support response as a random image

Author: LinuxSuRen

docs/site/content/zh/latest/tasks/mock.md

@@ -153,6 +153,20 @@ items:
       bodyFromFile: /tmp/baidu.html
 ```
 
+通过下面的方式也可以生成图片：
+
+```yaml
+items:
+- name: image
+    request:
+      path: /v1/image
+    response:
+      header:
+        Content-Type: image/png
+      body: |
+        {{ randImage 300 300 }}
+```
+
 #### 条件判断
 
 对于查询类的 API，通常会接收参数，并根据参数的不同，返回相应的数据。这时候，可以用到条件判断的表达式：

pkg/mock/in_memory.go

@@ -476,6 +476,16 @@ func (h *advanceHandler) handle(w http.ResponseWriter, req *http.Request) {
 		}
 	}
 
+	if strings.HasPrefix(h.item.Response.Header[util.ContentType], "image/") {
+		if strings.HasPrefix(string(h.item.Response.BodyData), util.ImageBase64Prefix) {
+			// decode base64 image data
+			imgData := strings.TrimPrefix(string(h.item.Response.BodyData), util.ImageBase64Prefix)
+			if h.item.Response.BodyData, err = base64.StdEncoding.DecodeString(imgData); err != nil {
+				memLogger.Error(err, "failed to decode base64 image data")
+			}
+		}
+	}
+
 	if err == nil {
 		h.item.Response.Header[util.ContentLength] = fmt.Sprintf("%d", len(h.item.Response.BodyData))
 		w.Header().Set(util.ContentLength, h.item.Response.Header[util.ContentLength])

pkg/mock/testdata/api.yaml

@@ -56,6 +56,14 @@ items:
             "status": "success"
           }]
         }
+  - name: image
+    request:
+      path: /v1/image
+    response:
+      header:
+        Content-Type: image/png
+      body: |
+        {{ randImage 300 300 }}
 proxies:
   - path: /v1/myProjects
     target: http://localhost:{{.GetPort}}