[3.13] Use subTest() in math.fma() tests (GH-131125) (#131132)

Use subTest() in math.fma() tests (GH-131125)
(cherry picked from commit 52756c3)

Co-authored-by: Sergey B Kirpichev <[email protected]>

Author: miss-islington

Lib/test/test_math.py

@@ -2637,9 +2637,10 @@ def test_fma_nan_results(self):
 
         # If any input is a NaN, the result should be a NaN, too.
         for a, b in itertools.product(values, repeat=2):
-            self.assertIsNaN(math.fma(math.nan, a, b))
-            self.assertIsNaN(math.fma(a, math.nan, b))
-            self.assertIsNaN(math.fma(a, b, math.nan))
+            with self.subTest(a=a, b=b):
+                self.assertIsNaN(math.fma(math.nan, a, b))
+                self.assertIsNaN(math.fma(a, math.nan, b))
+                self.assertIsNaN(math.fma(a, b, math.nan))
 
     def test_fma_infinities(self):
         # Cases involving infinite inputs or results.
@@ -2651,57 +2652,62 @@ def test_fma_infinities(self):
         for c in non_nans:
             for infinity in [math.inf, -math.inf]:
                 for zero in [0.0, -0.0]:
-                    with self.assertRaises(ValueError):
-                        math.fma(infinity, zero, c)
-                    with self.assertRaises(ValueError):
-                        math.fma(zero, infinity, c)
+                    with self.subTest(c=c, infinity=infinity, zero=zero):
+                        with self.assertRaises(ValueError):
+                            math.fma(infinity, zero, c)
+                        with self.assertRaises(ValueError):
+                            math.fma(zero, infinity, c)
 
         # ValueError when a*b and c both infinite of opposite signs.
         for b in positives:
-            with self.assertRaises(ValueError):
-                math.fma(math.inf, b, -math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(math.inf, -b, math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(-math.inf, -b, -math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(-math.inf, b, math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(b, math.inf, -math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(-b, math.inf, math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(-b, -math.inf, -math.inf)
-            with self.assertRaises(ValueError):
-                math.fma(b, -math.inf, math.inf)
+            with self.subTest(b=b):
+                with self.assertRaises(ValueError):
+                    math.fma(math.inf, b, -math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(math.inf, -b, math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(-math.inf, -b, -math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(-math.inf, b, math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(b, math.inf, -math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(-b, math.inf, math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(-b, -math.inf, -math.inf)
+                with self.assertRaises(ValueError):
+                    math.fma(b, -math.inf, math.inf)
 
         # Infinite result when a*b and c both infinite of the same sign.
         for b in positives:
-            self.assertEqual(math.fma(math.inf, b, math.inf), math.inf)
-            self.assertEqual(math.fma(math.inf, -b, -math.inf), -math.inf)
-            self.assertEqual(math.fma(-math.inf, -b, math.inf), math.inf)
-            self.assertEqual(math.fma(-math.inf, b, -math.inf), -math.inf)
-            self.assertEqual(math.fma(b, math.inf, math.inf), math.inf)
-            self.assertEqual(math.fma(-b, math.inf, -math.inf), -math.inf)
-            self.assertEqual(math.fma(-b, -math.inf, math.inf), math.inf)
-            self.assertEqual(math.fma(b, -math.inf, -math.inf), -math.inf)
+            with self.subTest(b=b):
+                self.assertEqual(math.fma(math.inf, b, math.inf), math.inf)
+                self.assertEqual(math.fma(math.inf, -b, -math.inf), -math.inf)
+                self.assertEqual(math.fma(-math.inf, -b, math.inf), math.inf)
+                self.assertEqual(math.fma(-math.inf, b, -math.inf), -math.inf)
+                self.assertEqual(math.fma(b, math.inf, math.inf), math.inf)
+                self.assertEqual(math.fma(-b, math.inf, -math.inf), -math.inf)
+                self.assertEqual(math.fma(-b, -math.inf, math.inf), math.inf)
+                self.assertEqual(math.fma(b, -math.inf, -math.inf), -math.inf)
 
         # Infinite result when a*b finite, c infinite.
         for a, b in itertools.product(finites, finites):
-            self.assertEqual(math.fma(a, b, math.inf), math.inf)
-            self.assertEqual(math.fma(a, b, -math.inf), -math.inf)
+            with self.subTest(b=b):
+                self.assertEqual(math.fma(a, b, math.inf), math.inf)
+                self.assertEqual(math.fma(a, b, -math.inf), -math.inf)
 
         # Infinite result when a*b infinite, c finite.
         for b, c in itertools.product(positives, finites):
-            self.assertEqual(math.fma(math.inf, b, c), math.inf)
-            self.assertEqual(math.fma(-math.inf, b, c), -math.inf)
-            self.assertEqual(math.fma(-math.inf, -b, c), math.inf)
-            self.assertEqual(math.fma(math.inf, -b, c), -math.inf)
+            with self.subTest(b=b, c=c):
+                self.assertEqual(math.fma(math.inf, b, c), math.inf)
+                self.assertEqual(math.fma(-math.inf, b, c), -math.inf)
+                self.assertEqual(math.fma(-math.inf, -b, c), math.inf)
+                self.assertEqual(math.fma(math.inf, -b, c), -math.inf)
 
