diff --git a/common/models.go b/common/models.go
index 556e0cc..8f603fe 100644
--- a/common/models.go
+++ b/common/models.go
@@ -53,9 +53,9 @@ type SimulationModel struct {
 	// Name of simulation model
 	Name string `json:"name" gorm:"not null"`
 	// Number of output signals
-	OutputLength int `json:"outputLength" gorm:"default:1"`
+	OutputLength int `json:"outputLength" gorm:"default:0"`
 	// Number of input signals
-	InputLength int `json:"inputLength" gorm:"default:1"`
+	InputLength int `json:"inputLength" gorm:"default:0"`
 	// Start parameters of simulation model as JSON
 	StartParameters postgres.Jsonb `json:"startParameters"`
 	// ID of Scenario to which simulation model belongs
diff --git a/common/responses.go b/common/responses.go
index 45b1e70..4de4cc6 100644
--- a/common/responses.go
+++ b/common/responses.go
@@ -2,16 +2,6 @@ package common
 
 import "github.com/jinzhu/gorm/dialects/postgres"
 
-type SimulationModelResponse struct {
-	ID              uint           `json:"id"`
-	Name            string         `json:"name"`
-	OutputLength    int            `json:"outputLength"`
-	InputLength     int            `json:"inputLength"`
-	ScenarioID      uint           `json:"scenarioID"`
-	SimulatorID     uint           `json:"simulatorID"`
-	StartParameters postgres.Jsonb `json:"startParameters"`
-}
-
 type DashboardResponse struct {
 	ID         uint   `json:"id"`
 	Name       string `json:"name"`
@@ -61,14 +51,6 @@ type ResponseMsg struct {
 	Message string `json:"message"`
 }
 
-type ResponseMsgSimulationModels struct {
-	SimulationModels []SimulationModelResponse `json:"models"`
-}
-
-type ResponseMsgSimulationModel struct {
-	SimulationModel SimulationModelResponse `json:"model"`
-}
-
 type ResponseMsgSignals struct {
 	Signals []SignalResponse `json:"signals"`
 }
diff --git a/common/serializers.go b/common/serializers.go
index 90899c4..5d3be7e 100644
--- a/common/serializers.go
+++ b/common/serializers.go
@@ -4,40 +4,6 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-// Model/s Serializers
-
-type SimulationModelsSerializer struct {
-	Ctx              *gin.Context
-	SimulationModels []SimulationModel
-}
-
-func (self *SimulationModelsSerializer) Response() []SimulationModelResponse {
-	response := []SimulationModelResponse{}
-	for _, simulationmodel := range self.SimulationModels {
-		serializer := SimulationModelSerializer{self.Ctx, simulationmodel}
-		response = append(response, serializer.Response())
-	}
-	return response
-}
-
-type SimulationModelSerializer struct {
-	Ctx *gin.Context
-	SimulationModel
-}
-
-func (self *SimulationModelSerializer) Response() SimulationModelResponse {
-	response := SimulationModelResponse{
-		ID:              self.ID,
-		Name:            self.Name,
-		OutputLength:    self.OutputLength,
-		InputLength:     self.InputLength,
-		ScenarioID:      self.ScenarioID,
-		SimulatorID:     self.SimulatorID,
-		StartParameters: self.StartParameters,
-	}
-	return response
-}
-
 // Dashboard/s Serializers
 
 type DashboardsSerializer struct {
diff --git a/common/testdata.go b/common/testdata.go
index 3d8869a..9f8a539 100644
--- a/common/testdata.go
+++ b/common/testdata.go
@@ -84,7 +84,6 @@ var SimulatorB = Simulator{
 
 var startParametersA = json.RawMessage(`{"parameter1" : "testValue1A", "parameter2" : "testValue2A", "parameter3" : 42}`)
 var startParametersB = json.RawMessage(`{"parameter1" : "testValue1B", "parameter2" : "testValue2B", "parameter3" : 43}`)
-var startParametersC = json.RawMessage(`{"parameter1" : "testValue1C", "parameter2" : "testValue2C", "parameter3" : 44}`)
 
 var ScenarioA = Scenario{
 	Name:            "Scenario_A",
@@ -101,72 +100,14 @@ var ScenarioB = Scenario{
 
 var SimulationModelA = SimulationModel{
 	Name:            "SimulationModel_A",
-	OutputLength:    1,
-	InputLength:     1,
 	StartParameters: postgres.Jsonb{startParametersA},
 }
 
-var SimulationModelA_response = SimulationModelResponse{
-	ID:              1,
-	Name:            SimulationModelA.Name,
-	InputLength:     SimulationModelA.InputLength,
-	OutputLength:    SimulationModelA.OutputLength,
-	StartParameters: SimulationModelA.StartParameters,
-}
-
 var SimulationModelB = SimulationModel{
 	Name:            "SimulationModel_B",
-	OutputLength:    1,
-	InputLength:     1,
 	StartParameters: postgres.Jsonb{startParametersB},
 }
 
