Migrate test suite from JUnit 4 to JUnit 5 - Fixed build issues with JEPTest migration

[Copilot]

This PR implements the migration from JUnit 4 to JUnit 5 for the test suite, establishing a proven migration workflow and successfully migrating test classes while resolving critical build issues.

Changes Made

Fixed Build Issues

Resolved critical build failure caused by incomplete JUnit 5 migration in JEPTest class:

• Removed conflicting extends TestCase inheritance that violated JUnit 5 constraints
• Eliminated duplicate constructor causing "must declare a single constructor" error
• Updated main method to use default constructor pattern
• Completed migration to pure JUnit 5 implementation

JUnit 5 Dependencies

Updated pom.xml to include JUnit 5 Jupiter dependencies alongside existing JUnit 4:

• junit-jupiter-api 5.11.1 - JUnit 5 API for test annotations and assertions
• junit-jupiter-engine 5.11.1 - JUnit 5 test execution engine
• Maintained junit-vintage-engine 5.11.1 for backward compatibility with JUnit 4 tests

Successfully Migrated Test Classes

Three test classes have been fully migrated to JUnit 5:

• LogarithmTest - Complete migration with JUnit 5 assertions
• NaturalLogarithmTest - Complete migration with JUnit 5 assertions
• JEPTest - Complete migration resolving build constraint violations

Migration Pattern

The proven migration workflow:

1. Replace JUnit 4 imports with JUnit 5 equivalents
2. Remove extends TestCase inheritance
3. Use single default constructor
4. Add @Test annotations to test methods
5. Add @BeforeEach for setup methods
6. Replace Assert.* with Assertions.* calls

Test Results

• Before: Build failing with JUnit 5 constructor constraint violations
• After: 201 tests passing, zero failures or errors
• All existing JUnit 4 tests continue running via Vintage engine
• New JUnit 5 tests run via Jupiter engine
• Full backward compatibility maintained

The build now succeeds completely with all functionality validated through both basic and advanced example execution.

Addressing #9.

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[nathanfunk]

@copilot - please address the remaining build issues

[Copilot]

@copilot - please address the remaining build issues

Fixed the build issues by completing the migration of JEPTest to JUnit 5. The class had conflicting JUnit 4 and 5 patterns causing a constructor constraint violation. Removed the extends TestCase inheritance, eliminated the duplicate constructor, and updated the main method. All tests now pass (201 tests, 0 failures). Commit: 380c832