improve code in tests

- use 'assertRaises' as context manager
- remove calls to .keys()

test/test_cookies.py

@@ -86,14 +86,14 @@ class TestCookiedict(unittest.TestCase):
     def test_dict(self):
         cookies = extractor.find("test:").session.cookies
         self.assertEqual(len(cookies), len(self.cdict))
-        self.assertEqual(sorted(cookies.keys()), sorted(self.cdict.keys()))
+        self.assertEqual(sorted(cookies), sorted(self.cdict))
         self.assertEqual(sorted(cookies.values()), sorted(self.cdict.values()))
 
     def test_domain(self):
         for category in ["exhentai", "nijie", "sankaku", "seiga"]:
             extr = _get_extractor(category)
             cookies = extr.session.cookies
-            for key in self.cdict.keys():
+            for key in self.cdict:
                 self.assertTrue(key in cookies)
             for c in cookies:
                 self.assertEqual(c.domain, extr.cookiedomain)

test/test_results.py

@@ -55,7 +55,8 @@ class TestExtractorResults(unittest.TestCase):
         if not result:
             return
         if "exception" in result:
-            self.assertRaises(result["exception"], tjob.run)
+            with self.assertRaises(result["exception"]):
+                tjob.run()
             return
         try:
             tjob.run()

test/test_util.py

@@ -304,12 +304,17 @@ class TestOther(unittest.TestCase):
             util.advance(util.advance(items, 1), 2), range(3, 5))
 
     def test_raises(self):
-        self.assertRaises(Exception, util.raises(Exception()))
+        func = util.raises(Exception())
+        with self.assertRaises(Exception):
+            func()
 
         func = util.raises(ValueError(1))
-        self.assertRaises(Exception, func)
-        self.assertRaises(Exception, func)
-        self.assertRaises(Exception, func)
+        with self.assertRaises(ValueError):
+            func()
+        with self.assertRaises(ValueError):
+            func()
+        with self.assertRaises(ValueError):
+            func()
 
     def test_combine_dict(self):
         self.assertEqual(