Add Assertion Skill

Add a new assertion function to bashunit following strict TDD methodology.

Prerequisites

1. Task file must exist — create .tasks/YYYY-MM-DD-add-assertion-name.md
2. Study patterns — read tests/unit/assert_test.sh and src/assertions.sh

Workflow

1. Plan

Ask user: assertion name, parameters, success/failure behavior, error messages.

Document acceptance criteria and test inventory in task file.

2. Study Existing Patterns

Read src/assertions.sh and tests/unit/assert_test.sh to understand:

• Parameter validation, assertion logic, error message format
• Return codes (0 = success, 1 = failure)
• How tests verify both success and failure cases

3. TDD Cycles

For each test in inventory, follow RED -> GREEN -> REFACTOR:

1. Basic success case — assertion passes with valid input
2. Failure case — assertion fails correctly: capture its output and compare it with bashunit::console_results::print_failed_test (there is no assert_fails)
3. Edge cases — empty input, special characters, nested structures, malformed data

4. Integration

• Source new file in src/bashunit.sh if created
• export -f the assertion function
• Run full test suite: ./bashunit tests/
• Quality checks: make sa && make lint

5. Documentation

• Add function header with Arguments/Returns/Example
• Update CHANGELOG.md
• Update user-facing docs if applicable

Final Checklist

• All tests passing (success, failure, edge cases)
• Function documented and exported
• Quality gate passes
• CHANGELOG updated
• Task file completed