Reset CollectorRegistry of Prometheus lib after each unit test

Question

I have a class A that initializes a Counter in its init

from prometheus_client import Counter
class A:
    def __init__(self):
        self.my_counter = Counter('an_awesome_counter')
    def method_1(self):
        return 1
    def method_2(self):
        return 2

Then I write test class :

import unittest
import A

class ATests(unittest.TestCase):
    def setUp(self):
        self.a = A()
    def tearDown(self):
        self.a = None
    def method_1_test(self):
        ....
    def method_2_test(self):
        ....

Thing is, if I run the test separately, they are fine. Yet when I run them together (Run the whole ATests class), I have the error as:

ValueError: Duplicated timeseries in CollectorRegistry: {'an_awesome_counter'}

So it seems that the python environment isn't reset after each test run. I check the CollectorRegistry and there is a method to unregister collector, but it seems a bit ugly to do that.

I wonder if there is another way to solve this problem? Like forcing the test to run with new environment every time for example..

Thank you.

Answer 1

For the moment, I moved a = A() out of setup(self) and turned it into a class variable as a workaround solution