Build Flutter unit tests (approx 50)

I am looking for a skilled developer to build approximately 50 unit tests for my Flutter App. The ideal candidate should have experience in testing UI components with Flutter. Please share your experience with unit testing in Flutter.
We want to follow the standard unit testing of Flutter, no external frameworks:
https://docs.flutter.dev/cookbook/testing/unit/introduction

The app can be foud in the AppStore, but you can't use it without user credentials, so this is just for the screenshots:
https://apps.apple.com/us/app/food-blocks/id6446424724

We prepared a list of nearly 50 test cases following the Arrange - Act - Assert pattern. We can't post the whole list here, but here is an example:

Test case: Should increase grocery amounts in shopping list when increasing portion in a recipe
- Arrange
-> A plan with one day and one recipe. The recipe contains a step with at least one ingredient.
-> Open the week plan.
-> Open the recipe.
- Act
-> Increase the portion to 1.5x
-> Close the recipe page and open the shopping list.
- Assert
-> The list should contain the 1.5x amount of the original recipe.

Please give me an estimation how long you think this would take / how much it would cost to build unit tests for all test cases.

Required skills:
- Testing UI components for functionality with Flutter
- Good English skills, so that you are sure the won't be any misunderstandings
- Git, Dart

Deadline:
- About a month

Skills and Experience:
- Experience with Flutter and unit testing
- Knowledge of UI components and custom widgets