Demonstrate leaks in ujson upgrade

test_leaks.py

import ujson
import sys

def test_does_not_leak_dictionary_values():
    import gc
    gc.collect()
    value = ["abc"]
    data = {"1": value}
    ref_count = sys.getrefcount(value)
    ujson.dumps(data)
    assert ref_count == sys.getrefcount(value)

def test_does_not_leak_dictionary_keys():
    import gc
    gc.collect()
    key1 = "1"
    key2 = "1"
    value1 = ["abc"]
    value2 = [1,2,3]
    data = {key1: value1, key2: value2}
    ref_count1 = sys.getrefcount(key1)
    ref_count2 = sys.getrefcount(key2)
    ujson.dumps(data)
    assert ref_count1 == sys.getrefcount(key1)
    assert ref_count2 == sys.getrefcount(key2)

def test_does_not_leak_dictionary_string_key():
    import gc
    gc.collect()
    key1 = "1"
    value1 = 1
    data = {key1: value1}
    ref_count1 = sys.getrefcount(key1)
    ujson.dumps(data)
    assert ref_count1 == sys.getrefcount(key1)

def test_does_not_leak_dictionary_tuple_key():
    import gc
    gc.collect()
    key1 = ("a",)
    value1 = 1
    data = {key1: value1}
    ref_count1 = sys.getrefcount(key1)
    ujson.dumps(data)
    assert ref_count1 == sys.getrefcount(key1)

def test_does_not_leak_dictionary_bytes_key():
    import gc
    gc.collect()
    key1 = b"1"
    value1 = 1
    data = {key1: value1}
    ref_count1 = sys.getrefcount(key1)
    ujson.dumps(data)
    assert ref_count1 == sys.getrefcount(key1)

def test_does_not_leak_dictionary_None_key():
    import gc
    gc.collect()
    key1 = None
    value1 = 1
    data = {key1: value1}
    ref_count1 = sys.getrefcount(key1)
    ujson.dumps(data)
    assert ref_count1 == sys.getrefcount(key1)

tox.ini

# -*- coding: utf-8 -*-

[tox]
skipsdist = true
envlist =
  a
  b
  c

[testenv]
basepython = python2.7
commands =
  pytest -s -vv test_leaks.py

[testenv:a]
deps =
  pytest
  ujson==1.35

[testenv:b]
deps =
  pytest
  ujson==2.0.1

[testenv:c]
deps =
  pytest
  ujson==2.0.2