fix regression introduced in v3.6.0 with string urls (#62)

* fix regression introduced in v3.6.0 with string urls

* Avoid a useless Object.assign()

Author: mcollina

index.js

@@ -100,7 +100,12 @@ function doInject (dispatchFunc, options, callback) {
 }
 
 function Chain (dispatch, option) {
-  this.option = Object.assign({}, option)
+  if (typeof option === 'string') {
+    this.option = { url: option }
+  } else {
+    this.option = Object.assign({}, option)
+  }
+
   this.dispatch = dispatch
   this._hasInvoked = false
   this._promise = null

test/test.js

@@ -1198,6 +1198,20 @@ test('chainable api: invoking end method multiple times should throw', (t) => {
   t.throws(() => chain.end(), Error)
 })
 
+test('chainable api: string url', (t) => {
+  t.plan(2)
+
+  function dispatch (req, res) {
+    res.writeHead(200, { 'Content-Type': 'text/plain' })
+    res.end()
+    t.pass()
+  }
+
+  const chain = inject(dispatch, 'http://example.com:8080/hello')
+
+  chain.then(() => t.pass())
+})
+
 test('Response.json() should parse the JSON payload', (t) => {
   t.plan(2)