stdout, stderr, rc = self.run_cmd(cmd, expected_rc=None)
             # If we get this far we've succeeded, but we can do

tests/unit/test_help.py

@@ -17,19 +17,29 @@
 import mock
 
 from awscli.help import PosixHelpRenderer, ExecutableNotFoundError
+from awscli.help import WindowsHelpRenderer
 
 
-class FakePosixHelpRenderer(PosixHelpRenderer):
+class HelpSpyMixin(object):
     def __init__(self):
         self.exists_on_path = {}
         self.popen_calls = []
+        self.mock_popen = mock.Mock()
 
     def _exists_on_path(self, name):
         return self.exists_on_path.get(name)
 
     def _popen(self, *args, **kwargs):
         self.popen_calls.append((args, kwargs))
-        return mock.Mock()
+        return self.mock_popen
+
+
+class FakePosixHelpRenderer(HelpSpyMixin, PosixHelpRenderer):
+    pass
+
+
+class FakeWindowsHelpRenderer(HelpSpyMixin, WindowsHelpRenderer):
+    pass
 
 
 class TestHelpPager(unittest.TestCase):
@@ -78,10 +88,8 @@ def test_pager_with_args(self):
                          pager_cmd.split())
 
     @unittest.skipIf(sys.platform.startswith('win'), "requires posix system")
-    @mock.patch('sys.exit', mock.Mock())
     def test_no_groff_exists(self):
         renderer = FakePosixHelpRenderer()
-        # Simulate neither rst2man.py nor rst2man existing on the path.
         renderer.exists_on_path['groff'] = False
         with self.assertRaisesRegexp(ExecutableNotFoundError,
                                      'Could not find executable named "groff"'):
@@ -92,3 +100,16 @@ def test_shlex_split_for_pager_var(self):
         os.environ['PAGER'] = pager_cmd
         self.assertEqual(self.renderer.get_pager_cmdline(),
                          ['/bin/sh', '-c', "col -bx | vim -c 'set ft=man' -"])
+
+    def test_can_render_contents(self):
+        renderer = FakePosixHelpRenderer()
+        renderer.exists_on_path['groff'] = True
+        renderer.mock_popen.communicate.return_value = ('rendered', '')
+        renderer.render('foo')
+        self.assertEqual(renderer.popen_calls[-1][0], (['less', '-R'],))
+
+    def test_can_page_output_on_windows(self):
+        renderer = FakeWindowsHelpRenderer()
+        renderer.mock_popen.communicate.return_value = ('rendered', '')
+        renderer.render('foo')
+        self.assertEqual(renderer.popen_calls[-1][0], (['more'],))