feat: add test files for next issue recommendation

Signed-off-by: Parv Ninama <ninamaparv@gmail.com>

Author: parvninama

.github/scripts/tests/recommendation.test.js

@@ -0,0 +1,92 @@
+// node --test .github/scripts/tests/recommendation.test.js
+
+const assert = require('node:assert/strict');
+const test = require('node:test');
+
+const {
+  computeLevelStepIndices,
+  buildFallbackChain,
+} = require('../shared/core/recommendation');
+
+const {
+  adjustEligibilityForCurrentPR,
+} = require('../shared/core/eligibility');
+
+const { CONFIG } = require('../shared/config');
+
+// ---------------------------------------------------------------------------
+// computeLevelStepIndices
+// ---------------------------------------------------------------------------
+
+test('computeLevelStepIndices prefers level up, same, then level down', () => {
+  const result = computeLevelStepIndices('beginner', 'intermediate');
+
+  // beginner=1, intermediate=2
+  assert.deepEqual(result, [2, 1]);
+});
+
+test('computeLevelStepIndices falls back to same and lower level', () => {
+  const result = computeLevelStepIndices('intermediate', 'intermediate');
+
+  // intermediate=2, beginner=1
+  assert.deepEqual(result, [2, 1]);
+});
+
+test('computeLevelStepIndices never recommends gfi as fallback', () => {
+  const result = computeLevelStepIndices('beginner', 'beginner');
+
+  // beginner only (no gfi fallback)
+  assert.deepEqual(result, [1]);
+});
+
+// ---------------------------------------------------------------------------
+// buildFallbackChain
+// ---------------------------------------------------------------------------
+
+test('buildFallbackChain expands levels across repos in priority order', () => {
+  const chain = buildFallbackChain('beginner', 'intermediate');
+
+  assert.ok(chain.length > 0);
+
+  // First recommendation should be intermediate in home repo
+  assert.equal(chain[0].levelKey, 'intermediate');
+
+  // Ensure no gfi recommendations exist
+  const hasGfi = chain.some(entry => entry.levelKey === 'gfi');
+  assert.equal(hasGfi, false);
+});
+
+// ---------------------------------------------------------------------------
+// adjustEligibilityForCurrentPR
+// ---------------------------------------------------------------------------
+
+test('adjustEligibilityForCurrentPR bumps eligibility after completing current level', () => {
+  const adjusted = adjustEligibilityForCurrentPR('gfi', 'gfi');
+
+  assert.equal(adjusted, 'beginner');
+});
+
+test('adjustEligibilityForCurrentPR does not downgrade higher eligibility', () => {
+  const adjusted = adjustEligibilityForCurrentPR(
+    'beginner',
+    'advanced',
+  );
+
+  assert.equal(adjusted, 'advanced');
+});
+
+// ---------------------------------------------------------------------------
+// basic integration-style recommendation flow
+// ---------------------------------------------------------------------------
+
+test('fallback chain includes repos for eligible levels only', () => {
+  const chain = buildFallbackChain('intermediate', 'advanced');
+
+  const validLevels = new Set(CONFIG.skillHierarchy);
+
+  for (const entry of chain) {
+    assert.ok(validLevels.has(entry.levelKey));
+    assert.ok(entry.repoConfig.owner);
+    assert.ok(entry.repoConfig.repo);
+  }
+});