Pytest changes the behaviour of a generator recursive function - python-3.x

Question

This is my code:
where 'schema' and 'config' are heavily nested dictionaries, this function work as intended when run separately.
def find_config_difference(schema, config, key_name=None):
for k in schema:
try:
if "default" in schema[k] and k in config:
if schema[k]["default"] != config[k]:
out_of_date_default.append(f"key {k} in {key_name} has out of date default value.")
schema[k] = schema[k]["default"]
except TypeError:
pass
finally:
if k in config:
if isinstance((schema[k] and config[k]), dict):
find_config_difference(schema[k], config[k], key_name=k)
else:
yield f"{k} in {key_name} is missing/extra in config"
output = list(find_config_difference(schema, config))
This is my pytest code :
when run through pytest it does not call the function recursively and 'for' loop only goes through the outermost keys of 'schema'.
import unittest
from unittest.mock import patch
from config_compare import *
import ast
config = ast.literal_eval(open('config.json', 'r').read())
schema = ast.literal_eval(open('config_schema.json', 'r').read())
class Test_config_compare(unittest.TestCase):
def test_find_config_difference(self):
missing = list(find_config_difference(schema, config, key_name=None))
length = len(missing)
print(length)
Here is a section of 'schema', which is almost similar to 'config'.
it would only iterate through keys($schema, additionalProperties, definitions, button_content)
schema = {
"$schema": "http://json-schema.org/draft-07/schema#",
"additionalProperties": false,
"definitions": {
"color_hex": {"pattern": "^#([A-Fa-f0-9]{6})$", "type": "string"},
"palette": {
"additionalProperties": false,
"properties": {
"background": {"$ref": "#/definitions/color_hex", "default": "#FFFFFF"},
"primary": {
"rules": {"testTR": 12, "tier": 2},
},
},
},
},
"button_content": {
"additionalProperties": false,
"properties": {
"accessibilityLabel": {"type": "string"},
},
"required": ["accessibilityLabel", "value"],
"type": "object",
},
}
When I removed the yield generator it works fine. But, I also don't want to remove it and store the string in a variable. So is there a way to work around it?

Answer 1

Your recursive function cannot possibly work. It's a generator function, but when you make the recursive call, you're not iterating over the returned generator object. You probably want to yield from the recursive call:
finally:
if k in config:
if isinstance((schema[k] and config[k]), dict):
yield from find_config_difference(schema[k], config[k], key_name=k)
If you want to be selective about which values yielded by the recursion get yielded, you could write your own for loop iterating on the recursive result with whatever logic you want in it, yielding or not as you desire.
All that said, the fact that your function is both a generator that yields values, and it has side effects (such as updating out_of_date_default and some of the schema[k] values) seems like a dubious design. You should probably make your function only do one of those things (either modify things in place, or yield new values, not both).