move stream readable check test to http.js and update readme file

README.md

@@ -111,6 +111,10 @@ This error will occur when the given stream has an encoding set on it, making it
 a decoded stream. The stream should not have an encoding set and is expected to
 emit `Buffer` objects.
 
+#### stream.not.readable
+
+This error will occur when the given stream not readable, it may be a request parsed by other middleware before.
+
 ## Examples
 
 ### Simple Express example

index.js

@@ -173,8 +173,10 @@ function readStream (stream, encoding, length, limit, callback) {
     }))
   }
 
-  if (stream.hasOwnProperty('readable') && !stream.readable) {
-    return done(createError(500, 'stream should be readable'))
+  if (typeof stream.readable !== 'undefined' && !stream.readable) {
+    return done(createError(500, 'stream should be readable', {
+      type: 'stream.not.readable'
+    }))
   }
 
   var received = 0

test/http.js

@@ -67,6 +67,28 @@ describe('using http streams', function () {
     })
   })
 
+  it('should throw if stream is not readable', function (done) {
+    var server = http.createServer(function onRequest (req, res) {
+      getRawBody(req, { length: req.headers['content-length'] }, function (err) {
+        assert.ifError(err)
+
+        getRawBody(req, { length: req.headers['content-length'] }, function (err) {
+          assert.ok(err)
+          assert.equal(err.status, 500)
+          assert.equal(err.type, 'stream.not.readable')
+          assert.equal(err.message, 'stream should be readable')
+          done()
+        })
+      })
+    })
+
+    server.listen(function onListen () {
+      var addr = server.address()
+      var client = http.request({method: 'POST', port: addr.port})
+      client.end('hello, world!')
+    })
+  })
+
   it('should throw if connection ends', function (done) {
     var socket
     var server = http.createServer(function onRequest (req, res) {

test/index.js

@@ -112,17 +112,6 @@ describe('Raw Body', function () {
     })
   })
 
-  it('should throw if stream is not readable', function (done) {
-    var stream = new Readable()
-    stream.readable = false
-
-    getRawBody(stream, function (err, buf) {
-      assert.equal(err.status, 500)
-      assert.equal(err.message, 'stream should be readable')
-      done()
-    })
-  })
-
   it('should work with an empty stream', function (done) {
     var stream = new Readable()
     stream.push(null)