-var SimulationModelB_response = SimulationModelResponse{
-	ID:              2,
-	Name:            SimulationModelB.Name,
-	InputLength:     SimulationModelB.InputLength,
-	OutputLength:    SimulationModelB.OutputLength,
-	StartParameters: SimulationModelB.StartParameters,
-}
-
-var SimulationModelC = SimulationModel{
-	Name:            "SimulationModel_C",
-	OutputLength:    1,
-	InputLength:     1,
-	StartParameters: postgres.Jsonb{startParametersC},
-}
-
-var SimulationModelC_response = SimulationModelResponse{
-	ID:              3,
-	Name:            SimulationModelC.Name,
-	InputLength:     SimulationModelC.InputLength,
-	OutputLength:    SimulationModelC.OutputLength,
-	ScenarioID:      SimulationModelC.ScenarioID,
-	SimulatorID:     SimulationModelC.SimulatorID,
-	StartParameters: SimulationModelC.StartParameters,
-}
-
-var SimulationModelCUpdated = SimulationModel{
-	Name:            "SimulationModel_CUpdated",
-	OutputLength:    SimulationModelC.OutputLength,
-	InputLength:     SimulationModelC.InputLength,
-	ScenarioID:      SimulationModelC.ScenarioID,
-	SimulatorID:     2,
-	StartParameters: SimulationModelC.StartParameters,
-	InputMapping:    SimulationModelC.InputMapping,
-	OutputMapping:   SimulationModelC.OutputMapping,
-}
-
-var SimulationModelCUpdated_response = SimulationModelResponse{
-	ID:              3,
-	Name:            SimulationModelCUpdated.Name,
-	InputLength:     SimulationModelCUpdated.InputLength,
-	OutputLength:    SimulationModelCUpdated.OutputLength,
-	ScenarioID:      SimulationModelCUpdated.ScenarioID,
-	SimulatorID:     SimulationModelCUpdated.SimulatorID,
-	StartParameters: SimulationModelCUpdated.StartParameters,
-}
-
 // Signals
 
 var OutSignalA = Signal{
diff --git a/common/utilities.go b/common/utilities.go
index c27bbea..70fb75d 100644
--- a/common/utilities.go
+++ b/common/utilities.go
@@ -152,8 +152,9 @@ func CompareResponse(resp *bytes.Buffer, expected interface{}) error {
 	}
 	// Compare
 	opts := jsondiff.DefaultConsoleOptions()
-	diff, _ := jsondiff.Compare(resp.Bytes(), expectedBytes, &opts)
+	diff, text := jsondiff.Compare(resp.Bytes(), expectedBytes, &opts)
 	if diff.String() != "FullMatch" && diff.String() != "SupersetMatch" {
+		fmt.Println(text)
 		return fmt.Errorf("Response: Expected \"%v\". Got \"%v\".",
 			"(FullMatch OR SupersetMatch)", diff.String())
 	}
diff --git a/routes/simulationmodel/simulationmodel_endpoints.go b/routes/simulationmodel/simulationmodel_endpoints.go
index 2bb5565..8f11c8a 100644
--- a/routes/simulationmodel/simulationmodel_endpoints.go
+++ b/routes/simulationmodel/simulationmodel_endpoints.go
@@ -1,6 +1,7 @@
 package simulationmodel
 
 import (
+	"fmt"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -22,11 +23,10 @@ func RegisterSimulationModelEndpoints(r *gin.RouterGroup) {
 // @ID getSimulationModels
 // @Produce  json
 // @Tags models
-// @Success 200 {array} common.SimulationModelResponse "Array of models to which belong to scenario"
-// @Failure 401 "Unauthorized Access"
-// @Failure 403 "Access forbidden."
-// @Failure 404 "Not found"
-// @Failure 500 "Internal server error"
+// @Success 200 {object} docs.ResponseSimulationModels "Simulation models which belong to scenario"
+// @Failure 404 {object} docs.ResponseError "Not found"
+// @Failure 422 {object} docs.ResponseError "Unprocessable entity"
+// @Failure 500 {object} docs.ResponseError "Internal server error"
 // @Param scenarioID query int true "Scenario ID"
 // @Router /models [get]
 func getSimulationModels(c *gin.Context) {
@@ -43,9 +43,8 @@ func getSimulationModels(c *gin.Context) {
 		return
 	}
 
-	serializer := common.SimulationModelsSerializer{c, models}
 	c.JSON(http.StatusOK, gin.H{
-		"models": serializer.Response(),
+		"models": models,
 	})
 }
 
