console

$ py.test test-json-envvar.py
======================================== test session starts ========================================
platform linux2 -- Python 2.7.6, pytest-2.9.2, py-1.4.31, pluggy-0.3.1
rootdir: /home/daniel, inifile:
plugins: hypothesis-3.4.0
collected 1 items

test-json-envvar.py .

===================================== 1 passed in 5.29 seconds ======================================

test-json-envvar.py

# Test environment variable can contain any json encoded value
import sys
import json
from subprocess import check_output
from hypothesis import strategies as st, given

jsonst = st.recursive(
    st.floats(allow_nan=False) | st.booleans() | st.text() | st.none(),
    lambda children: st.lists(children) | st.dictionaries(st.text(), children),
)

CMD = '''
{} -c '
import json, os
value = json.loads(os.getenv("TEST"))
print(json.dumps(value))
'
'''.format(sys.executable)


@given(jsonst)
def test_json_envvar(value):
    enc = json.dumps(value)
    out = check_output(CMD, shell=True, env={'TEST': enc})
    assert json.loads(out) == value