Move setup code to fixtures in decide_user_install unit test

tests/unit/test_decide_user_install.py

@@ -4,7 +4,7 @@
 
 from itertools import product
 
-from pytest import mark, raises
+from pytest import fixture, mark, raises
 
 from pip._internal.commands.install import decide_user_install
 from pip._internal.exceptions import CommandError, InstallationError
@@ -26,6 +26,36 @@ def true(*args, **kwargs):
     return True
 
 
+@fixture
+def user_site_enabled(monkeypatch):
+    """site.ENABLE_USER_SITE mocked to be True."""
+    monkeypatch.setattr(ENABLE_USER_SITE, True)
+
+
+@fixture
+def nonexists(monkeypatch):
+    """os.path.exists mocked to always return False."""
+    monkeypatch.setattr(EXISTS, false)
+
+
+@fixture
+def nonwritable(monkeypatch):
+    """test_writable_dir mocked to always return False."""
+    monkeypatch.setattr(WRITABLE, false)
+
+
+@fixture
+def writable(monkeypatch):
+    """test_writable_dir mocked to always return True."""
+    monkeypatch.setattr(WRITABLE, true)
+
+
+@fixture
+def virtualenv_global(monkeypatch):
+    """virtualenv_no_global mocked to always return False."""
+    monkeypatch.setattr(VIRTUALENV_NO_GLOBAL, false)
+
+
 @mark.parametrize(('use_user_site', 'prefix_path', 'target_dir', 'root_path'),
                   filter(lambda args: sum(map(bool, args)) > 1,
                          product((False, True), (None, 'foo'),
@@ -38,9 +68,8 @@ def test_conflicts(use_user_site, prefix_path, target_dir, root_path):
             target_dir=target_dir, root_path=root_path)
 
 
-def test_target_exists(monkeypatch):
+def test_target_exists(writable, monkeypatch):
     """Test exist target path."""
-    monkeypatch.setattr(WRITABLE, true)
     monkeypatch.setattr(EXISTS, true)
     monkeypatch.setattr(ISDIR, false)
     with raises(InstallationError):
@@ -51,9 +80,8 @@ def test_target_exists(monkeypatch):
         assert decide_user_install(target_dir='bar') is False
 
 
-def test_target_writable(monkeypatch):
+def test_target_writable(nonexists, monkeypatch):
     """Test writable path check with target specified."""
-    monkeypatch.setattr(EXISTS, false)
     monkeypatch.setattr(WRITABLE, false)
     with raises(InstallationError):
         decide_user_install(target_dir='bar')
@@ -70,12 +98,11 @@ def test_prefix_writable(monkeypatch):
     assert decide_user_install(prefix_path='foo') is False
 
 
-def test_global_site_writable(monkeypatch):
+def test_global_site_writable(virtualenv_global, user_site_enabled,
+                              monkeypatch):
     """Test error handling and user site-packages decision
     with writable and non-writable global site-packages.
     """
-    monkeypatch.setattr(VIRTUALENV_NO_GLOBAL, false)
-    monkeypatch.setattr(ENABLE_USER_SITE, True)
     monkeypatch.setattr(WRITABLE, false)
     with raises(InstallationError):
         decide_user_install(use_user_site=False)
@@ -89,11 +116,9 @@ def test_global_site_writable(monkeypatch):
     assert decide_user_install() is False
 
 
-def test_enable_user_site(monkeypatch):
+def test_enable_user_site(virtualenv_global, writable, monkeypatch):
     """Test with different values of site.ENABLE_USER_SITE."""
-    monkeypatch.setattr(VIRTUALENV_NO_GLOBAL, false)
     monkeypatch.setattr(ENABLE_USER_SITE, None)
-    monkeypatch.setattr(WRITABLE, true)
     assert decide_user_install() is False
     assert decide_user_install(use_user_site=False) is False
     with raises(InstallationError):
@@ -107,18 +132,14 @@ def test_enable_user_site(monkeypatch):
     monkeypatch.setattr(ENABLE_USER_SITE, True)
     assert decide_user_install(use_user_site=False) is False
     assert decide_user_install(use_user_site=True) is True
-    monkeypatch.setattr(WRITABLE, false)
-    assert decide_user_install() is True
 
 
-def test_virtualenv_no_global(monkeypatch):
+def test_virtualenv_no_global(user_site_enabled, nonwritable, monkeypatch):
     """Test for final assertion of virtualenv_no_global
     when user site-packages is decided to be used.
     """
     monkeypatch.setattr(VIRTUALENV_NO_GLOBAL, true)
     with raises(InstallationError):
         decide_user_install(use_user_site=True)
-    monkeypatch.setattr(ENABLE_USER_SITE, True)
-    monkeypatch.setattr(WRITABLE, false)
     with raises(InstallationError):
         decide_user_install()