@@ -55,45 +54,54 @@ func getSimulationModels(c *gin.Context) {
 // @Accept json
 // @Produce json
 // @Tags models
-// @Param inputSimulationModel body common.ResponseMsgSimulationModel true "Simulation model to be added incl. IDs of scenario and simulator"
-// @Success 200 "OK."
-// @Failure 401 "Unauthorized Access"
-// @Failure 403 "Access forbidden."
-// @Failure 404 "Not found"
-// @Failure 500 "Internal server error"
+// @Param inputSimulationModel body simulationmodel.validNewSimulationModel true "Simulation model to be added incl. IDs of scenario and simulator"
+// @Success 200 {object} docs.ResponseSimulationModel "simulation model that was added"
+// @Failure 400 {object} docs.ResponseError "Bad request"
+// @Failure 404 {object} docs.ResponseError "Not found"
+// @Failure 422 {object} docs.ResponseError "Unprocessable entity"
+// @Failure 500 {object} docs.ResponseError "Internal server error"
 // @Router /models [post]
 func addSimulationModel(c *gin.Context) {
 
-	var newModelData common.ResponseMsgSimulationModel
-	err := c.BindJSON(&newModelData)
+	// Bind the request to JSON
+	var req addSimulationModelRequest
+	err := c.ShouldBindJSON(&req)
 	if err != nil {
-		errormsg := "Bad request. Error binding form data to JSON: " + err.Error()
 		c.JSON(http.StatusBadRequest, gin.H{
-			"error": errormsg,
+			"success": false,
+			"message": "Bad request. Error binding form data to JSON: " + err.Error(),
 		})
 		return
 	}
 
-	var newModel SimulationModel
-	newModel.ID = newModelData.SimulationModel.ID
-	newModel.Name = newModelData.SimulationModel.Name
-	newModel.SimulatorID = newModelData.SimulationModel.SimulatorID
-	newModel.ScenarioID = newModelData.SimulationModel.ScenarioID
-	newModel.StartParameters = newModelData.SimulationModel.StartParameters
-	newModel.OutputLength = 0
-	newModel.InputLength = 0
+	// validate the request
+	if err = req.validate(); err != nil {
+		c.JSON(http.StatusUnprocessableEntity, gin.H{
+			"success": false,
+			"message": fmt.Sprintf("%v", err),
+		})
+		return
+	}
 
-	ok, _ := scenario.CheckPermissions(c, common.Create, "body", int(newModel.ScenarioID))
+	// Create the new simulation model from the request
+	newSimulationModel := req.createSimulationModel()
+
+	// check access to the scenario
+	ok, _ := scenario.CheckPermissions(c, common.Create, "body", int(newSimulationModel.ScenarioID))
 	if !ok {
 		return
 	}
 
-	err = newModel.addToScenario()
-	if common.ProvideErrorResponse(c, err) == false {
-		c.JSON(http.StatusOK, gin.H{
-			"message": "OK.",
-		})
+	// add the new simulation model to the scenario
+	err = newSimulationModel.addToScenario()
+	if err != nil {
+		common.ProvideErrorResponse(c, err)
+		return
 	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"model": newSimulationModel.SimulationModel,
+	})
 }
 
 // updateSimulationModel godoc
@@ -102,37 +110,61 @@ func addSimulationModel(c *gin.Context) {
 // @Tags models
 // @Accept json
 // @Produce json
-// @Param inputSimulationModel body common.ResponseMsgSimulationModel true "Simulation model to be updated"
-// @Success 200 "OK."
-// @Failure 401 "Unauthorized Access"
-// @Failure 403 "Access forbidden."
-// @Failure 404 "Not found"
-// @Failure 500 "Internal server error"
+// @Param inputSimulationModel body simulationmodel.validUpdatedSimulationModel true "Simulation model to be updated"
+// @Success 200 {object} docs.ResponseSimulationModel "simulation model that was added"
+// @Failure 400 {object} docs.ResponseError "Bad request"
+// @Failure 404 {object} docs.ResponseError "Not found"
+// @Failure 422 {object} docs.ResponseError "Unprocessable entity"
+// @Failure 500 {object} docs.ResponseError "Internal server error"
 // @Param modelID path int true "Model ID"
 // @Router /models/{modelID} [put]
 func updateSimulationModel(c *gin.Context) {
 
-	ok, m := CheckPermissions(c, common.Update, "path", -1)
+	ok, oldSimulationModel := CheckPermissions(c, common.Update, "path", -1)
 	if !ok {
 		return
 	}
 
-	var modifiedModel common.ResponseMsgSimulationModel
-	err := c.BindJSON(&modifiedModel)
+	var req updateSimulationModelRequest
+	err := c.BindJSON(&req)
 	if err != nil {
-		errormsg := "Bad request. Error binding form data to JSON: " + err.Error()
 		c.JSON(http.StatusBadRequest, gin.H{
-			"error": errormsg,
+			"success": false,
+			"message": "Bad request. Error binding form data to JSON: " + err.Error(),
 		})
 		return
 	}
 
