simplify

tests/rules/test_nix_shell.py

@@ -1,6 +1,5 @@
 import pytest
 from thefuck.rules.nix_shell import get_nixpkgs_name, get_new_command
-from thefuck.rules import nix_shell
 from thefuck.types import Command
 from unittest.mock import patch
 
@@ -15,9 +14,8 @@ mocked_nixpkgs = {
     "command, output", [("lsof", "lsof"), ("xev", "xorg.xev"), ("foo", "")]
 )
 def test_get_nixpkgs_name(command, output):
-    """ Check that `get_nixpkgs_name` returns the correct name """
+    """Check that `get_nixpkgs_name` returns the correct name"""
 
-    nix_shell.nixpkgs_name = ""
     with patch("subprocess.run") as mocked_run:
         instance = mocked_run.return_value
         instance.stderr = mocked_nixpkgs[command]
@@ -25,15 +23,18 @@ def test_get_nixpkgs_name(command, output):
 
 
 # check that flags and params are preserved for the new command
-@pytest.mark.parametrize('command_script, new_command', [
-    ('lsof -i :3000', 'nix-shell -p lsof --run "lsof -i :3000"'),
-    ('xev', 'nix-shell -p xorg.xev --run "xev"')])
+@pytest.mark.parametrize(
+    "command_script, new_command",
+    [
+        ("lsof -i :3000", 'nix-shell -p lsof --run "lsof -i :3000"'),
+        ("xev", 'nix-shell -p xorg.xev --run "xev"'),
+    ],
+)
 def test_get_new_command(command_script, new_command):
-    """ Check that flags and params are preserved in the new command """
+    """Check that flags and params are preserved in the new command"""
 
-    nix_shell.nixpkgs_name = ""
-    command = Command(command_script, '')
-    with patch('subprocess.run') as mocked_run:
+    command = Command(command_script, "")
+    with patch("subprocess.run") as mocked_run:
         instance = mocked_run.return_value
         instance.stderr = mocked_nixpkgs[command.script_parts[0]]
         assert get_new_command(command) == new_command

thefuck/rules/nix_shell.py

@@ -8,20 +8,12 @@ enabled_by_default = nix_available
 priority = 999
 
 
-nixpkgs_name = ""
-
-
 def get_nixpkgs_name(bin):
     """
     Returns the name of the Nix package that provides the given binary. It uses the
     `command-not-found` binary to do so, which is how nix-shell generates it's own suggestions.
     """
 
-    # Avoid getting the nixpkgs_name twice
-    global nixpkgs_name
-    if nixpkgs_name:
-        return nixpkgs_name
-
     result = subprocess.run(
         ["command-not-found", bin], stderr=subprocess.PIPE, universal_newlines=True
     )