test: create reusable test fixtures and mock data

[Abd-Standard]

Description

Refactor the existing test suite by introducing reusable fixtures and mock data for common testing scenarios. This will reduce duplicated setup code and improve test readability and maintainability.

Acceptance Criteria
Shared fixtures created
Duplicate setup removed
Existing tests updated
Documentation included

[Ayinkx]

Hi i would like to work on this issue please assign to me
I can do it perfectly

[Ayinkx01]

Hi l would like to take this job

[DavisVT]

i'm a developer well fit for implementing this task
Kindly assign them to me

[DavisVT]

i'm a developer well fit for implementing this task
Kindly assign them to me

[grantfox-oss]

🦊 GrantFox — @DavisVT has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #48)
2. Your PR will be reviewed by the Core-Foundry maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@DavisVT's PR #137 was approved and merged by @Abd-Standard.

🏆 @DavisVT: You earned 40 FoxPoints for this contribution! Your current tier: Builder (1,734 total points). Track your full progress on GrantFox.

👏 Great work, @DavisVT! Keep contributing to Core-Foundry.