Make no_command work only when apt available

tests/rules/test_no_command_apt.py

@@ -1,7 +1,7 @@
 from subprocess import PIPE
 from mock import patch, Mock
 import pytest
-from thefuck.rules.no_command import match, get_new_command
+from thefuck.rules.no_command_apt import match, get_new_command
 from thefuck.main import Command
 
 
@@ -19,8 +19,17 @@ vom: command not found
 '''
 
 
+@pytest.fixture
+def bins_exists(request):
+    p = patch('thefuck.rules.no_command_apt.which',
+              return_value=True)
+    p.start()
+    request.addfinalizer(p.stop)
+
+
+@pytest.mark.usefixtures('bins_exists')
 def test_match(command_found, command_not_found):
-    with patch('thefuck.rules.no_command.Popen') as Popen:
+    with patch('thefuck.rules.no_command_apt.Popen') as Popen:
         Popen.return_value.stderr.read.return_value = command_found
         assert match(Command('aptget install vim', '', ''), None)
         Popen.assert_called_once_with('/usr/lib/command-not-found aptget',
@@ -28,7 +37,7 @@ def test_match(command_found, command_not_found):
         Popen.return_value.stderr.read.return_value = command_not_found
         assert not match(Command('ls', '', ''), None)
 
-    with patch('thefuck.rules.no_command.Popen') as Popen:
+    with patch('thefuck.rules.no_command_apt.Popen') as Popen:
         Popen.return_value.stderr.read.return_value = command_found
         assert match(Command('sudo aptget install vim', '', ''),
                      Mock(command_not_found='test'))
@@ -36,8 +45,9 @@ def test_match(command_found, command_not_found):
                                       shell=True, stderr=PIPE)
 
 
+@pytest.mark.usefixtures('bins_exists')
 def test_get_new_command(command_found):
-    with patch('thefuck.rules.no_command._get_output',
+    with patch('thefuck.rules.no_command_apt._get_output',
                return_value=command_found.decode()):
         assert get_new_command(Command('aptget install vim', '', ''), None)\
             == 'apt-get install vim'

thefuck/rules/no_command_apt.py

@@ -1,19 +1,23 @@
 from subprocess import Popen, PIPE
 import re
+from thefuck.utils import which
+
+
+def _get_bin(settings):
+    return getattr(settings, 'command_not_found', '/usr/lib/command-not-found')
 
 
 def _get_output(command, settings):
     name = command.script.split(' ')[command.script.startswith('sudo')]
-    check_script = '{} {}'.format(getattr(settings, 'command_not_found',
-                                          '/usr/lib/command-not-found'),
-                                  name)
+    check_script = '{} {}'.format(_get_bin(settings), name)
     result = Popen(check_script, shell=True, stderr=PIPE)
     return result.stderr.read().decode()
 
 
 def match(command, settings):
-    output = _get_output(command, settings)
-    return "No command" in output and "from package" in output
+    if which('apt-get') and which(_get_bin(settings)):
+        output = _get_output(command, settings)
+        return "No command" in output and "from package" in output
 
 
 def get_new_command(command, settings):

thefuck/utils.py

@@ -0,0 +1,19 @@
+import os
+
+
+def which(program):
+    def is_exe(fpath):
+        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+    fpath, fname = os.path.split(program)
+    if fpath:
+        if is_exe(program):
+            return program
+    else:
+        for path in os.environ["PATH"].split(os.pathsep):
+            path = path.strip('"')
+            exe_file = os.path.join(path, program)
+            if is_exe(exe_file):
+                return exe_file
+
+    return None