tests(manager): add tests for server.go, validate workerID in middleware

manager/middleware.go

@@ -1,6 +1,9 @@
 package manager
 
 import (
+	"fmt"
+	"net/http"
+
 	"github.com/gin-gonic/gin"
 )
 
@@ -14,3 +17,17 @@ func contextErrorLogger(c *gin.Context) {
 	// pass on to the next middleware in chain
 	c.Next()
 }
+
+func (s *managerServer) workerIDValidator(c *gin.Context) {
+	workerID := c.Param("id")
+	_, err := s.adapter.GetWorker(workerID)
+	if err != nil {
+		// no worker named `workerID` exists
+		err := fmt.Errorf("invalid workerID %s", workerID)
+		s.returnErrJSON(c, http.StatusBadRequest, err)
+		c.Abort()
+		return
+	}
+	// pass on to the next middleware in chain
+	c.Next()
+}