bpo-26680: Adds tests for Fraction.is_integer called as an instance method.

The tests for the Rational abstract base class use an unbound
method to sidestep the inability to directly instantiate Rational.
These tests check that everything works correct as an instance method.

Author: rob-smallshire

Lib/test/test_fractions.py

@@ -724,6 +724,17 @@ def denominator(self):
         self.assertEqual(type(f.numerator), myint)
         self.assertEqual(type(f.denominator), myint)
 
+    def test_is_integer(self):
+        # Issue #26680: Incorporating number.is_integer into Fraction
+        self.assertTrue(F(-1, 1).is_integer())
+        self.assertTrue(F(0, 1).is_integer())
+        self.assertTrue(F(1, 1).is_integer())
+        self.assertTrue(F(42, 1).is_integer())
+        self.assertTrue(F(2, 2).is_integer())
+        self.assertTrue(F(8, 4).is_integer())
+        self.assertFalse(F(1, 2).is_integer())
+        self.assertFalse(F(1, 3).is_integer())
+        self.assertFalse(F(2, 3).is_integer())
 
 if __name__ == '__main__':
     unittest.main()