tests: temporarily modify global configuration

test/_common.py

@@ -17,6 +17,8 @@ import time
 import sys
 import os
 import logging
+import contextlib
+import copy
 
 # Use unittest2 on Python < 2.7.
 try:
@@ -28,6 +30,7 @@ except ImportError:
 sys.path.insert(0, '..')
 import beets.library
 from beets import importer
+import beets
 
 # Suppress logging output.
 log = logging.getLogger('beets')
@@ -75,6 +78,19 @@ def item():
 def import_session(lib, logfile=None, paths=[], query=[]):
     return importer.ImportSession(lib, logfile, paths, query)
 
+# Temporary config modifications.
+@contextlib.contextmanager
+def temp_config():
+    """A context manager that saves and restores beets' global
+    configuration. This allows tests to make temporary modifications
+    that will then be automatically removed when the context exits.
+    """
+    old_sources = copy.deepcopy(beets.config.sources)
+    old_overlay = copy.deepcopy(beets.config.overlay)
+    yield
+    beets.config.sources = old_sources
+    beets.config.overlay = old_overlay
+
 
 # Mock timing.
 

test/test_art.py

@@ -265,13 +265,15 @@ class ArtImporterTest(unittest.TestCase, _common.ExtraAsserts):
         self.assertExists(self.art_file)
 
     def test_delete_original_file(self):
-        config['import']['delete'] = True
-        self._fetch_art(True)
+        with _common.temp_config():
+            config['import']['delete'] = True
+            self._fetch_art(True)
         self.assertNotExists(self.art_file)
 
     def test_move_original_file(self):
-        config['import']['move'] = True
-        self._fetch_art(True)
+        with _common.temp_config():
+            config['import']['move'] = True
+            self._fetch_art(True)
         self.assertNotExists(self.art_file)
 
     def test_do_not_delete_original_if_already_in_place(self):

test/test_ui.py

@@ -589,8 +589,9 @@ class ShowdiffTest(unittest.TestCase):
         self.assertTrue('field' in out)
 
     def test_showdiff_ints_no_color(self):
-        config['color'] = False
-        commands._showdiff('field', 2, 3)
+        with _common.temp_config():
+            config['color'] = False
+            commands._showdiff('field', 2, 3)
         out = self.io.getoutput()
         self.assertTrue('field' in out)