Fix test cases that test for equality of NaNs of ml_dtypes floats under NumPy 2.4.3.

NumPy 2.4.3 changed its criterion for when numpy.testing.assert_array_equal will use "equal NaN" semantics. Currently ml_dtypes floats don't appear to be numeric types to NumPy, so NaNs no longer compare as equal. This is actually a helpful change in the future since once ml_dtypes migrates to NumPy 2's user dtype APIs we will be able to declare our types as such.

For now, just cast types to float32 before testing for equality in tests.

PiperOrigin-RevId: 882541951

Author: hawkinsp

ml_dtypes/tests/custom_float_test.py

@@ -900,20 +900,28 @@ def testConformNumpyComplex(self, float_type):
       numpy_assert_allclose(z_np, z_tf, atol=2e-2, float_type=float_type)
 
   def testArange(self, float_type):
+    # TODO(phawkins): remove the casts to float32 once NumPy considers our float
+    # types to be numeric types.
     np.testing.assert_equal(
-        np.arange(1, 100, dtype=np.float32).astype(float_type),
-        np.arange(1, 100, dtype=float_type),
+        np.arange(1, 100, dtype=np.float32)
+        .astype(float_type)
+        .astype(np.float32),
+        np.arange(1, 100, dtype=float_type).astype(np.float32),
     )
     if float_type == float8_e8m0fnu:
       raise self.skipTest("Skip negative ranges for E8M0.")
 
     np.testing.assert_equal(
-        np.arange(-6, 6, 2, dtype=np.float32).astype(float_type),
-        np.arange(-6, 6, 2, dtype=float_type),
+        np.arange(-6, 6, 2, dtype=np.float32)
+        .astype(float_type)
+        .astype(np.float32),
+        np.arange(-6, 6, 2, dtype=float_type).astype(np.float32),
     )
     np.testing.assert_equal(
-        np.arange(-0.0, -2.0, -0.5, dtype=np.float32).astype(float_type),
-        np.arange(-0.0, -2.0, -0.5, dtype=float_type),
+        np.arange(-0.0, -2.0, -0.5, dtype=np.float32)
+        .astype(float_type)
+        .astype(np.float32),
+        np.arange(-0.0, -2.0, -0.5, dtype=float_type).astype(np.float32),
     )
 
   @ignore_warning(category=RuntimeWarning, message="invalid value encountered")