Add command not found handler

tests/rules/test_no_command.py

@@ -0,0 +1,44 @@
+from unittest.mock import patch
+import pytest
+from subprocess import PIPE
+from thefuck.rules.no_command import match, get_new_command
+from thefuck.main import Command
+
+
+@pytest.fixture
+def command_found():
+    return b'''No command 'aptget' found, did you mean:
+ Command 'apt-get' from package 'apt' (main)
+aptget: command not found
+'''
+
+@pytest.fixture
+def command_not_found():
+    return b'''No command 'vom' found, but there are 19 similar ones
+vom: command not found
+'''
+
+
+def test_match(command_found, command_not_found):
+    with patch('thefuck.rules.no_command.Popen') as Popen:
+        Popen.return_value.stderr.read.return_value = command_found
+        assert match(Command('aptget install vim', '', ''))
+        Popen.assert_called_once_with('/usr/lib/command-not-found aptget',
+                                      shell=True, stderr=PIPE)
+        Popen.return_value.stderr.read.return_value = command_not_found
+        assert not match(Command('ls', '', ''))
+
+    with patch('thefuck.rules.no_command.Popen') as Popen:
+        Popen.return_value.stderr.read.return_value = command_found
+        assert match(Command('sudo aptget install vim', '', ''))
+        Popen.assert_called_once_with('/usr/lib/command-not-found aptget',
+                                      shell=True, stderr=PIPE)
+
+
+def test_get_new_command(command_found):
+    with patch('thefuck.rules.no_command._get_output',
+               return_value=command_found.decode()):
+        assert get_new_command(Command('aptget install vim', '', ''))\
+            == 'apt-get install vim'
+        assert get_new_command(Command('sudo aptget install vim', '', '')) \
+            == 'sudo apt-get install vim'