bpo-37819: Add Fraction.as_integer_ratio() (GH-15212) (GH-15215)

(cherry picked from commit f03b4c8a48f62134799d368b78da35301af466a3)

Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
index 2779162..18ab28c 100644
--- a/Lib/test/test_fractions.py
+++ b/Lib/test/test_fractions.py
@@ -302,6 +302,12 @@
             ValueError, "cannot convert NaN to integer ratio",
             F.from_decimal, Decimal("snan"))
 
+    def test_as_integer_ratio(self):
+        self.assertEqual(F(4, 6).as_integer_ratio(), (2, 3))
+        self.assertEqual(F(-4, 6).as_integer_ratio(), (-2, 3))
+        self.assertEqual(F(4, -6).as_integer_ratio(), (-2, 3))
+        self.assertEqual(F(0, 6).as_integer_ratio(), (0, 1))
+
     def testLimitDenominator(self):
         rpi = F('3.1415926535897932')
         self.assertEqual(rpi.limit_denominator(10000), F(355, 113))