adding dummy history backend

xonsh/history/__init__.py

@@ -3,11 +3,13 @@
 import builtins
 import time
 
+from xonsh.history.dummy import History as DummyHistory
 from xonsh.history.json import History as JsonHistory
 from xonsh.history.json import history_main
 from xonsh.history.sqlite import History as SqliteHistory
 
 _BACKENDS = {
+    'dummy': DummyHistory,
     'json': JsonHistory,
     'sqlite': SqliteHistory,
 }
@@ -15,8 +17,7 @@ _BACKENDS = {
 
 def get_history_backend(env, ts, locked, gc=True, filename=None):
     env = builtins.__xonsh_env__
-    backend = env.get('XONSH_HISTORY_BACKEND', 'sqlite')
-    print('backend str: {}'.format(backend))
+    backend = env.get('XONSH_HISTORY_BACKEND', 'json')
     try:
         kls_history = _BACKENDS[backend]
     except KeyError:

xonsh/history/dummy.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+"""Implements the xonsh history backend."""
+import threading
+
+
+class HistoryGC(threading.Thread):
+    pass
+
+
+class History:
+    def __init__(self, gc=True, **kwargs):
+        self.gc = HistoryGC() if gc else None
+        self.rtns = None
+        self.last_cmd_rtn = None
+        self.last_cmd_out = None
+
+    def __iter__(self):
+        for cmd, ts, index in []:
+            yield (cmd, ts, index)
+
+    def append(self, cmd):
+        print('DummyHistory append cmd: {}'.format(cmd))
+
+    def flush(self, at_exit=False):
+        print('DummyHistory flush() called')
+
+    def get_history_items(self):
+        return [{'inp': 'dummy in action\n'}]