Add benchmark

src/utils.bench.ts

@@ -0,0 +1,47 @@
+import { bench, describe } from 'vitest'
+import type { StringChange } from './types'
+import { spliceChangesIntoString } from './utils'
+
+describe('spliceChangesIntoString', () => {
+  // 44 bytes
+  let strTemplate = 'the quick brown fox jumps over the lazy dog '
+  let changesTemplate: StringChange[] = [
+    { start: 10, end: 15, before: 'brown', after: 'purple' },
+    { start: 4, end: 9, before: 'quick', after: 'slow' },
+  ]
+
+  function buildFixture(repeatCount: number, changeCount: number) {
+    // A large set of changes across random places in the string
+    let indxes = new Set(
+      Array.from({ length: changeCount }, (_, i) =>
+        Math.ceil(Math.random() * repeatCount),
+      ),
+    )
+
+    let changes: StringChange[] = Array.from(indxes).flatMap((idx) => {
+      return changesTemplate.map((change) => ({
+        start: change.start + strTemplate.length * idx,
+        end: change.end + strTemplate.length * idx,
+        before: change.before,
+        after: change.after,
+      }))
+    })
+
+    return [strTemplate.repeat(repeatCount), changes] as const
+  }
+
+  let [strSmall, changesSmall] = buildFixture(10, 5)
+  bench('small string', () => {
+    spliceChangesIntoString(strSmall, changesSmall)
+  })
+
+  let [strMedium, changesMedium] = buildFixture(1_000, 50)
+  bench('medium string', () => {
+    spliceChangesIntoString(strMedium, changesMedium)
+  })
+
+  let [strLarge, changesLarge] = buildFixture(100_000, 7_000)
+  bench('large string', () => {
+    spliceChangesIntoString(strLarge, changesLarge)
+  })
+})