Add test for binary operation in enum definition

testing/cffi0/test_parsing.py

@@ -386,10 +386,10 @@
 def test_enum():
     ffi = FFI()
     ffi.cdef("""
-        enum Enum { POS = +1, TWO = 2, NIL = 0, NEG = -1};
+        enum Enum { POS = +1, TWO = 2, NIL = 0, NEG = -1, OP = (POS+TWO)-1};
         """)
     C = ffi.dlopen(None)
     assert C.POS == 1
     assert C.TWO == 2
     assert C.NIL == 0
     assert C.NEG == -1
@@ -390,9 +390,10 @@
         """)
     C = ffi.dlopen(None)
     assert C.POS == 1
     assert C.TWO == 2
     assert C.NIL == 0
     assert C.NEG == -1
+    assert C.OP == 2
 
 def test_stdcall():
     ffi = FFI()