test: add performance benchmarks for transformation speed and memory usage

Author: KeJunMao

test/performance.bench.ts

@@ -0,0 +1,29 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { bench, describe } from 'vitest'
+import { Context, ifDirective, includeDirective, MessageDirective, theDefineDirective } from '../src'
+
+describe('benchmark', () => {
+  const root = resolve(__dirname, './fixtures')
+
+  const context = new Context({
+    directives: [ifDirective, theDefineDirective, includeDirective, MessageDirective],
+    cwd: root,
+  })
+
+  bench('transform simple code', () => {
+    const code = `
+      #define DEV 1
+      #if DEV
+        console.log('development')
+      #endif
+    `
+    context.transform(code, 'test.js')
+  })
+
+  bench('transform complex code', () => {
+    const code = readFileSync(resolve(root, 'include-main.txt'), 'utf-8')
+
+    context.transform(code, 'test.js')
+  })
+})

test/preformance.test.ts

@@ -0,0 +1,47 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { describe, expect, it } from 'vitest'
+import {
+  Context,
+  ifDirective,
+  includeDirective,
+  MessageDirective,
+  theDefineDirective,
+} from '../src'
+
+describe('performance', () => {
+  const root = resolve(__dirname, './fixtures')
+
+  const context = new Context({
+    directives: [ifDirective, theDefineDirective, includeDirective, MessageDirective],
+    cwd: root,
+  })
+
+  it.skip('should transform quickly', () => {
+    const code = readFileSync(resolve(root, 'include-main.txt'), 'utf-8')
+
+    const start = performance.now()
+    for (let i = 0; i < 100; i++) {
+      context.transform(code, 'test.js')
+    }
+    const end = performance.now()
+    const duration = end - start
+
+    // Expect it to take less than 100ms for 100 transforms
+    expect(duration).toBeLessThan(100)
+  })
+
+  it.skip('should not consume excessive memory', () => {
+    const code = readFileSync(resolve(root, 'include-main.txt'), 'utf-8')
+
+    const initialMemory = process.memoryUsage().heapUsed
+    for (let i = 0; i < 10000; i++) {
+      context.transform(code, 'test.js')
+    }
+    const finalMemory = process.memoryUsage().heapUsed
+    const memoryIncrease = finalMemory - initialMemory
+
+    // Expect memory increase to be less than 10MB
+    expect(memoryIncrease).toBeLessThan(10 * 1024 * 1024)
+  })
+})