added regression test write_before_map.py

tests/regress/write_before_map.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+from unicorn import *
+from unicorn.x86_const import *
+
+import regress
+
+X86_CODE64 = "\x90" # NOP
+
+
+class WriteBeforeMap(regress.RegressTest):
+    def runTest(self):
+        # Initialize emulator in X86-32bit mode
+        mu = Uc(UC_ARCH_X86, UC_MODE_64)
+
+        # memory address where emulation starts
+        ADDRESS = 0x1000000
+
+        # write machine code to be emulated to memory
+        mu.mem_write(ADDRESS, X86_CODE64)
+
+
+if __name__ == '__main__':
+    regress.main()