-            self.assertEqual(math.fma(b, math.inf, c), math.inf)
-            self.assertEqual(math.fma(b, -math.inf, c), -math.inf)
-            self.assertEqual(math.fma(-b, -math.inf, c), math.inf)
-            self.assertEqual(math.fma(-b, math.inf, c), -math.inf)
+                self.assertEqual(math.fma(b, math.inf, c), math.inf)
+                self.assertEqual(math.fma(b, -math.inf, c), -math.inf)
+                self.assertEqual(math.fma(-b, -math.inf, c), math.inf)
+                self.assertEqual(math.fma(-b, math.inf, c), -math.inf)
 
     # gh-73468: On some platforms, libc fma() doesn't implement IEE 754-2008
     # properly: it doesn't use the right sign when the result is zero.
@@ -2714,23 +2720,24 @@ def test_fma_zero_result(self):
 
         # Zero results from exact zero inputs.
         for b in nonnegative_finites:
-            self.assertIsPositiveZero(math.fma(0.0, b, 0.0))
-            self.assertIsPositiveZero(math.fma(0.0, b, -0.0))
-            self.assertIsNegativeZero(math.fma(0.0, -b, -0.0))
-            self.assertIsPositiveZero(math.fma(0.0, -b, 0.0))
-            self.assertIsPositiveZero(math.fma(-0.0, -b, 0.0))
-            self.assertIsPositiveZero(math.fma(-0.0, -b, -0.0))
-            self.assertIsNegativeZero(math.fma(-0.0, b, -0.0))
-            self.assertIsPositiveZero(math.fma(-0.0, b, 0.0))
-
-            self.assertIsPositiveZero(math.fma(b, 0.0, 0.0))
-            self.assertIsPositiveZero(math.fma(b, 0.0, -0.0))
-            self.assertIsNegativeZero(math.fma(-b, 0.0, -0.0))
-            self.assertIsPositiveZero(math.fma(-b, 0.0, 0.0))
-            self.assertIsPositiveZero(math.fma(-b, -0.0, 0.0))
-            self.assertIsPositiveZero(math.fma(-b, -0.0, -0.0))
-            self.assertIsNegativeZero(math.fma(b, -0.0, -0.0))
-            self.assertIsPositiveZero(math.fma(b, -0.0, 0.0))
+            with self.subTest(b=b):
+                self.assertIsPositiveZero(math.fma(0.0, b, 0.0))
+                self.assertIsPositiveZero(math.fma(0.0, b, -0.0))
+                self.assertIsNegativeZero(math.fma(0.0, -b, -0.0))
+                self.assertIsPositiveZero(math.fma(0.0, -b, 0.0))
+                self.assertIsPositiveZero(math.fma(-0.0, -b, 0.0))
+                self.assertIsPositiveZero(math.fma(-0.0, -b, -0.0))
+                self.assertIsNegativeZero(math.fma(-0.0, b, -0.0))
+                self.assertIsPositiveZero(math.fma(-0.0, b, 0.0))
+
+                self.assertIsPositiveZero(math.fma(b, 0.0, 0.0))
+                self.assertIsPositiveZero(math.fma(b, 0.0, -0.0))
+                self.assertIsNegativeZero(math.fma(-b, 0.0, -0.0))
+                self.assertIsPositiveZero(math.fma(-b, 0.0, 0.0))
+                self.assertIsPositiveZero(math.fma(-b, -0.0, 0.0))
+                self.assertIsPositiveZero(math.fma(-b, -0.0, -0.0))
+                self.assertIsNegativeZero(math.fma(b, -0.0, -0.0))
+                self.assertIsPositiveZero(math.fma(b, -0.0, 0.0))
 
         # Exact zero result from nonzero inputs.
         self.assertIsPositiveZero(math.fma(2.0, 2.0, -4.0))
@@ -2836,12 +2843,14 @@ def test_random(self):
              '0x1.f5467b1911fd6p-2', '0x1.b5cee3225caa5p-1'),
         ]
         for a_hex, b_hex, c_hex, expected_hex in test_values:
-            a = float.fromhex(a_hex)
-            b = float.fromhex(b_hex)
-            c = float.fromhex(c_hex)
-            expected = float.fromhex(expected_hex)
-            self.assertEqual(math.fma(a, b, c), expected)
-            self.assertEqual(math.fma(b, a, c), expected)
+            with self.subTest(a_hex=a_hex, b_hex=b_hex, c_hex=c_hex,
+                              expected_hex=expected_hex):
+                a = float.fromhex(a_hex)
+                b = float.fromhex(b_hex)
+                c = float.fromhex(c_hex)
+                expected = float.fromhex(expected_hex)
+                self.assertEqual(math.fma(a, b, c), expected)
+                self.assertEqual(math.fma(b, a, c), expected)
 
     # Custom assertions.
     def assertIsNaN(self, value):