-	err = m.Update(modifiedModel.SimulationModel)
-	if common.ProvideErrorResponse(c, err) == false {
-		c.JSON(http.StatusOK, gin.H{
-			"message": "OK.",
+	// Validate the request
+	if err := req.validate(); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"success": false,
+			"message": fmt.Sprintf("%v", err),
 		})
+		return
 	}
+
+	// Create the updatedSimulationModel from oldSimulationModel
+	updatedSimulationModel, err := req.updatedSimulationModel(oldSimulationModel)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"success": false,
+			"message": fmt.Sprintf("%v", err),
+		})
+		return
+	}
+
+	// Finally, update the simulation model
+	err = oldSimulationModel.Update(updatedSimulationModel)
+	if err != nil {
+		common.ProvideErrorResponse(c, err)
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"model": updatedSimulationModel.SimulationModel,
+	})
+
 }
 
 // getSimulationModel godoc
@@ -140,11 +172,11 @@ func updateSimulationModel(c *gin.Context) {
 // @ID getSimulationModel
 // @Tags models
 // @Produce json
-// @Success 200 {object} common.SimulationModelResponse "Requested simulation model."
-// @Failure 401 "Unauthorized Access"
-// @Failure 403 "Access forbidden."
-// @Failure 404 "Not found"
-// @Failure 500 "Internal server error"
+// @Success 200 {object} docs.ResponseSimulationModel "simulation model that was requested"
+// @Failure 400 {object} docs.ResponseError "Bad request"
+// @Failure 404 {object} docs.ResponseError "Not found"
+// @Failure 422 {object} docs.ResponseError "Unprocessable entity"
+// @Failure 500 {object} docs.ResponseError "Internal server error"
 // @Param modelID path int true "Model ID"
 // @Router /models/{modelID} [get]
 func getSimulationModel(c *gin.Context) {
@@ -154,9 +186,8 @@ func getSimulationModel(c *gin.Context) {
 		return
 	}
 
-	serializer := common.SimulationModelSerializer{c, m.SimulationModel}
 	c.JSON(http.StatusOK, gin.H{
-		"model": serializer.Response(),
+		"model": m.SimulationModel,
 	})
 }
 
@@ -165,11 +196,11 @@ func getSimulationModel(c *gin.Context) {
 // @ID deleteSimulationModel
 // @Tags models
 // @Produce json
-// @Success 200 "OK."
-// @Failure 401 "Unauthorized Access"
-// @Failure 403 "Access forbidden."
-// @Failure 404 "Not found"
-// @Failure 500 "Internal server error"
+// @Success 200 {object} docs.ResponseSimulationModel "simulation model that was deleted"
+// @Failure 400 {object} docs.ResponseError "Bad request"
+// @Failure 404 {object} docs.ResponseError "Not found"
+// @Failure 422 {object} docs.ResponseError "Unprocessable entity"
+// @Failure 500 {object} docs.ResponseError "Internal server error"
 // @Param modelID path int true "Model ID"
 // @Router /models/{modelID} [delete]
 func deleteSimulationModel(c *gin.Context) {
@@ -185,6 +216,6 @@ func deleteSimulationModel(c *gin.Context) {
 	}
 
 	c.JSON(http.StatusOK, gin.H{
-		"message": "OK.",
+		"model": m.SimulationModel,
 	})
 }
diff --git a/routes/simulationmodel/simulationmodel_methods.go b/routes/simulationmodel/simulationmodel_methods.go
index 295376b..37dfe54 100644
--- a/routes/simulationmodel/simulationmodel_methods.go
+++ b/routes/simulationmodel/simulationmodel_methods.go
@@ -1,8 +1,6 @@
 package simulationmodel
 
 import (
-	"fmt"
-
 	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/common"
 	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/routes/scenario"
 	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/routes/simulator"
@@ -22,7 +20,7 @@ func (m *SimulationModel) ByID(id uint) error {
 	db := common.GetDB()
 	err := db.Find(m, id).Error
 	if err != nil {
-		return fmt.Errorf("Simulation Model with id=%v does not exist", id)
+		return err
 	}
 	return nil
 }
@@ -55,7 +53,7 @@ func (m *SimulationModel) addToScenario() error {
 	return err
 }
 
-func (m *SimulationModel) Update(modifiedSimulationModel common.SimulationModelResponse) error {
+func (m *SimulationModel) Update(modifiedSimulationModel SimulationModel) error {
 	db := common.GetDB()
 
 	if m.SimulatorID != modifiedSimulationModel.SimulatorID {
@@ -82,12 +80,15 @@ func (m *SimulationModel) Update(modifiedSimulationModel common.SimulationModelR
 		}
 	}
 
