demonstrate fetch tar extract errors with chunked encoding.

Related to npm/cli#3884, npm/make-fetch-happen#63

npm v7+ throws integrity and zlib corrupted errors when installing from
a registry that uses chunked encoding.

This package reproduces that error using make-fetch-happen and tar. The
error only occurs when fetch is passed integrity and the server uses
chunked encoding. Only the `extract with integirty` test fails.

.gitignore

@@ -0,0 +1,2 @@
+/.nyc_output/
+/node_modules/

error.test.js

@@ -0,0 +1,96 @@
+import crypto from 'crypto'
+import fetch from 'make-fetch-happen'
+import tar from 'tar'
+import fs from 'fs/promises'
+import http from 'http'
+import t from 'tap'
+
+const lodash = await fs.readFile('lodash-4.17.19.tgz')
+const integrity = crypto
+  .createHash('sha512')
+  .update(lodash)
+  .digest('base64')
+
+// different sizes will reproduce the issue, but large sizes will not.
+const size = 0x4000
+
+const server = http.createServer(async (req, res) => {
+  const headers = {}
+  if (req.url === '/content-length') headers['content-length'] = lodash.length
+  res.writeHead(200, headers)
+  for (let i = 0; i < lodash.length; i += size) {
+    res.write(lodash.slice(i, i+size));
+  }
+  res.end()
+})
+
+server.listen(4000, 'localhost')
+await new Promise((resolve, reject) => {
+  server.once('listening', resolve)
+  server.once('error', reject)
+})
+console.log(server.address())
+t.teardown(() => server.close())
+
+await t.test('res.body data events updating hash', async t => {
+  const res = await fetch('http://localhost:4000', { integrity })
+  const hash = crypto.createHash('sha512')
+  await new Promise((resolve,reject) => {
+    res.body.on('end', resolve)
+    res.body.on('error', reject)
+    res.body.on('data', data => hash.update(data))
+  })
+
+  t.equal(hash.digest('base64'), integrity, 'yields the right digest')
+})
+
+await t.test('res.body pipe to createHash', async t => {
+  const res = await fetch('http://localhost:4000', { integrity })
+  const hash = crypto.createHash('sha512')
+  await new Promise((resolve,reject) => {
+    // XXX Hash doesn't emit end?
+    // hash.on('end', resolve)
+    res.body.on('end', resolve)
+    hash.on('error', reject)
+    res.body.on('error', reject)
+    res.body.pipe(hash)
+  })
+
+  t.equal(hash.digest('base64'), integrity, 'yields the right digest')
+})
+
+await t.test('extract with integrity', async t => {
+  const dest = t.testdir()
+  const res = await fetch('http://localhost:4000', { integrity })
+
+  await extract(res.body, dest)
+  t.pass('succeeds')
+})
+
+await t.test('extract with integrity and content-length', async t => {
+  const dest = t.testdir()
+  const res = await fetch('http://localhost:4000/content-length', { integrity })
+
+  await extract(res.body, dest)
+  t.pass('succeeds')
+})
+
+await t.test('extract without integrity', async t => {
+  const dest = t.testdir()
+  const res = await fetch('http://localhost:4000')
+
+  await extract(res.body, dest)
+  t.pass('succeeds')
+})
+
+async function extract (stream, dest) {
+  // copied from pacote
+  // https://github.com/npm/pacote/blob/bd67be1ea53ab02c2be781a3fc2283eb9fcba3c8/lib/fetcher.js#L399-L419
+  const extractor = tar.x({ cwd: dest })
+  return new Promise((resolve, reject) => {
+    extractor.on('end', resolve)
+    extractor.on('error', reject)
+    stream.on('error', reject)
+    stream.pipe(extractor)
+  })
+}