Add integration tests for P2P library - Closes #1068

[jondubois]

What was the problem?

Missing integration tests.

How did I fix it?

• Implemented integration test cases.
• Fixed some bugs which were uncovered by the new test cases.

How to test it?

npm run test:integration

Review checklist

• The PR resolves #1068
• All new code is covered with unit tests
• All new code was formatted with Prettier
• Linting passes
• Tests pass
• Commit messages follow the commit guidelines
• Documentation has been added/updated

[jondubois]

Rebased to fix conflicts.