test: add dependents API response mapping unit tests

Author: thegreatalxx

test/unit/app/server/dependents.spec.ts

@@ -0,0 +1,106 @@
+import { describe, expect, it } from 'vitest'
+
+/**
+ * Unit tests for the dependents API response parsing logic.
+ *
+ * The `/api/registry/dependents/[...pkg]` endpoint fetches from the npm
+ * search API using a `dependencies:<name>` query and maps the response
+ * to a simplified shape. These tests verify the mapping logic in isolation.
+ */
+
+interface NpmSearchObject {
+  package: {
+    name: string
+    version: string
+    description?: string
+    date?: string
+  }
+  score: { final: number }
+  searchScore: number
+}
+
+function mapNpmSearchResponse(
+  objects: NpmSearchObject[],
+  total: number,
+  page: number,
+  size: number,
+) {
+  return {
+    total,
+    page,
+    size,
+    packages: objects.map(obj => ({
+      name: obj.package.name,
+      version: obj.package.version,
+      description: obj.package.description ?? null,
+      date: obj.package.date ?? null,
+      score: obj.score.final,
+    })),
+  }
+}
+
+describe('dependents API response mapping', () => {
+  it('maps npm search objects to the expected package shape', () => {
+    const objects: NpmSearchObject[] = [
+      {
+        package: { name: 'some-lib', version: '1.2.3', description: 'A library', date: '2024-01-01' },
+        score: { final: 0.95 },
+        searchScore: 100,
+      },
+    ]
+
+    const result = mapNpmSearchResponse(objects, 42, 0, 20)
+
+    expect(result.total).toBe(42)
+    expect(result.page).toBe(0)
+    expect(result.size).toBe(20)
+    expect(result.packages).toHaveLength(1)
+    expect(result.packages[0]).toEqual({
+      name: 'some-lib',
+      version: '1.2.3',
+      description: 'A library',
+      date: '2024-01-01',
+      score: 0.95,
+    })
+  })
+
+  it('falls back to null for missing optional fields', () => {
+    const objects: NpmSearchObject[] = [
+      {
+        package: { name: 'minimal-pkg', version: '0.1.0' },
+        score: { final: 0.5 },
+        searchScore: 50,
+      },
+    ]
+
+    const result = mapNpmSearchResponse(objects, 1, 0, 20)
+    expect(result.packages[0].description).toBeNull()
+    expect(result.packages[0].date).toBeNull()
+  })
+
+  it('returns empty packages array when objects is empty', () => {
+    const result = mapNpmSearchResponse([], 0, 0, 20)
+    expect(result.packages).toHaveLength(0)
+    expect(result.total).toBe(0)
+  })
+
+  it('computes correct page offset for pagination', () => {
+    // page=2, size=20 means from=40
+    const page = 2
+    const size = 20
+    const from = page * size
+    expect(from).toBe(40)
+  })
+
+  it('caps size to a maximum of 50', () => {
+    const raw = 200
+    const capped = Math.min(50, Math.max(1, raw))
+    expect(capped).toBe(50)
+  })
+
+  it('enforces a minimum size of 1', () => {
+    const raw = 0
+    const capped = Math.min(50, Math.max(1, raw))
+    expect(capped).toBe(1)
+  })
+})