Add PureJSON renderer (#694)

Closes #693

context_17_test.go

@@ -0,0 +1,27 @@
+// Copyright 2018 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+// +build go1.7
+
+package gin
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Tests that the response is serialized as JSON
+// and Content-Type is set to application/json
+// and special HTML characters are preserved
+func TestContextRenderPureJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+	c.PureJSON(http.StatusCreated, H{"foo": "bar", "html": "<b>"})
+	assert.Equal(t, http.StatusCreated, w.Code)
+	assert.Equal(t, "{\"foo\":\"bar\",\"html\":\"<b>\"}\n", w.Body.String())
+	assert.Equal(t, "application/json; charset=utf-8", w.HeaderMap.Get("Content-Type"))
+}