test: add pagination total capping regression test

Author: thegreatalxx

test/unit/app/utils/pagination.spec.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest'
+
+/**
+ * Tests for the pagination total capping logic used in search.vue.
+ *
+ * The search page caps the displayed pagination total to EAGER_LOAD_SIZE
+ * so that page links only reflect pages that can actually be fetched.
+ * Without the cap, a search returning total=92,000 items would show 3,680
+ * pages at 25 items/page, but navigation beyond page 20 silently fails.
+ */
+
+const EAGER_LOAD_SIZE = { algolia: 500, npm: 500 } as const
+
+function paginationTotal(
+  effectiveTotal: number,
+  provider: keyof typeof EAGER_LOAD_SIZE,
+): number {
+  const cap = EAGER_LOAD_SIZE[provider]
+  return Math.min(effectiveTotal, cap)
+}
+
+describe('paginationTotal capping logic', () => {
+  it('returns the total as-is when it is below the cap', () => {
+    expect(paginationTotal(100, 'npm')).toBe(100)
+    expect(paginationTotal(100, 'algolia')).toBe(100)
+  })
+
+  it('returns the cap when the total exceeds it', () => {
+    expect(paginationTotal(92_000, 'npm')).toBe(500)
+    expect(paginationTotal(92_000, 'algolia')).toBe(500)
+  })
+
+  it('returns exactly the cap when the total equals the cap', () => {
+    expect(paginationTotal(500, 'npm')).toBe(500)
+    expect(paginationTotal(500, 'algolia')).toBe(500)
+  })
+
+  it('returns 0 when total is 0', () => {
+    expect(paginationTotal(0, 'npm')).toBe(0)
+  })
+
+  it('caps algolia and npm identically (both have 500 limit)', () => {
+    const total = 10_000
+    expect(paginationTotal(total, 'algolia')).toBe(paginationTotal(total, 'npm'))
+  })
+
+  it('page count derived from capped total stays within fetchable range', () => {
+    const pageSize = 25
+    const rawTotal = 92_000
+    const cappedTotal = paginationTotal(rawTotal, 'npm')
+    const maxPages = Math.ceil(cappedTotal / pageSize)
+    // Should be 20 pages (500 / 25), not 3680 (92000 / 25)
+    expect(maxPages).toBe(20)
+  })
+})