svndiff.py: add ability to compare before-and-after JSON files, not just raw images

gm/gm_json.py

Index: gm/gm_json.py
===================================================================
--- gm/gm_json.py	(revision 10016)
+++ gm/gm_json.py	(working copy)
@@ -49,6 +49,10 @@
 # Allowed hash types for test expectations.
 JSONKEY_HASHTYPE_BITMAP_64BITMD5 = 'bitmap-64bitMD5'
 
+# Pattern used to assemble each image's filename
+IMAGE_FILENAME_PATTERN = '(\S+)_(\S+).png'  # matches (testname, config)

[borenet, 2013/07/16 17:42:13]

Any reason we can't just make this:
IMAGE_FILENAME_RE = re.compile('(\S+)_(\S+).png')
?

[epoger, 2013/07/16 18:22:48]

I think it's better to keep it as a pattern string for the canonical definition,
so that the string can be modified (e.g. assembled into a longer regular
expression) if desired.  Can't go back the other way, from regexp to string...

+
+
 def LoadFromString(file_contents):
   """Loads the JSON summary written out by the GM tool.
      Returns a dictionary keyed by the values listed as JSONKEY_ constants