Move all DNS tests into a mock environment

This avoids all of the "flakiness" in the tests and actually tests the
behavior, which is a better test setup.

setup.py

@@ -22,6 +22,19 @@ def get_version():
         return locals['VERSION']
     raise RuntimeError('No version information found.')
 
+
+def tests_require():
+    requirements = [
+        "coverage",
+        "testtools >= 0.9.21",
+        "testscenarios >= 0.3"
+    ]
+
+    if sys.version_info[0] < 3:
+        requirements.append("mock >= 1.0.1")
+
+    return requirements
+
 setup(
     name="pyIsEmail",
     version=get_version(),
@@ -53,11 +66,7 @@ def get_version():
     install_requires=[
         "%s >= 1.10.0" % dnspython,
     ],
-    tests_require=[
-        "coverage",
-        "testtools >= 0.9.21",
-        "testscenarios >= 0.3"
-    ],
+    tests_require=tests_require(),
     test_suite="tests",
     **kwargs
 )

tests/data/tests.xml

@@ -67,7 +67,6 @@ Date       Tests        Version Notes
     <diagnosis>ISEMAIL_VALID</diagnosis>
     <source>Michael Rushton</source>
     <sourcelink>http://squiloople.com/tag/email/</sourcelink>
-    <flaky>True</flaky>
   </test>
   <test id="6">
     <address>@io</address>
@@ -223,11 +222,6 @@ Date       Tests        Version Notes
     <diagnosis>ISEMAIL_VALID</diagnosis>
     <source>Michael Rushton</source>
     <sourcelink>http://squiloople.com/tag/email/</sourcelink>
-    <flaky>True</flaky>
-    <comment>
-      Marked as flaky on 2015-04-15. It seems the DNS record(s) have
-      been removed for this domain, so it is not expected to pass anymore.
-    </comment>
   </test>
   <test id="34">
     <address>test@.iana.org</address>
@@ -686,12 +680,9 @@ Date       Tests        Version Notes
     <address>test@xn--hxajbheg2az3al.xn--jxalpdlp</address>
     <comment>
       A valid IDN from ICANN's <a href="http://idn.icann.org/#The_example.test_names">IDN TLD evaluation gateway</a>.
-      Marked as flaky on 2014-01-27, as the DNS lookup started
-      returning false and the IDN page is down for maintenance.
     </comment>
     <category>ISEMAIL_VALID_CATEGORY</category>
     <diagnosis>ISEMAIL_VALID</diagnosis>
-    <flaky>True</flaky>
     <source>Michael Rushton</source>
     <sourcelink>http://squiloople.com/tag/email/</sourcelink>
   </test>

tests/test_is_email.py

@@ -1,4 +1,3 @@
-from unittest import expectedFailure
 from testscenarios import TestWithScenarios
 from pyisemail import is_email
 from pyisemail.diagnosis import BaseDiagnosis
@@ -7,11 +6,11 @@
 
 class IsEmailTest(TestWithScenarios):
 
-    scenarios = get_scenarios("tests.xml") + get_scenarios("dns-tests.xml")
+    scenarios = get_scenarios("tests.xml")
     threshold = BaseDiagnosis.CATEGORIES['THRESHOLD']
 
     def test_without_diagnosis(self):
-        result = is_email(self.address, check_dns=True)
+        result = is_email(self.address)
         expected = create_diagnosis(self.diagnosis) < self.threshold
 
         self.assertEqual(
@@ -22,58 +21,12 @@ def test_without_diagnosis(self):
         )
 
     def test_with_diagnosis(self):
-        result = is_email(self.address, check_dns=True, diagnose=True)
+        result = is_email(self.address, diagnose=True)
         expected = create_diagnosis(self.diagnosis)
 
-        try:
-            self.assertEqual(
-                result,
-                expected,
-                ("%s (%s): Got %s, but expected %s."
-                 % (self.id, self.address, result, expected))
-            )
-        except AssertionError as err:
-            if self.flaky is True:
-                pass
-            else:
-                raise err
-
-
-class IsEmailFlakyTest(TestWithScenarios):
-
-    """Test suite for flaky is_email tests.
-
-    Due to different DNS servers handling missing domains differently, these
-    tests are marked as flaky. A flaky test might succeed in one environment
-    and fail in another, purely due to DNS issues. An ideal fix for this
-    behavior would be to mock the DNS check to alleviate this problem, but for
-    now this will have to do.
-
-    """
-
-    scenarios = (get_scenarios("tests.xml", flaky=True) +
-                 get_scenarios("dns-tests.xml", flaky=True))
-    threshold = BaseDiagnosis.CATEGORIES['THRESHOLD']
-
-    def test_without_diagnosis(self):
-        result = is_email(self.address, check_dns=True)
-        expected = create_diagnosis(self.diagnosis) < self.threshold
-
         self.assertEqual(
             result,
             expected,
             ("%s (%s): Got %s, but expected %s."
-             % (self.id, self.address, result, expected))
-        )
-
-    @expectedFailure
-    def test_with_diagnosis(self):
-        result = is_email(self.address, check_dns=True, diagnose=True)
-        expected = create_diagnosis(self.diagnosis)
-
-        self.assertEqual(
-            result,
-            expected,
-            ("%s (%s): Got %s, but expected %s."
-             % (self.id, self.address, result, expected))
+                % (self.id, self.address, result, expected))
         )