fix(cmd): throw GitCommandNotFoundError ...

... if it is not found. Previously, especially on windows, this wasn't explicit. Fixes#248, affects #126

Author: Byron

doc/source/changes.rst

@@ -12,6 +12,11 @@ Changelog
  these operations to never raise. However, that behavious is undesirable as it would effectively hide the fact that there 
  was an error. See `this issue <https://github.com/gitpython-developers/GitPython/issues/271>`_ for more information.
 
+* If the git executable can't be found in the PATH or at the path provided by `GIT_PYTHON_GIT_EXECUTABLE`, this is made
+ obvious by throwing `GitCommandNotFound`, both on unix and on windows.
+
+ - Those who support **GUI on windows** will now have to set `git.Git.USE_SHELL = True` to get the previous behaviour.
+
 0.3.6 - Features
 ================
 * **DOCS**

git/cmd.py

@@ -26,7 +26,10 @@
 stream_copy,
 WaitGroup
 )
-from .excimportGitCommandError
+from .excimport (
+GitCommandError,
+GitCommandNotFound
+)
 fromgit.compatimport (
 string_types,
 defenc,
@@ -241,6 +244,12 @@ class Git(LazyMixin):
 _git_exec_env_var="GIT_PYTHON_GIT_EXECUTABLE"
 GIT_PYTHON_GIT_EXECUTABLE=os.environ.get(_git_exec_env_var, git_exec_name)
 
+# If True, a shell will be used when executing git commands.
+# This should only be desirable on windows, see https://github.com/gitpython-developers/GitPython/pull/126
+# for more information
+# Override this value using `Git.USE_SHELL = True`
+USE_SHELL=False
+
 classAutoInterrupt(object):
 
 """Kill/Interrupt the stored process instance once this instance goes out of scope. It is
@@ -543,18 +552,29 @@ def execute(self, command,
 env["LC_MESSAGES"] ="C"
 env.update(self._environment)
 
-proc=Popen(command,
-env=env,
-cwd=cwd,
-stdin=istream,
-stderr=PIPE,
-stdout=PIPE,
-# Prevent cmd prompt popups on windows by using a shell ... .
-# See https://github.com/gitpython-developers/GitPython/pull/126
-shell=sys.platform=='win32',
-close_fds=(os.name=='posix'), # unsupported on windows
-**subprocess_kwargs
- )
+ifsys.platform=='win32':
+cmd_not_found_exception=WindowsError
+else:
+ifsys.version_info[0] >2:
+cmd_not_found_exception=FileNotFoundError# NOQA # this is defined, but flake8 doesn't know
+else:
+cmd_not_found_exception=OSError
+# end handle
+
+try:
+proc=Popen(command,
+env=env,
+cwd=cwd,
+stdin=istream,
+stderr=PIPE,
+stdout=PIPE,
+shell=self.USE_SHELL,
+close_fds=(os.name=='posix'), # unsupported on windows
+**subprocess_kwargs
+ )
+exceptcmd_not_found_exceptionaserr:
+raiseGitCommandNotFound(str(err))
+
 ifas_process:
 returnself.AutoInterrupt(proc, command)
 

git/exc.py

@@ -18,6 +18,12 @@ class NoSuchPathError(OSError):
 """ Thrown if a path could not be access by the system. """
 
 
+classGitCommandNotFound(Exception):
+"""Thrown if we cannot find the `git` executable in the PATH or at the path given by
+ the GIT_PYTHON_GIT_EXECUTABLE environment variable"""
+pass
+
+
 classGitCommandError(Exception):
 """ Thrown if execution of the git command fails with non-zero status code. """