add missing test

should have been added in 68da04b but the file was not committed

tests/parser/features/test_memory_alloc.py

@@ -0,0 +1,16 @@
+import pytest
+
+from vyper.compiler import compile_code
+from vyper.exceptions import MemoryAllocationException
+
+
+def test_memory_overflow():
+    code = """
+@external
+def zzz(x: DynArray[uint256, 2**59]):  # 2**64 / 32 bytes per word == 2**59
+    y: uint256[7] = [0,0,0,0,0,0,0]
+
+    y[6] = y[5]
+    """
+    with pytest.raises(MemoryAllocationException):
+        compile_code(code)