Use assertEqual(). (#13886)

diff --git a/Lib/ctypes/test/test_arrays.py b/Lib/ctypes/test/test_arrays.py
index 9e41f45..63a00b9 100644
--- a/Lib/ctypes/test/test_arrays.py
+++ b/Lib/ctypes/test/test_arrays.py
@@ -199,7 +199,7 @@
             _fields_ = []
 
         obj = (EmptyStruct * 2)()  # bpo37188: Floating point exception
-        assert sizeof(obj) == 0
+        self.assertEqual(sizeof(obj), 0)
 
     def test_empty_element_array(self):
         class EmptyArray(Array):
@@ -207,7 +207,7 @@
             _length_ = 0
 
         obj = (EmptyArray * 2)()  # bpo37188: Floating point exception
-        assert sizeof(obj) == 0
+        self.assertEqual(sizeof(obj), 0)
 
     def test_bpo36504_signed_int_overflow(self):
         # The overflow check in PyCArrayType_new() could cause signed integer