fix: make skill assessment MCQ-only

[Zubbee18]

Summary

Converts the skill assessment from a mixed MCQ + text format to purely MCQ-based questions.

Changes

• Question mix: 16 primary MCQs + 2 probe MCQs per direction (above/below) = 20 total
  • Previously: 13 MCQ + 3 text + 1 MCQ/1 text per probe direction
• Scoring: Pure MCQ scoring (correct / total × 100) replaces the previous weighted system (40% MCQ / 60% text)
• Removed AI rubric scoring: RubricScoringService is no longer injected or used for skill assessments (still used by advanced assessments)
• AI question generation: Only generates MCQs when the bank is short; no longer generates text questions for skill assessments
• Removed unused methods: toWeightedSectionScore, extractStrongCompetencies, extractWeakCompetencies, resolveScoredCompetencies
• Updated tests: All 22 unit tests pass with the new MCQ-only structure

Summary by CodeRabbit

• Bug Fixes

  • Updated skill assessment scoring logic to function exclusively with multiple-choice questions.

• Refactor

  • Revised assessment question generation and selection to support MCQ-only format.
  • Simplified competency reporting to reflect updated evaluation methodology.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

This PR refactors skill assessment to eliminate text-question and rubric-scoring logic entirely. The service now uses MCQ-only evaluation for submission, scoring, and reporting. Tests are updated with MCQ-only fixtures and scoring scenarios, and text-related helpers and dependencies are removed.

Changes

MCQ-only assessment conversion

Layer / File(s)	Summary
Dependencies and imports cleanup src/modules/talent/assessment/skill-assessment.service.ts, src/modules/talent/assessment/skill-assessment.service.spec.ts	RubricScoringService dependency is removed from constructor wiring; text-length-validation imports and mock declarations are eliminated.
Assessment submission and MCQ-only scoring src/modules/talent/assessment/skill-assessment.service.ts	submit() now evaluates each question via scoreGeneratedMcq without text-rubric batching; raw_score/max_score are set from correctness booleans; total/section scoring and above-probe gates depend only on MCQ counters.
AI question generation for MCQs only src/modules/talent/assessment/skill-assessment.service.ts	ensureSkillQuestionsWithAI() generates only MCQ variants (no parallel text generation); AssessmentQuestion rows are persisted with only MCQ results.
Question-mix selection for MCQ-only src/modules/talent/assessment/skill-assessment.service.ts	selectSkillQuestionMix() and selectSkillProbeMix() select only MCQs and base availability/error checks on MCQ counts; text-question filler is removed.
Guidance report and helper cleanup src/modules/talent/assessment/skill-assessment.service.ts	Guidance report sends empty competency arrays; toWeightedSectionScore, extractStrongCompetencies, and extractWeakCompetencies helpers are removed.
Test fixtures for MCQ-only questions src/modules/talent/assessment/skill-assessment.service.spec.ts	makeSkillBankQuestions() generates only MCQ questions; makeProbeQuestions() includes only MCQ items; question-type assertions in start() tests are adjusted.
Test cases for MCQ scoring logic src/modules/talent/assessment/skill-assessment.service.spec.ts	New test asserts failure when all primary MCQ answers are wrong; below-50% scenario is rewritten with two MCQ questions and updated mocks; text-length-validation test is replaced with a scenario validating correct MCQ scoring when the majority of answers are correct.

🎯 4 (Complex) | ⏱️ ~75 minutes

Possibly related PRs

• hngprojects/skill-bridge-api#155: Both PRs modify guidance-report generation—this PR changes SkillAssessmentService to perform MCQ-only scoring and feed empty competency data into guidance generation, while the other PR adjusts AI/guidance services to compute competency ratings based on the assessment input data.

Suggested labels

bug, enhancement

Suggested reviewers

• Trojanhorse7
• kenneropia

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title accurately summarizes the main objective: converting skill assessment from a mixed MCQ + text format to purely MCQ-based questions.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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