Normalize the command earlier so we can output exactly what we run.

src/sphinxcontrib/programoutput/__init__.py

@@ -133,17 +133,38 @@ class Command(_Command):
 
     def __new__(cls, command, shell=False, hide_standard_error=False,
                 working_directory='/'):
-        if isinstance(command, list):
-            command = tuple(command)
         # `chdir()` resolves symlinks, so we need to resolve them too for
         # caching to make sure that different symlinks to the same directory
         # don't result in different cache keys.  Also normalize paths to make
         # sure that identical paths are also equal as strings.
         working_directory = os.path.normpath(os.path.realpath(
             working_directory))
+        # Likewise, normalize the command now for better caching, and so
+        # that we can present *exactly* what we run to the user.
+        command = cls.__normalize_command(command, shell)
         return _Command.__new__(cls, command, shell, hide_standard_error,
                                 working_directory)
 
+    @staticmethod
+    def __normalize_command(command, shell):
+        # Returns either a native string, to a tuple.
+        if (bytes is str
+                and not isinstance(command, str)
+                and hasattr(command, 'encode')):
+            # Python 2, given a unicode string
+            command = command.encode(sys.getfilesystemencoding())
+            assert isinstance(command, str)
+
+        if not shell and isinstance(command, str):
+            command = shlex.split(command)
+
+        if isinstance(command, list):
+            command = tuple(command)
+
+        assert isinstance(command, (str, tuple)), command
+
+        return command
+
     @classmethod
     def from_program_output_node(cls, node):
         """
@@ -162,18 +183,7 @@ def execute(self):
         command.
         """
         command = self.command
-        if (bytes is str
-                and not isinstance(command, str)
-                and hasattr(command, 'encode')):
-            # Python 2, given a unicode string
-            command = command.encode(sys.getfilesystemencoding())
-            assert isinstance(command, str)
 
-        if not self.shell:
-            if isinstance(command, str):
-                command = shlex.split(command)
-            else:
-                command = self.command
 
         return Popen(command, shell=self.shell, stdout=PIPE,
                      stderr=PIPE if self.hide_standard_error else STDOUT,

src/sphinxcontrib/programoutput/tests/test_command.py

@@ -37,7 +37,8 @@ class TestCommand(unittest.TestCase):
 
     def test_new_with_string_command(self):
         cmd = 'echo "spam with eggs"'
-        self.assertEqual(Command(cmd).command, cmd)
+        parsed_cmd = ('echo', 'spam with eggs')
+        self.assertEqual(Command(cmd).command, parsed_cmd)
         self.assertEqual(Command(cmd, shell=True).command, cmd)
 
 
@@ -59,7 +60,8 @@ def test_from_programoutput_node(self):
         node['hide_standard_error'] = False
         node['working_directory'] = '/spam/with/eggs'
         command = Command.from_program_output_node(node)
-        self.assertEqual(command.command, 'echo spam')
+        parsed_command = ('echo', 'spam')
+        self.assertEqual(command.command, parsed_command)
         self.assertEqual(command.working_directory, '/spam/with/eggs')
         self.assertFalse(command.shell)
         self.assertFalse(command.hide_standard_error)
@@ -78,7 +80,8 @@ def test_from_programoutput_node_extraargs(self):
         node['extraargs'] = 'with eggs'
         node['working_directory'] = '/'
         command = Command.from_program_output_node(node)
-        self.assertEqual(command.command, 'echo spam with eggs')
+        parsed_command = ('echo', 'spam', 'with', 'eggs')
+        self.assertEqual(command.command, parsed_command)
 
 
     def test_execute(self, **kwargs):

src/sphinxcontrib/programoutput/tests/test_directive.py

@@ -292,7 +292,8 @@ def test_unexpected_return_code(self):
             self.app.build()
         self.assertIn('Unexpected return code 1 from command',
                       excinfo.exception.args[0])
-        self.assertIn(sys.executable + " -c 'import sys; sys.exit(1)'",
+        parsed_command = (sys.executable, '-c', 'import sys; sys.exit(1)')
+        self.assertIn(repr(parsed_command),
                       excinfo.exception.args[0])