fix: InterceptedRequestRouter.handleWrite arity issue (#2371)

.eslintrc.yml

@@ -27,6 +27,9 @@ rules:
   # TODO These are included in standard and should be cleaned up and turned on.
   n/no-deprecated-api: 'off' # we still make heavy use of url.parse
 
+  # TODO remove once we drop support for Node 10
+  node/no-deprecated-api: 'off'
+
   # Nock additions.
   strict: ['error', 'safe']
   no-console: 'error'

lib/intercepted_request_router.js

@@ -143,8 +143,11 @@ class InterceptedRequestRouter {
 
   // from docs: When write function is called with empty string or buffer, it does nothing and waits for more input.
   // However, actually implementation checks the state of finished and aborted before checking if the first arg is empty.
-  handleWrite(buffer, encoding, callback) {
+  handleWrite(...args) {
     debug('request write')
+
+    let [buffer, encoding] = args
+
     const { req } = this
 
     if (req.finished) {
@@ -171,6 +174,9 @@ class InterceptedRequestRouter {
     }
     this.requestBodyBuffers.push(buffer)
 
+    // writable.write encoding param is optional
+    // so if callback is present it's the last argument
+    const callback = args.length > 1 ? args[args.length - 1] : undefined
     // can't use instanceof Function because some test runners
     // run tests in vm.runInNewContext where Function is not same
     // as that in the current context

tests/test_request_overrider.js

@@ -89,6 +89,40 @@ describe('Request Overrider', () => {
     })
   })
 
+  it('write callback called when encoding is not supplied', done => {
+    const scope = nock('http://example.test')
+      .filteringRequestBody(/mia/, 'nostra')
+      .post('/', 'mamma nostra')
+      .reply()
+
+    const reqWriteCallback = sinon.spy()
+
+    const req = http.request(
+      {
+        host: 'example.test',
+        method: 'POST',
+        path: '/',
+        port: 80,
+      },
+      res => {
+        expect(reqWriteCallback).to.have.been.calledOnce()
+        expect(res.statusCode).to.equal(200)
+        res.on('end', () => {
+          scope.done()
+          done()
+        })
+        // Streams start in 'paused' mode and must be started.
+        // See https://nodejs.org/api/stream.html#stream_class_stream_readable
+        res.resume()
+      }
+    )
+
+    req.write('mamma mia', () => {
+      reqWriteCallback()
+      req.end()
+    })
+  })
+
   it('write callback is not called if the provided chunk is undefined', done => {
     const scope = nock('http://example.test').post('/').reply()
 
@@ -117,6 +151,34 @@ describe('Request Overrider', () => {
     req.end()
   })
 
+  it("write doesn't throw if invoked w/o callback", done => {
+    const scope = nock('http://example.test').post('/').reply()
+
+    const reqWriteCallback = sinon.spy()
+
+    const req = http.request(
+      {
+        host: 'example.test',
+        method: 'POST',
+        path: '/',
+      },
+      res => {
+        expect(res.statusCode).to.equal(200)
+        res.on('end', () => {
+          expect(reqWriteCallback).to.not.have.been.called()
+          scope.done()
+          done()
+        })
+        // Streams start in 'paused' mode and must be started.
+        // See https://nodejs.org/api/stream.html#stream_class_stream_readable
+        res.resume()
+      }
+    )
+
+    req.write(undefined)
+    req.end()
+  })
+
   it('end callback called', done => {
     const scope = nock('http://example.test')
       .filteringRequestBody(/mia/, 'nostra')