[python] Add negative MemoryBuffer testcase

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153248 91177308-0d34-0410-b5e6-96231b3b80d8

bindings/python/llvm/tests/test_core.py

@@ -16,3 +16,8 @@ class TestCore(TestBase):
         source = self.get_test_binary()
 
         MemoryBuffer(filename=source)
+
+    def test_memory_buffer_failing(self):
+        with self.assertRaises(Exception):
+            MemoryBuffer(filename="/hopefully/this/path/doesnt/exist")
+