test: Add Unit test for `EnvironmentServiceImpl`

[AkashBhuiyan]

This is a sub-issue of #13 to add comprehensive unit tests for the EnvironmentServiceImpl.

Test Coverage

• createEnvironment
• updateEnvironment
• getEnvironmentById
• getAllEnvironments
• deleteEnvironment
• getEnvironmentsByCollection (if applicable)
• addVariable / updateVariable / deleteVariable
• Environment variable resolution and merging
• Validation tests (duplicate names, invalid data)
• Mapping Tests

Technical Details

• Framework: JUnit 5 with Mockito
• Assertions: AssertJ
• All dependencies properly mocked
• Comprehensive edge case and error handling coverage

Running Tests

mvn test -Dtest=EnvironmentServiceImplTest

Related

Issue #13 (Parent)

Labels

testing, good first issue, unit-tests