A script that takes a valid json file and permute garbage into it to generate test data

permuter.py

#!/usr/bin/env python

import sys, json, copy;
data = json.load(sys.stdin)

def permute(data):
  permutations = [None, "", "wubbalub-gibberish", 1, [], {}]
  if isinstance(data, list):
     if len(data) > 0:
       inner = [[x] for x in permute(data[0])]
       permutations.extend(inner)
  elif isinstance(data, dict):
     for key in data:
         perms = permute(data[key])
         for perm in perms:
             c = copy.deepcopy(data)
             c[key] = perm
             permutations.append(c)
         c = copy.deepcopy(data)
         c.pop(key, None)
         permutations.append(c)
  return permutations

print(len(permute(data)))

for index, permutation in enumerate(permute(data)):
    with open('output-' + str(index) + '.json', 'w') as out:
        json.dump(permutation, out, indent=4, sort_keys=True)