Strengthen test with data provider

Generate assertions for new respond statement

fix: mismatched key casing (laravel-shift#70)

Add support for Laravel 7 and PHPUnit 9

Ensure all generated directories exist

Apply fixes from StyleCI

Use fixture name consistently

Strengthen factory generator tests

Merge pull request laravel-shift#57 from laravel-shift/model-properties

Add PHPDoc for properties of Model class

Merge pull request laravel-shift#48 from nathane/feature/change-id-co…

…lumn-datatype-to-bigincrements

Fix the migration datatype of an `id` column