Fix test failure in LaxBackedNumpyTest.testFrexp4 on Windows.

NumPy is inconsistent between platforms on what it returns for the exponent of an infinite input. On Linux/Mac it returns 0, and on Windows it returns -1. Normalize the test reference result to use 0 in this case.

tests/lax_numpy_test.py

@@ -2311,12 +2311,17 @@ def testFrexp(self, shape, dtype, rng_factory):
         and not config.x64_enabled):
       self.skipTest("Only run float64 testcase when float64 is enabled.")
     rng = rng_factory(self.rng())
-    np_fun = lambda x: np.frexp(x)
-    jnp_fun = lambda x: jnp.frexp(x)
     args_maker = lambda: [rng(shape, dtype)]
-    self._CheckAgainstNumpy(np_fun, jnp_fun, args_maker,
+    def np_frexp(x):
+      mantissa, exponent = np.frexp(x)
+      # NumPy is inconsistent between Windows and Linux/Mac on what the
+      # value of exponent is if the input is infinite. Normalize to the Linux
+      # behavior.
+      exponent = np.where(np.isinf(mantissa), np.zeros_like(exponent), exponent)
+      return mantissa, exponent
+    self._CheckAgainstNumpy(np_frexp, jnp.frexp, args_maker,
                             check_dtypes=np.issubdtype(dtype, np.inexact))
-    self._CompileAndCheck(jnp_fun, args_maker)
+    self._CompileAndCheck(jnp.frexp, args_maker)
 
   @jtu.sample_product(
     [dict(shape=shape, axis1=axis1, axis2=axis2)