add content negotiation feature, add context.ReadYAML and fix https://github.com/kataras/neffos/issues/1#issuecomment-515698536

Former-commit-id: 9753e3e45c7c24788b97814d3ecfb4b03f5ff414

_examples/http_responsewriter/content-negotiation/main_test.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/xml"
+	"io/ioutil"
+	"testing"
+
+	"github.com/kataras/iris/httptest"
+)
+
+func TestContentNegotiation(t *testing.T) {
+	var (
+		expectedJSONResponse = testdata{
+			Name: "test name",
+			Age:  26,
+		}
+		expectedXMLResponse, _ = xml.Marshal(expectedJSONResponse)
+		expectedHTMLResponse   = "<h1>Test Name</h1><h2>Age 26</h2>"
+	)
+
+	e := httptest.New(t, newApp())
+
+	e.GET("/resource").WithHeader("Accept", "application/json").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/json", "utf-8").
+		JSON().Equal(expectedJSONResponse)
+	e.GET("/resource").WithHeader("Accept", "application/xml").WithHeader("Accept-Charset", "iso-8859-7").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/xml", "iso-8859-7").
+		Body().Equal(string(expectedXMLResponse))
+
+	e.GET("/resource2").WithHeader("Accept", "application/json").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/json", "utf-8").
+		JSON().Equal(expectedJSONResponse)
+	e.GET("/resource2").WithHeader("Accept", "application/xml").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/xml", "utf-8").
+		Body().Equal(string(expectedXMLResponse))
+	e.GET("/resource2").WithHeader("Accept", "text/html").
+		Expect().Status(httptest.StatusOK).
+		ContentType("text/html", "utf-8").
+		Body().Equal(expectedHTMLResponse)
+
+	e.GET("/resource3").WithHeader("Accept", "application/json").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/json", "utf-8").
+		JSON().Equal(expectedJSONResponse)
+	e.GET("/resource3").WithHeader("Accept", "application/xml").
+		Expect().Status(httptest.StatusOK).
+		ContentType("application/xml", "utf-8").
+		Body().Equal(string(expectedXMLResponse))
+
+	// test html with "gzip" encoding algorithm.
+	rawGzipResponse := e.GET("/resource3").WithHeader("Accept", "text/html").
+		WithHeader("Accept-Encoding", "gzip").
+		Expect().Status(httptest.StatusOK).
+		ContentType("text/html", "utf-8").
+		ContentEncoding("gzip").
+		Body().Raw()
+
+	zr, err := gzip.NewReader(bytes.NewReader([]byte(rawGzipResponse)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rawResponse, err := ioutil.ReadAll(zr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected, got := expectedHTMLResponse, string(rawResponse); expected != got {
+		t.Fatalf("expected response to be:\n%s but got:\n%s", expected, got)
+	}
+
+}