Request for Writing Unit Tests for Existing Models and Functions

I would like to request the addition of unit tests for the existing models and functions in the djangoessential library. Having comprehensive unit tests is crucial for ensuring the reliability and stability of the codebase, particularly when making future changes or adding new features.

The unit tests should cover the following aspects:

- Validation of model fields, ensuring that required fields are properly validated.
- Testing custom methods and business logic defined within the models to ensure they behave as expected.
- Testing individual functions to verify their outputs against various inputs, including edge cases.
- Ensuring the integrity of relationships between models, such as ForeignKey, OneToOne, and ManyToMany fields.
- Testing model constraints, such as unique fields, default values, and custom validations.

Writing these tests will not only improve code quality but also provide a safety net for future development and refactoring.