Show user's $EDITOR in output

It looks nicer with confirmation and also checks the user actually has an
$EDITOR.

tests/rules/test_fix_file.py

@@ -1,4 +1,5 @@
 import pytest
+import os
 from thefuck.rules.fix_file import match, get_new_command
 from tests.utils import Command
 
@@ -157,11 +158,21 @@ ReferenceError: conole is not defined
 
 
 @pytest.mark.parametrize('test', tests)
-def test_match(test):
+def test_match(monkeypatch, test):
+    monkeypatch.setenv('EDITOR', 'dummy_editor')
     assert match(Command(stderr=test[4]), None)
 
 
+@pytest.mark.parametrize('test', tests)
+def test_not_match(monkeypatch, test):
+    if 'EDITOR' in os.environ:
+        monkeypatch.delenv('EDITOR')
+
+    assert not match(Command(stderr=test[4]), None)
+
+
 @pytest.mark.parametrize('test', tests)
 def test_get_new_command(monkeypatch, test):
+    monkeypatch.setenv('EDITOR', 'dummy_editor')
     assert (get_new_command(Command(script=test[0], stderr=test[4]), None) ==
-        '$EDITOR {} +{} && {}'.format(test[1], test[2], test[0]))
+        'dummy_editor {} +{} && {}'.format(test[1], test[2], test[0]))

thefuck/rules/fix_file.py

@@ -1,4 +1,5 @@
 import re
+import os
 from thefuck.utils import memoize
 from thefuck import shells
 
@@ -49,7 +50,7 @@ def _search(stderr):
 
 
 def match(command, settings):
-    return _search(command.stderr)
+    return 'EDITOR' in os.environ and _search(command.stderr)
 
 
 def get_new_command(command, settings):
@@ -57,5 +58,5 @@ def get_new_command(command, settings):
 
     # Note: there does not seem to be a standard for columns, so they are just
     # ignored for now
-    return shells.and_('$EDITOR {} +{}'.format(m.group('file'), m.group('line')),
+    return shells.and_('{} {} +{}'.format(os.environ['EDITOR'], m.group('file'), m.group('line')),
                        command.script)