Split init / exec of tmux_cmd for debuggability

tmux_cmd initialization composes the command

the command will be available in the instance attribute
.cmd

.execute() instance method will run tmux_cmd

see Server.cmd for example of new usage

Related #77

libtmux/common.py

@@ -141,7 +141,12 @@ class tmux_cmd(object):
 
     Usage::
 
-        proc = tmux_cmd('new-session', '-s%' % 'my session')
+        c = tmux_cmd('new-session', '-s%' % 'my session')
+
+        # You can actually see the command in the .cmd attribute
+        print(c.cmd)
+
+        proc = c.execute()
 
         if proc.stderr:
             raise exc.LibTmuxException(
@@ -178,6 +183,8 @@ def __init__(self, *args, **kwargs):
 
         self.cmd = cmd
 
+    def execute(self):
+        cmd = self.cmd
         try:
             self.process = subprocess.Popen(
                 cmd,
@@ -213,6 +220,7 @@ def __init__(self, *args, **kwargs):
             'self.stdout for %s: \n%s' %
             (' '.join(cmd), self.stdout)
         )
+        return self
 
 
 class TmuxMappingObject(collections.MutableMapping):
@@ -260,7 +268,7 @@ def __len__(self):
     def __getattr__(self, key):
         try:
             return self._info[self.formatter_prefix + key]
-        except:
+        except KeyError:
             raise AttributeError('%s has no property %s' %
                                  (self.__class__, key))
 
@@ -354,8 +362,8 @@ def get_by_id(self, id):
 
 
 def which(exe=None, default_paths=[
-            '/bin', '/sbin', '/usr/bin', '/usr/sbin', '/usr/local/bin'
-        ], append_env_path=True):
+          '/bin', '/sbin', '/usr/bin', '/usr/sbin', '/usr/local/bin'
+          ], append_env_path=True):
     """Return path of bin. Python clone of /usr/bin/which.
 
     from salt.util - https://www.github.com/saltstack/salt - license apache
@@ -413,7 +421,7 @@ def get_version():
     :returns: tmux version
     :rtype: :class:`distutils.version.LooseVersion`
     """
-    proc = tmux_cmd('-V')
+    proc = tmux_cmd('-V').execute()
     if proc.stderr:
         if proc.stderr[0] == 'tmux: unknown option -- V':
             if sys.platform.startswith("openbsd"):  # openbsd has no tmux -V

libtmux/server.py

@@ -96,7 +96,7 @@ def cmd(self, *args, **kwargs):
             else:
                 raise ValueError('Server.colors must equal 88 or 256')
 
-        return tmux_cmd(*args, **kwargs)
+        return tmux_cmd(*args, **kwargs).execute()
 
     def _list_sessions(self):
         """Return list of sessions in :py:obj:`dict` form.

tests/test_common.py

@@ -25,6 +25,9 @@ def mock_tmux_cmd(param):
         class Hi(object):
             stdout = ['tmux master']
             stderr = None
+
+            def execute(self):
+                return self
         return Hi()
     monkeypatch.setattr(libtmux.common, 'tmux_cmd', mock_tmux_cmd)
 
@@ -42,6 +45,9 @@ def test_get_version_openbsd(monkeypatch):
     def mock_tmux_cmd(param):
         class Hi(object):
             stderr = ['tmux: unknown option -- V']
+
+            def execute(self):
+                return self
         return Hi()
     monkeypatch.setattr(libtmux.common, 'tmux_cmd', mock_tmux_cmd)
     monkeypatch.setattr(sys, 'platform', 'openbsd 5.2')
@@ -59,6 +65,9 @@ def test_get_version_too_low(monkeypatch):
     def mock_tmux_cmd(param):
         class Hi(object):
             stderr = ['tmux: unknown option -- V']
+
+            def execute(self):
+                return self
         return Hi()
     monkeypatch.setattr(libtmux.common, 'tmux_cmd', mock_tmux_cmd)
     with pytest.raises(LibTmuxException) as exc_info:
@@ -153,6 +162,12 @@ def test_tmux_cmd_raises_on_not_found():
     tmux_cmd('-V')
 
 
+def test_tmux_cmd_makes_cmd_available():
+    """tmux_cmd objects should make .cmd attribute available."""
+    command = tmux_cmd('-V')
+    assert hasattr(command, 'cmd')
+
+
 @pytest.mark.parametrize("session_name,raises,exc_msg_regex", [
     ('', True, 'may not be empty'),
     (None, True, 'may not be empty'),