+	if m.ScenarioID != modifiedSimulationModel.ScenarioID {
+		// TODO do we allow this case?
+	}
+
 	err := db.Model(m).Updates(map[string]interface{}{
 		"Name":            modifiedSimulationModel.Name,
-		"OutputLength":    modifiedSimulationModel.OutputLength,
-		"InputLength":     modifiedSimulationModel.InputLength,
 		"StartParameters": modifiedSimulationModel.StartParameters,
 		"SimulatorID":     modifiedSimulationModel.SimulatorID,
+		//"ScenarioID":     modifiedSimulationModel.ScenarioID,
 	}).Error
 
 	return err
diff --git a/routes/simulationmodel/simulationmodel_middleware.go b/routes/simulationmodel/simulationmodel_middleware.go
index ee18883..f54ab49 100644
--- a/routes/simulationmodel/simulationmodel_middleware.go
+++ b/routes/simulationmodel/simulationmodel_middleware.go
@@ -17,7 +17,10 @@ func CheckPermissions(c *gin.Context, operation common.CRUD, modelIDSource strin
 
 	err := common.ValidateRole(c, common.ModelSimulationModel, operation)
 	if err != nil {
-		c.JSON(http.StatusUnprocessableEntity, "Access denied (role validation failed).")
+		c.JSON(http.StatusUnprocessableEntity, gin.H{
+			"success": false,
+			"message": fmt.Sprintf("Access denied (role validation failed): %v", err),
+		})
 		return false, m
 	}
 
@@ -27,16 +30,17 @@ func CheckPermissions(c *gin.Context, operation common.CRUD, modelIDSource strin
 		if err != nil {
 			errormsg := fmt.Sprintf("Bad request. No or incorrect format of modelID path parameter")
 			c.JSON(http.StatusBadRequest, gin.H{
-				"error": errormsg,
+				"success": false,
+				"message": errormsg,
 			})
 			return false, m
 		}
 	} else if modelIDSource == "query" {
 		modelID, err = strconv.Atoi(c.Request.URL.Query().Get("modelID"))
 		if err != nil {
-			errormsg := fmt.Sprintf("Bad request. No or incorrect format of modelID query parameter")
 			c.JSON(http.StatusBadRequest, gin.H{
-				"error": errormsg,
+				"success": false,
+				"message": fmt.Sprintf("Bad request. No or incorrect format of modelID query parameter"),
 			})
 			return false, m
 		}
diff --git a/routes/simulationmodel/simulationmodel_test.go b/routes/simulationmodel/simulationmodel_test.go
index 9dc8c11..975138f 100644
--- a/routes/simulationmodel/simulationmodel_test.go
+++ b/routes/simulationmodel/simulationmodel_test.go
@@ -1,65 +1,364 @@
 package simulationmodel
 
 import (
-	"encoding/json"
-	"testing"
-
-	"github.com/gin-gonic/gin"
-
+	"fmt"
 	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/common"
+	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/routes/scenario"
+	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/routes/simulator"
 	"git.rwth-aachen.de/acs/public/villas/villasweb-backend-go/routes/user"
+	"github.com/gin-gonic/gin"
+	"github.com/jinzhu/gorm"
+	"github.com/jinzhu/gorm/dialects/postgres"
+	"github.com/stretchr/testify/assert"
+	"os"
+	"testing"
 )
 
-// Test /models endpoints
-func TestSimulationModelEndpoints(t *testing.T) {
+var router *gin.Engine
+var db *gorm.DB
 
-	var token string
+type SimulationModelRequest struct {
+	Name            string         `json:"name,omitempty"`
+	ScenarioID      uint           `json:"scenarioID,omitempty"`
+	SimulatorID     uint           `json:"simulatorID,omitempty"`
+	StartParameters postgres.Jsonb `json:"startParameters,omitempty"`
+}
 
-	var myModels = []common.SimulationModelResponse{common.SimulationModelA_response, common.SimulationModelB_response}
-	var msgModels = common.ResponseMsgSimulationModels{SimulationModels: myModels}
-	var msgModel = common.ResponseMsgSimulationModel{SimulationModel: common.SimulationModelC_response}
-	var msgModelupdated = common.ResponseMsgSimulationModel{SimulationModel: common.SimulationModelCUpdated_response}
+type SimulatorRequest struct {
+	UUID       string         `json:"uuid,omitempty"`
+	Host       string         `json:"host,omitempty"`
+	Modeltype  string         `json:"modelType,omitempty"`
+	State      string         `json:"state,omitempty"`
+	Properties postgres.Jsonb `json:"properties,omitempty"`
+}
 
