diff -r 939ce500c92a -r 36a940d82f88 tests/hghave.py
--- a/tests/hghave.py	Mon Sep 29 17:23:38 2014 -0500
+++ b/tests/hghave.py	Thu Sep 18 11:43:47 2014 -0700
@@ -281,6 +281,18 @@
 def has_python243():
     return sys.version_info >= (2, 4, 3)
 
+@check("json", "some json module available")
+def has_json():
+    try:
+        if sys.version_info < (2, 7):
+            import simplejson as json
+        else:
+            import json
+        json.dumps
+        return True
+    except ImportError:
+        return False
+
 @check("outer-repo", "outer repo")
 def has_outer_repo():
     # failing for other reasons than 'no repo' imply that there is a repo