Contract testing basics in Testing Fundamentals - Test Execution Trace

Test Overview

This test checks if a service provider meets the expectations defined by a consumer contract. It verifies that the provider returns the correct response for a given request.

Test Code - unittest

Testing Fundamentals

import unittest

class ProviderService:
    def get_user(self, user_id):
        # Simulate provider response
        if user_id == 1:
            return {"id": 1, "name": "Alice"}
        else:
            return None

class ContractTest(unittest.TestCase):
    def setUp(self):
        self.provider = ProviderService()

    def test_get_user_contract(self):
        # Consumer expects user with id 1 and name Alice
        expected_response = {"id": 1, "name": "Alice"}
        actual_response = self.provider.get_user(1)
        self.assertEqual(actual_response, expected_response)

if __name__ == '__main__':
    unittest.main()

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Test framework initializes and prepares to run tests	-	PASS
2	ProviderService instance is created	ProviderService ready to respond to requests	-	PASS
3	Calls get_user(1) on ProviderService	ProviderService processes request for user id 1	-	PASS
4	Receives response {"id": 1, "name": "Alice"}	Response matches expected contract	Check if actual response equals expected response {"id": 1, "name": "Alice"}	PASS
5	Test completes successfully	All assertions passed, contract is fulfilled	-	PASS

Failure Scenario

Failing Condition: ProviderService returns a different user data or None for user id 1

Execution Trace Quiz - 3 Questions

What does the test verify in contract testing?

A The consumer UI displays the data correctly

B The provider returns the expected response defined by the consumer

C The provider's database connection is active

D The network latency is below threshold

Key Result

Contract testing ensures that the service provider meets the consumer's expectations by verifying the exact response for a given request, preventing integration issues early.