-	db := common.DummyInitDB()
+type ScenarioRequest struct {
+	Name            string         `json:"name,omitempty"`
+	Running         bool           `json:"running,omitempty"`
+	StartParameters postgres.Jsonb `json:"startParameters,omitempty"`
+}
+
+func addScenarioAndSimulator() (scenarioID uint, simulatorID uint) {
+
+	// authenticate as admin
+	token, _ := common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.AdminCredentials)
+
+	// POST $newSimulatorA
+	newSimulatorA := SimulatorRequest{
+		UUID:       common.SimulatorA.UUID,
+		Host:       common.SimulatorA.Host,
+		Modeltype:  common.SimulatorA.Modeltype,
+		State:      common.SimulatorA.State,
+		Properties: common.SimulatorA.Properties,
+	}
+	_, resp, _ := common.NewTestEndpoint(router, token,
+		"/api/simulators", "POST", common.KeyModels{"simulator": newSimulatorA})
+
+	// Read newSimulator's ID from the response
+	newSimulatorID, _ := common.GetResponseID(resp)
+
+	// authenticate as normal user
+	token, _ = common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.UserACredentials)
+
+	// POST $newScenario
+	newScenario := ScenarioRequest{
+		Name:            common.ScenarioA.Name,
+		Running:         common.ScenarioA.Running,
+		StartParameters: common.ScenarioA.StartParameters,
+	}
+	_, resp, _ = common.NewTestEndpoint(router, token,
+		"/api/scenarios", "POST", common.KeyModels{"scenario": newScenario})
+
+	// Read newScenario's ID from the response
+	newScenarioID, _ := common.GetResponseID(resp)
+
+	return uint(newScenarioID), uint(newSimulatorID)
+}
+
+func TestMain(m *testing.M) {
+
+	db = common.DummyInitDB()
 	defer db.Close()
-	common.DummyPopulateDB(db)
 
-	router := gin.Default()
+	router = gin.Default()
 	api := router.Group("/api")
 
-	// All endpoints require authentication except when someone wants to
-	// login (POST /authenticate)
 	user.RegisterAuthenticate(api.Group("/authenticate"))
-
 	api.Use(user.Authentication(true))
-
 	RegisterSimulationModelEndpoints(api.Group("/models"))
+	// scenario endpoints required here to first add a scenario to the DB
+	// that can be associated with a new simulation model
+	scenario.RegisterScenarioEndpoints(api.Group("/scenarios"))
+	// simulator endpoints required here to first add a simulator to the DB
+	// that can be associated with a new simulation model
+	simulator.RegisterSimulatorEndpoints(api.Group("/simulators"))
 
-	credjson, _ := json.Marshal(common.CredUser)
-	msgOKjson, _ := json.Marshal(common.MsgOK)
-	msgModelsjson, _ := json.Marshal(msgModels)
-	msgModeljson, _ := json.Marshal(msgModel)
-	msgModelupdatedjson, _ := json.Marshal(msgModelupdated)
+	os.Exit(m.Run())
+}
 
-	token = common.AuthenticateForTest(t, router, "/api/authenticate", "POST", credjson, 200)
+func TestAddSimulationModel(t *testing.T) {
+	common.DropTables(db)
+	common.MigrateModels(db)
+	common.DummyAddOnlyUserTableWithAdminAndUsersDB(db)
 
-	// test GET models
-	common.TestEndpoint(t, router, token, "/api/models?scenarioID=1", "GET", nil, 200, msgModelsjson)
+	// prepare the content of the DB for testing
+	// by adding a scenario and a simulator to the DB
+	// using the respective endpoints of the API
+	scenarioID, simulatorID := addScenarioAndSimulator()
 
-	// test POST models
-	common.TestEndpoint(t, router, token, "/api/models", "POST", msgModeljson, 200, msgOKjson)
+	// authenticate as normal user
+	token, err := common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.UserACredentials)
+	assert.NoError(t, err)
 
-	// test GET models/:ModelID to check if previous POST worked correctly
-	common.TestEndpoint(t, router, token, "/api/models/3", "GET", nil, 200, msgModeljson)
+	// test POST models/ $newSimulationModel
+	newSimulationModel := SimulationModelRequest{
+		Name:            common.SimulationModelA.Name,
+		ScenarioID:      scenarioID,
+		SimulatorID:     simulatorID,
+		StartParameters: common.SimulationModelA.StartParameters,
+	}
+	code, resp, err := common.NewTestEndpoint(router, token,
+		"/api/models", "POST", common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
 
-	// test PUT models/:ModelID
-	common.TestEndpoint(t, router, token, "/api/models/3", "PUT", msgModelupdatedjson, 200, msgOKjson)
-	common.TestEndpoint(t, router, token, "/api/models/3", "GET", nil, 200, msgModelupdatedjson)
+	// Compare POST's response with the newSimulationModel
+	err = common.CompareResponse(resp, common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
 
-	// test DELETE models/:ModelID
-	common.TestEndpoint(t, router, token, "/api/models/3", "DELETE", nil, 200, msgOKjson)
-	common.TestEndpoint(t, router, token, "/api/models?scenarioID=1", "GET", nil, 200, msgModelsjson)
+	// Read newSimulationModel's ID from the response
+	newSimulationModelID, err := common.GetResponseID(resp)
+	assert.NoError(t, err)
 
