perf: optimize out jest.exodus and expect from bundles if not used

Author: ChALkeR

bundler/bundle.js

@@ -224,6 +224,7 @@ export const build = async (...files) => {
     await importSource('./modules/globals.cjs')
   }
 
+  const haveJestAPIs = { expect: false, exodus: false }
   if (options.jest) {
     const { jestConfig } = options
     const preload = [...(jestConfig.setupFiles || []), ...(jestConfig.setupFilesAfterEnv || [])]
@@ -244,6 +245,14 @@ export const build = async (...files) => {
 
     // copy of loader/jest
     input.push(`await (await import(${stringify(resolveSrc('jest.setup.js'))})).setupJest();`)
+
+    const ignoreFrom = /\/test\/src\/(jest(\.(mock|snapshot))?\.js|engine\.pure\.cjs|expect\.cjs)$/u // rechecked to not use those apis if no outside usage
+    specificLoadPipeline.push(async (source, filepath) => {
+      if (ignoreFrom.test(filepath.replaceAll('\\', '/'))) return source
+      haveJestAPIs.expect ||= /(^|[^#])\bexpect([(.]|$)/mu.test(source)
+      haveJestAPIs.exodus ||= /jest\.exodus/u.test(source)
+      return source
+    })
   }
 
   for (const file of files) importFile(file)
@@ -421,6 +430,8 @@ export const build = async (...files) => {
       EXODUS_TEST_FSFILES: stringify(emptyToUndefined(fsfiles)), // TODO: can we safely use relative paths?
       EXODUS_TEST_FSFILES_CONTENTS: stringify(emptyToUndefined([...fsFilesContents.entries()])),
       EXODUS_TEST_FSDIRS: stringify(emptyToUndefined([...fsFilesDirs.entries()])),
+      EXODUS_TEST_LOAD_EXPECT: stringify(haveJestAPIs.expect),
+      EXODUS_TEST_LOAD_JESTEXODUS: stringify(haveJestAPIs.exodus),
     },
     alias: {
       // Jest, tape and node:test
@@ -552,10 +563,22 @@ export const build = async (...files) => {
   let res = await buildWrap(config)
   assert.equal(res instanceof Error, res.errors.length > 0)
 
+  let needRerun = false
   if (fsFilesContents.size > 0 || fsFilesDirs.size > 0) {
     // re-run as we detected that tests depend on fsReadFileSync contents
     config.define.EXODUS_TEST_FSFILES_CONTENTS = stringify([...fsFilesContents.entries()])
     config.define.EXODUS_TEST_FSDIRS = stringify([...fsFilesDirs.entries()])
+    needRerun = true
+  }
+
+  if (haveJestAPIs.expect || haveJestAPIs.exodus) {
+    // re-run as we detected expect or jest.exodus usage and need to bundle those
+    config.define.EXODUS_TEST_LOAD_EXPECT = stringify(haveJestAPIs.expect)
+    config.define.EXODUS_TEST_LOAD_JESTEXODUS = stringify(haveJestAPIs.exodus)
+    needRerun = true
+  }
+
+  if (needRerun) {
     res = await buildWrap(config)
     assert.equal(res instanceof Error, res.errors.length > 0)
   }

src/expect.cjs

@@ -13,21 +13,27 @@ function fixupAssertions() {
 
 function loadExpect(loadReason) {
   if (expect) return expect
-  try {
-    expect = require('expect').expect
-  } catch {
-    throw new Error(`Failed to load 'expect', required for ${loadReason}`)
-  }
+  // eslint-disable-next-line no-undef
+  if (typeof EXODUS_TEST_LOAD_EXPECT !== 'undefined' && EXODUS_TEST_LOAD_EXPECT === false) {
+    if (loadReason === 'jest.mock') return // allow that and ignore if there is no usage
+    throw new Error('FATAL: expect() was optimized out')
+  } else {
+    try {
+      expect = require('expect').expect
+    } catch {
+      throw new Error(`Failed to load 'expect', required for ${loadReason}`)
+    }
 
-  // console.log('expect load reason:', loadReason)
-  try {
-    expect.extend(require('jest-extended'))
-  } catch {}
+    // console.log('expect load reason:', loadReason)
+    try {
+      expect.extend(require('jest-extended'))
+    } catch {}
 
-  for (const x of extend) expect.extend(...x)
-  for (const [key, value] of set) expect[key] = value
-  fixupAssertions()
-  return expect
+    for (const x of extend) expect.extend(...x)
+    for (const [key, value] of set) expect[key] = value
+    fixupAssertions()
+    return expect
+  }
 }
 
 const areNumeric = (...args) => args.every((a) => typeof a === 'number' || typeof a === 'bigint')

src/jest.js

@@ -248,8 +248,9 @@ if (process.env.EXODUS_TEST_PLATFORM !== 'deno' && globalThis.process) {
   }
 }
 
-export const jest = {
-  exodus: {
+// jest.exodus extension
+function makeJestExodus() {
+  return {
     __proto__: null,
     ...exodus,
     mock: {
@@ -265,7 +266,15 @@ export const jest = {
         return globalThis.WebSocket
       },
     },
-  },
+  }
+}
+
+export const jest = {
+  exodus:
+    // eslint-disable-next-line no-undef
+    typeof EXODUS_TEST_LOAD_JESTEXODUS === 'undefined' || EXODUS_TEST_LOAD_JESTEXODUS !== false
+      ? makeJestExodus()
+      : undefined,
   setTimeout: (x) => {
     assert.equal(typeof x, 'number')
     defaultTimeout = x