Fix tests in scripts/ for Python 3.12 by correcting mock assertion usage

[avirajsingh7]

Summary

This PR fixes a compatibility issue with Python 3.12 that caused all tests in the scripts/ directory to fail due to incorrect usage of called_once_with on a mock object.

Target issue is #228

In Python 3.11 and earlier, using called_once_with as an attribute on a mock did not raise an error. However, Python 3.12 enforces stricter checks, and using called_once_with directly now results in:

• Replaced incorrect called_once_with usage with the correct assert_called_once_with(...) assertion.
• Properly mocked the Session context manager and select call inside the init() function.
• Ensured the test simulates a successful DB connection scenario.

Checklist

Before submitting a pull request, please ensure that you mark these task.

• Ran fastapi run --reload app/main.py or docker compose up in the repository root and test.
• If you've fixed a bug or added code that is tested and has test cases.

Summary by CodeRabbit

• Tests
  • Simplified and consolidated tests for backend and test initialization processes, replacing previous tests with streamlined versions that focus on successful connection scenarios.

[coderabbitai]

Walkthrough

The test files for backend and test pre-start initialization were refactored to consolidate their logic. Each now contains a single, simplified test that mocks session and select behavior, removes logger patching, and focuses on verifying successful execution of the init function by checking that the session's exec method is called as expected.

Changes

File(s)	Change Summary
backend/app/tests/scripts/test_backend_pre_start.py, backend/app/tests/scripts/test_test_pre_start.py	Refactored tests: removed test_init_successful_connection, added test_init_success, simplified mocks, removed logger patching, and streamlined test logic to focus on session execution and success verification.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

In the warren where tests reside,
Refactoring swept the old aside.
With mocks and patches, clean and neat,
The rabbit ensures connections complete.
Fewer lines, a lighter load—
Hippity-hop down the testing road! 🐇

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📥 Commits

Reviewing files that changed from the base of the PR and between f1d651b and 0b086a8.

📒 Files selected for processing (2)

• backend/app/tests/scripts/test_backend_pre_start.py (1 hunks)
• backend/app/tests/scripts/test_test_pre_start.py (1 hunks)

🧰 Additional context used

🧬 Code Graph Analysis (1)

backend/app/tests/scripts/test_test_pre_start.py (1)

backend/app/tests_pre_start.py (1)

• init (22-29)

🔇 Additional comments (10)

backend/app/tests/scripts/test_test_pre_start.py (5)

2-2: LGTM: Import statement is correct.

The import correctly references the init function from app.tests_pre_start module.

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5-8: LGTM: Proper mock setup for Session context manager.

The mock session setup correctly implements the context manager protocol by setting __enter__ to return the mock session itself, and configures the exec method to return None. This accurately simulates the behavior expected by the init function.

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10-13: LGTM: Appropriate patching strategy.

The patching approach correctly mocks both the Session constructor and the select function within the app.tests_pre_start module scope, ensuring the test has full control over the dependencies.

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15-15: LGTM: Correct function invocation.

Calling init with a MagicMock() engine is appropriate since the actual engine parameter isn't used when the Session constructor is mocked.

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23-23: LGTM: Correct assertion method for Python 3.12 compatibility.

Using assert_called_once_with(fake_select) is the correct approach for Python 3.12. This fixes the compatibility issue mentioned in the PR objectives where called_once_with was incorrectly used as an attribute instead of a proper assertion method.

backend/app/tests/scripts/test_backend_pre_start.py (5)

2-2: LGTM: Import statement is correct.

The import correctly references the init function from app.backend_pre_start module.

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5-8: LGTM: Consistent mock setup for Session context manager.

The mock session setup is identical to the other test file and correctly implements the context manager protocol, ensuring consistency across the test suite.

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11-13: LGTM: Correct module-specific patching.

The patching correctly targets app.backend_pre_start.Session and app.backend_pre_start.select, ensuring the mocks are applied to the correct module scope for this test.

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15-15: LGTM: Appropriate function call.

Calling init with a MagicMock() engine is consistent with the other test and appropriate for this mocked scenario.

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23-23: LGTM: Python 3.12 compatible assertion.

The use of assert_called_once_with(fake_select) correctly addresses the Python 3.12 compatibility issue by using the proper assertion method instead of the problematic called_once_with attribute.

✨ Finishing Touches

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• Commit unit tests in branch fix/tests_fails_in_python3.12

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[codecov]

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✅ All modified and coverable lines are covered by tests.

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