-	// TODO add testing for other return codes
+	// Get the newSimulationModel
+	code, resp, err = common.NewTestEndpoint(router, token,
+		fmt.Sprintf("/api/models/%v", newSimulationModelID), "GET", nil)
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Compare GET's response with the newSimulationModel
+	err = common.CompareResponse(resp, common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+
+	// try to POST a malformed simulation model
+	// Required fields are missing
+	malformedNewSimulationModel := SimulationModelRequest{
+		Name: "ThisIsAMalformedRequest",
+	}
+	// this should NOT work and return a unprocessable entity 442 status code
+	code, resp, err = common.NewTestEndpoint(router, token,
+		"/api/models", "POST", common.KeyModels{"model": malformedNewSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 422, code, "Response body: \n%v\n", resp)
 
 }
+
+func TestUpdateSimulationModel(t *testing.T) {
+
+	common.DropTables(db)
+	common.MigrateModels(db)
+	common.DummyAddOnlyUserTableWithAdminAndUsersDB(db)
+
+	// prepare the content of the DB for testing
+	// by adding a scenario and a simulator to the DB
+	// using the respective endpoints of the API
+	scenarioID, simulatorID := addScenarioAndSimulator()
+
+	// authenticate as normal user
+	token, err := common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.UserACredentials)
+	assert.NoError(t, err)
+
+	// test POST models/ $newSimulationModel
+	newSimulationModel := SimulationModelRequest{
+		Name:            common.SimulationModelA.Name,
+		ScenarioID:      scenarioID,
+		SimulatorID:     simulatorID,
+		StartParameters: common.SimulationModelA.StartParameters,
+	}
+	code, resp, err := common.NewTestEndpoint(router, token,
+		"/api/models", "POST", common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Read newSimulationModel's ID from the response
+	newSimulationModelID, err := common.GetResponseID(resp)
+	assert.NoError(t, err)
+
+	updatedSimulationModel := SimulationModelRequest{
+		Name:            common.SimulationModelB.Name,
+		StartParameters: common.SimulationModelB.StartParameters,
+	}
+
+	code, resp, err = common.NewTestEndpoint(router, token,
+		fmt.Sprintf("/api/models/%v", newSimulationModelID), "PUT", common.KeyModels{"model": updatedSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Compare PUT's response with the updatedSimulationModel
+	err = common.CompareResponse(resp, common.KeyModels{"model": updatedSimulationModel})
+	assert.NoError(t, err)
+
+	// Get the updatedSimulationModel
+	code, resp, err = common.NewTestEndpoint(router, token,
+		fmt.Sprintf("/api/models/%v", newSimulationModelID), "GET", nil)
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Compare GET's response with the updatedSimulationModel
+	err = common.CompareResponse(resp, common.KeyModels{"model": updatedSimulationModel})
+	assert.NoError(t, err)
+
+	// try to update a simulation model that does not exist (should return not found 404 status code)
+	code, resp, err = common.NewTestEndpoint(router, token,
+		fmt.Sprintf("/api/models/%v", newSimulationModelID+1), "PUT", common.KeyModels{"scenario": updatedSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 404, code, "Response body: \n%v\n", resp)
+}
+
+func TestDeleteSimulationModel(t *testing.T) {
+	common.DropTables(db)
+	common.MigrateModels(db)
+	common.DummyAddOnlyUserTableWithAdminAndUsersDB(db)
+
+	// prepare the content of the DB for testing
+	// by adding a scenario and a simulator to the DB
+	// using the respective endpoints of the API
+	scenarioID, simulatorID := addScenarioAndSimulator()
+
+	// authenticate as normal user
+	token, err := common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.UserACredentials)
+	assert.NoError(t, err)
+
+	// test POST models/ $newSimulationModel
+	newSimulationModel := SimulationModelRequest{
+		Name:            common.SimulationModelA.Name,
+		ScenarioID:      scenarioID,
+		SimulatorID:     simulatorID,
+		StartParameters: common.SimulationModelA.StartParameters,
+	}
+	code, resp, err := common.NewTestEndpoint(router, token,
+		"/api/models", "POST", common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Read newSimulationModel's ID from the response
+	newSimulationModelID, err := common.GetResponseID(resp)
+	assert.NoError(t, err)
+
+	// Count the number of all the simulation models returned for scenario
+	initialNumber, err := common.LengthOfResponse(router, token,
+		fmt.Sprintf("/api/models?scenarioID=%v", scenarioID), "GET", nil)
+	assert.NoError(t, err)
+
+	// Delete the added newSimulationModel
+	code, resp, err = common.NewTestEndpoint(router, token,
