Merge pull request RustPython#2009 from ohgree/test/future

Added CPython 3.8.3's test___future__.py.

Author: youknowone

Lib/test/test___future__.py

@@ -0,0 +1,61 @@
+import unittest
+import __future__
+
+GOOD_SERIALS = ("alpha", "beta", "candidate", "final")
+
+features = __future__.all_feature_names
+
+class FutureTest(unittest.TestCase):
+
+    def test_names(self):
+        # Verify that all_feature_names appears correct.
+        given_feature_names = features[:]
+        for name in dir(__future__):
+            obj = getattr(__future__, name, None)
+            if obj is not None and isinstance(obj, __future__._Feature):
+                self.assertTrue(
+                    name in given_feature_names,
+                    "%r should have been in all_feature_names" % name
+                )
+                given_feature_names.remove(name)
+        self.assertEqual(len(given_feature_names), 0,
+               "all_feature_names has too much: %r" % given_feature_names)
+
+    def test_attributes(self):
+        for feature in features:
+            value = getattr(__future__, feature)
+
+            optional = value.getOptionalRelease()
+            mandatory = value.getMandatoryRelease()
+
+            a = self.assertTrue
+            e = self.assertEqual
+            def check(t, name):
+                a(isinstance(t, tuple), "%s isn't tuple" % name)
+                e(len(t), 5, "%s isn't 5-tuple" % name)
+                (major, minor, micro, level, serial) = t
+                a(isinstance(major, int), "%s major isn't int"  % name)
+                a(isinstance(minor, int), "%s minor isn't int" % name)
+                a(isinstance(micro, int), "%s micro isn't int" % name)
+                a(isinstance(level, str),
+                    "%s level isn't string" % name)
+                a(level in GOOD_SERIALS,
+                       "%s level string has unknown value" % name)
+                a(isinstance(serial, int), "%s serial isn't int" % name)
+
+            check(optional, "optional")
+            if mandatory is not None:
+                check(mandatory, "mandatory")
+                a(optional < mandatory,
+                       "optional not less than mandatory, and mandatory not None")
+
+            a(hasattr(value, "compiler_flag"),
+                   "feature is missing a .compiler_flag attr")
+            # Make sure the compile accepts the flag.
+            compile("", "<test>", "exec", value.compiler_flag)
+            a(isinstance(getattr(value, "compiler_flag"), int),
+                   ".compiler_flag isn't int")
+
+
+if __name__ == "__main__":
+    unittest.main()