Update the unit test to cover the list of running processes

Author: xusheng6

test/debugger_test.py

@@ -343,6 +343,8 @@ def test_attach(self):
         self.assertIsNotNone(pid)
         bv = load(fpath)
         dbg = DebuggerController(bv)
+        processes = dbg.processes
+        self.assertGreater(len(processes), 0)
         dbg.pid_attach = pid
         self.assertTrue(dbg.attach_and_wait())
         self.assertGreater(len(dbg.regs), 0)