Added support for Server Side events

Signed-off-by: Roshan Patil <[email protected]>

README.md

@@ -33,6 +33,7 @@ Built with Go - Mmock runs without installation on multiple platforms.
 * Public interface auto discover
 * Lightweight and portable
 * No installation required
+* Server Side Events
 
 ### Example
 
@@ -236,7 +237,7 @@ See https://pkg.go.dev/regexp/syntax for regexp syntax
 * *statusCode*: Response status code
 * *headers*: Array of headers. It allows more than one value for the same key and vars.
 * *cookies*: Array of cookies. It allows vars.
-* *body*: Body string. It allows vars.
+* *body*: Body string. It allows vars. For SSE, pass the body in array of JSON format.
 
 #### Callback (Optional)
 
@@ -631,6 +632,8 @@ You can always disable this behavior adding the following flag `-server-statisti
 - Improved logging with levels thanks to [@jcdietrich](https://github.com/jcdietrich) [@jdietrich-tc](https://github.com/jdietrich-tc)
 - Support for Regular Expressions for QueryStringParameters [@jcdietrich](https://github.com/jcdietrich) [@jdietrich-tc](https://github.com/jdietrich-tc)
 - Support for URI and Description tags [@jcdietrich](https://github.com/jcdietrich) [@jdietrich-tc](https://github.com/jdietrich-tc)
+- Support for Server Side Events [@rosspatil](https://github.com/rosspatil)
+
 
 ### Contributing
 

config/sse.yaml

@@ -0,0 +1,42 @@
+request:
+  method: POST
+  path: /events
+response:
+  statusCode: 200
+  headers:
+    Content-Type:
+      - "text/event-stream"
+    Connection:
+      - "keep-alive"
+    Cache-Control:
+      - "no-cache"
+  body: >
+    [
+      {  
+        "test":"1"
+      },
+      {  
+        "test":"2"
+      },
+      {  
+        "test":"3"
+      },
+      {  
+        "test":"4"
+      },
+      {  
+        "test":"5"
+      },
+      {  
+        "test":"6"
+      },
+      {  
+        "test":"7"
+      },
+      {  
+        "test":"8"
+      },
+      {  
+        "test":"9"
+      }
+    ]

internal/server/dispatcher.go

@@ -95,7 +95,7 @@ func (di *Dispatcher) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 
 	//translate request
-	di.Translator.WriteHTTPResponseFromDefinition(transaction.Response, w)
+	di.Translator.WriteHTTPResponseFromDefinition(transaction.Response, w, req)
 
 	if mock.Callback.Url != "" {
 		go func() {

pkg/mock/http.go

@@ -1,11 +1,14 @@
 package mock
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"strings"
+	"time"
+
+	"github.com/tidwall/gjson"
 )
 
 // HTTP is and adaptor beteewn the http and mock config.
@@ -39,7 +42,7 @@ func (t HTTP) BuildRequestDefinitionFromHTTP(req *http.Request) Request {
 		res.QueryStringParameters[name] = values
 	}
 
-	body, _ := ioutil.ReadAll(req.Body)
+	body, _ := io.ReadAll(req.Body)
 	res.Body = string(body)
 
 	return res
@@ -68,22 +71,56 @@ func getHostAndPort(req *http.Request) (string, string) {
 }
 
 // WriteHTTPResponseFromDefinition read a mock response and write a http response.
-func (t HTTP) WriteHTTPResponseFromDefinition(fr *Response, w http.ResponseWriter) {
+func (t HTTP) WriteHTTPResponseFromDefinition(fr *Response, w http.ResponseWriter, req *http.Request) {
+	if isSSE(fr) {
+		streamResponse(fr, w, req)
+		return
+	}
+	addHeadersAndCookies(fr, w)
+	w.WriteHeader(fr.StatusCode)
+	io.WriteString(w, fr.Body)
+}
 
+// Check if the response is of type SSE
+func isSSE(fr *Response) bool {
+	values, ok := fr.Headers["content-type"]
+	if ok {
+		for _, value := range values {
+			return strings.ToLower(value) == "text/event-stream"
+		}
+	}
+	return false
+}
+
+func addHeadersAndCookies(fr *Response, w http.ResponseWriter) {
 	for header, values := range fr.Headers {
 		for _, value := range values {
 			w.Header().Add(header, value)
 		}
-
 	}
+
 	if len(fr.Cookies) > 0 {
 		cookies := []string{}
 		for cookie, value := range fr.Cookies {
 			cookies = append(cookies, fmt.Sprintf("%s=%s", cookie, value))
 		}
 		w.Header().Add("Set-Cookie", strings.Join(cookies, ";"))
 	}
+}
 
-	w.WriteHeader(fr.StatusCode)
-	io.WriteString(w, fr.Body)
+// streamResponse - stream response
+func streamResponse(fr *Response, w http.ResponseWriter, req *http.Request) {
+	addHeadersAndCookies(fr, w)
+
+	for _, response := range gjson.Parse(fr.Body).Array() {
+		time.Sleep(time.Second * 2)
+		select {
+		case <-req.Context().Done():
+			return
+		default:
+			ba, _ := json.Marshal((response.Value()))
+			fmt.Fprintf(w, "data: %s\n\n", string(ba))
+			w.(http.Flusher).Flush()
+		}
+	}
 }

pkg/mock/message_translator.go

@@ -11,7 +11,7 @@ type MockRequestBuilder interface {
 
 // MockResponseWriter defines the translator from config.Response to http.ResponseWriter
 type MockResponseWriter interface {
-	WriteHTTPResponseFromDefinition(fr *Response, w http.ResponseWriter)
+	WriteHTTPResponseFromDefinition(fr *Response, w http.ResponseWriter, req *http.Request)
 }
 
 // MessageTranslator defines the translator contract between http and mock and viceversa.