tests/issue-31_enlarging_test_coverage enlarged tests coverage

Type of change

• Bug Fix
• Feature
• Tests

Does this introduce a change in the core logic?

• [No]

Does this introduce a change in the cloud provider implementation, and if so which cloud?

• AWS
• Azure
• GCP
• IBM

Does this introduce a change that must be documented in the README.md file?

• [No]

Updates description?

Describe your code changes in detail for reviewers (links on Gitlab issues, etc.)

• Test refactoring
• Increased test coverage from 139 to 490 tests
• Added information on execution and structure of tests in README