Unit Tests for post_modal

[VertikaBajpai]

This change included the Unittest for post_modal widget.

Issue Number: #2150
Fixed: #2150

Did you add tests for your changes?

Yes

Summary

It is unit test for post_modal widget.

Does this PR introduce a breaking change?

No, this does not introduce any major changes to the codebase.

Have you read the contributing guide?

Yes, I have read and followed the guidelines.

[github-actions]

Our Pull Request Approval Process

We have these basic policies to make the approval process smoother for our volunteer team.

Testing Your Code

Please make sure your code passes all tests. Our test code coverage system will fail if either of these two conditions occur:

1. The overall code coverage drops below the target threshold of the repository
2. Any file in the pull request has code coverage levels below the repository threshold

The process helps maintain the overall reliability of the code base and is a prerequisite for getting your PR approved. Assigned reviewers regularly review the PR queue and tend to focus on PRs that are passing.

Reviewers

When your PR has been assigned reviewers contact them to get your code reviewed and approved via:

1. comments in this PR or
2. our slack channel

Reviewing Your Code

Your reviewer(s) will have the following roles:

1. arbitrators of future discussions with other contributors about the validity of your changes
2. point of contact for evaluating the validity of your work
3. person who verifies matching issues by others that should be closed.
4. person who gives general guidance in fixing your tests

Other

🎯 Please be considerate of our volunteers' time. Contacting the person who assigned the reviewers is not advised unless they ask for your input. Do not @ the person who did the assignment otherwise.

[github-actions]

Congratulations on making your first PR! 🎊 If you haven't already, check out our Contributing Guidelines and PR Reporting Guidelines to ensure that you are following our guidelines for contributing and creating PR.

[palisadoes]

1. Closing. There are too many files in this PR.
2. This is a flutter app, and yet you are submitting Node.js files
3. Please fix this.