Add a "test" for divide()

There isn't really anything we can test. We may eventually want to test that
output matches IEEE 754 specifications, but that is harder so we aren't doing
that in general yet.

Author: asmeurer

array_api_tests/test_elementwise_functions.py

@@ -342,7 +342,12 @@ def test_cosh(x):
 def test_divide(args):
     x1, x2 = args
     sanity_check(x1, x2)
-    # a = _array_module.divide(x1, x2)
+    _array_module.divide(x1, x2)
+    # There isn't much we can test here. The spec doesn't require any behavior
+    # beyond the special cases, and indeed, there aren't many mathematical
+    # properties of division that strictly hold for floating-point numbers. We
+    # could test that this does implement IEEE 754 division, but we don't yet
+    # have those sorts in general for this module.
 
 @given(two_any_dtypes.flatmap(lambda i: two_array_scalars(*i)))
 def test_equal(args):