TST: Add some tests around (c)math.nan and nan parsing signs

python · May 7, 2023 · fd39437 · fd39437
1 parent 230882c
commit fd39437
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Showing 4 changed files with 15 additions and 6 deletions.
diff --git a/Lib/test/test_cmath.py b/Lib/test/test_cmath.py
@@ -166,6 +166,11 @@ def test_infinity_and_nan_constants(self):
         self.assertEqual(cmath.nan.imag, 0.0)
         self.assertEqual(cmath.nanj.real, 0.0)
         self.assertTrue(math.isnan(cmath.nanj.imag))
+        # Also check that the sign of all of these is positive:
+        self.assertEqual(math.copysign(1., cmath.nan.real), 1.)
+        self.assertEqual(math.copysign(1., cmath.nan.imag), 1.)
+        self.assertEqual(math.copysign(1., cmath.nanj.real), 1.)
+        self.assertEqual(math.copysign(1., cmath.nanj.imag), 1.)
 
         # Check consistency with reprs.
         self.assertEqual(repr(cmath.inf), "inf")

diff --git a/Lib/test/test_complex.py b/Lib/test/test_complex.py
@@ -529,6 +529,12 @@ class complex2(complex):
                     self.assertFloatsAreIdentical(z.real, x)
                     self.assertFloatsAreIdentical(z.imag, y)
 
+    def test_constructor_negative_nans_from_string(self):
+        self.assertEqual(copysign(1., complex("-nan").real), -1.)
+        self.assertEqual(copysign(1., complex("-nanj").imag), -1.)
+        self.assertEqual(copysign(1., complex("-nan-nanj").real), -1.)
+        self.assertEqual(copysign(1., complex("-nan-nanj").imag), -1.)
+
     def test_underscores(self):
         # check underscores
         for lit in VALID_UNDERSCORE_LITERALS:
@@ -569,6 +575,7 @@ def test(v, expected, test_fn=self.assertEqual):
         test(complex(NAN, 1), "(nan+1j)")
         test(complex(1, NAN), "(1+nanj)")
         test(complex(NAN, NAN), "(nan+nanj)")
+        test(complex(-NAN, -NAN), "(nan+nanj)")
 
         test(complex(0, INF), "infj")
         test(complex(0, -INF), "-infj")

diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py
@@ -1040,11 +1040,8 @@ def test_inf_signs(self):
         self.assertEqual(copysign(1.0, float('inf')), 1.0)
         self.assertEqual(copysign(1.0, float('-inf')), -1.0)
 
-    @unittest.skipUnless(getattr(sys, 'float_repr_style', '') == 'short',
-                         "applies only when using short float repr style")
     def test_nan_signs(self):
-        # When using the dtoa.c code, the sign of float('nan') should
-        # be predictable.
+        # The sign of float('nan') should be predictable.
         self.assertEqual(copysign(1.0, float('nan')), 1.0)
         self.assertEqual(copysign(1.0, float('-nan')), -1.0)
 

diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
@@ -1881,11 +1881,11 @@ def testIsinf(self):
         self.assertFalse(math.isinf(0.))
         self.assertFalse(math.isinf(1.))
 
-    @requires_IEEE_754
     def test_nan_constant(self):
+        # `math.nan` must be a quiet NaN with positive sign bit
         self.assertTrue(math.isnan(math.nan))
+        self.assertEqual(math.copysign(1., math.nan), 1.)
 
-    @requires_IEEE_754
     def test_inf_constant(self):
         self.assertTrue(math.isinf(math.inf))
         self.assertGreater(math.inf, 0.0)