test: add browse instrumentation helpers

test/server/utils/libraryBrowseInstrumentation.test.js

@@ -0,0 +1,54 @@
+const chai = require('chai')
+const expect = chai.expect
+
+const {
+  createBrowseRequestProfile,
+  finishBrowseRequestProfile
+} = require('../../../server/utils/queries/libraryBrowseInstrumentation')
+
+describe('libraryBrowseInstrumentation', () => {
+  it('records named browse phases and returns a slow-summary payload', () => {
+    const timestamps = [
+      100,
+      110,
+      160,
+      170,
+      200,
+      210,
+      235,
+      240,
+      280,
+      320
+    ]
+
+    const profile = createBrowseRequestProfile({
+      route: 'GET /api/libraries/:id/items',
+      libraryId: 'lib_1',
+      now: () => timestamps.shift()
+    })
+
+    profile.mark('rows:start')
+    profile.mark('rows:end')
+    profile.mark('count:start')
+    profile.mark('count:end')
+    profile.mark('derived:start')
+    profile.mark('derived:end')
+    profile.mark('postprocess:start')
+    profile.mark('postprocess:end')
+
+    const result = finishBrowseRequestProfile(profile, { slowMs: 150 })
+
+    expect(result).to.deep.equal({
+      route: 'GET /api/libraries/:id/items',
+      libraryId: 'lib_1',
+      totalMs: 220,
+      phases: {
+        rows: 50,
+        count: 30,
+        derived: 25,
+        postprocess: 40
+      },
+      isSlow: true
+    })
+  })
+})