tests/basics: Add coverage tests for memoryview attributes.

tests/basics/memoryview1.py

@@ -94,3 +94,9 @@ try:
     memoryview(array.array('i'))[0:2] = b'1234'
 except ValueError:
     print('ValueError')
+
+# invalid attribute
+try:
+    memoryview(b'a').noexist
+except AttributeError:
+    print('AttributeError')

tests/basics/memoryview_itemsize.py

@@ -7,3 +7,9 @@ except:
 
 for code in ['b', 'h', 'i', 'l', 'q', 'f', 'd']:
     print(memoryview(array(code)).itemsize)
+
+# shouldn't be able to store to the itemsize attribute
+try:
+    memoryview(b'a').itemsize = 1
+except AttributeError:
+    print('AttributeError')