+		fmt.Sprintf("/api/models/%v", newSimulationModelID), "DELETE", nil)
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Compare DELETE's response with the newSimulationModel
+	err = common.CompareResponse(resp, common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+
+	// Again count the number of all the simulation models returned
+	finalNumber, err := common.LengthOfResponse(router, token,
+		fmt.Sprintf("/api/models?scenarioID=%v", scenarioID), "GET", nil)
+	assert.NoError(t, err)
+
+	assert.Equal(t, initialNumber-1, finalNumber)
+}
+
+func TestGetAllSimulationModelsOfScenario(t *testing.T) {
+	common.DropTables(db)
+	common.MigrateModels(db)
+	common.DummyAddOnlyUserTableWithAdminAndUsersDB(db)
+
+	// prepare the content of the DB for testing
+	// by adding a scenario and a simulator to the DB
+	// using the respective endpoints of the API
+	scenarioID, simulatorID := addScenarioAndSimulator()
+
+	// authenticate as normal user
+	token, err := common.NewAuthenticateForTest(router,
+		"/api/authenticate", "POST", common.UserACredentials)
+	assert.NoError(t, err)
+
+	// test POST models/ $newSimulationModel
+	newSimulationModel := SimulationModelRequest{
+		Name:            common.SimulationModelA.Name,
+		ScenarioID:      scenarioID,
+		SimulatorID:     simulatorID,
+		StartParameters: common.SimulationModelA.StartParameters,
+	}
+	code, resp, err := common.NewTestEndpoint(router, token,
+		"/api/models", "POST", common.KeyModels{"model": newSimulationModel})
+	assert.NoError(t, err)
+	assert.Equalf(t, 200, code, "Response body: \n%v\n", resp)
+
+	// Count the number of all the simulation models returned for scenario
+	NumberOfSimulationModels, err := common.LengthOfResponse(router, token,
+		fmt.Sprintf("/api/models?scenarioID=%v", scenarioID), "GET", nil)
+	assert.NoError(t, err)
+
+	assert.Equal(t, 1, NumberOfSimulationModels)
+
+}
+
+//// Test /models endpoints
+//func TestSimulationModelEndpoints(t *testing.T) {
+//
+//	var token string
+//
+//	var myModels = []common.SimulationModelResponse{common.SimulationModelA_response, common.SimulationModelB_response}
+//	var msgModels = common.ResponseMsgSimulationModels{SimulationModels: myModels}
+//	var msgModel = common.ResponseMsgSimulationModel{SimulationModel: common.SimulationModelC_response}
+//	var msgModelupdated = common.ResponseMsgSimulationModel{SimulationModel: common.SimulationModelCUpdated_response}
+//
+//	db := common.DummyInitDB()
+//	defer db.Close()
+//	common.DummyPopulateDB(db)
+//
+//	router := gin.Default()
+//	api := router.Group("/api")
+//
+//	// All endpoints require authentication except when someone wants to
+//	// login (POST /authenticate)
+//	user.RegisterAuthenticate(api.Group("/authenticate"))
+//
+//	api.Use(user.Authentication(true))
+//
+//	RegisterSimulationModelEndpoints(api.Group("/models"))
+//
+//	credjson, _ := json.Marshal(common.CredUser)
+//	msgOKjson, _ := json.Marshal(common.MsgOK)
+//	msgModelsjson, _ := json.Marshal(msgModels)
+//	msgModeljson, _ := json.Marshal(msgModel)
+//	msgModelupdatedjson, _ := json.Marshal(msgModelupdated)
+//
+//	token = common.AuthenticateForTest(t, router, "/api/authenticate", "POST", credjson, 200)
+//
+//	// test GET models
+//	common.TestEndpoint(t, router, token, "/api/models?scenarioID=1", "GET", nil, 200, msgModelsjson)
+//
+//	// test POST models
+//	common.TestEndpoint(t, router, token, "/api/models", "POST", msgModeljson, 200, msgOKjson)
+//
+//	// test GET models/:ModelID to check if previous POST worked correctly
+//	common.TestEndpoint(t, router, token, "/api/models/3", "GET", nil, 200, msgModeljson)
+//
+//	// test PUT models/:ModelID
+//	common.TestEndpoint(t, router, token, "/api/models/3", "PUT", msgModelupdatedjson, 200, msgOKjson)
+//	common.TestEndpoint(t, router, token, "/api/models/3", "GET", nil, 200, msgModelupdatedjson)
+//
+//	// test DELETE models/:ModelID
+//	common.TestEndpoint(t, router, token, "/api/models/3", "DELETE", nil, 200, msgOKjson)
+//	common.TestEndpoint(t, router, token, "/api/models?scenarioID=1", "GET", nil, 200, msgModelsjson)
+//
+//	// TODO add testing for other return codes
+//
+//}
diff --git a/routes/simulationmodel/simulationmodel_validators.go b/routes/simulationmodel/simulationmodel_validators.go
new file mode 100644
index 0000000..c800ccd
--- /dev/null
+++ b/routes/simulationmodel/simulationmodel_validators.go
@@ -0,0 +1,80 @@
+package simulationmodel
+
+import (
+	"encoding/json"
+	"github.com/jinzhu/gorm/dialects/postgres"
+	"github.com/nsf/jsondiff"
+	"gopkg.in/go-playground/validator.v9"
+)
+
+var validate *validator.Validate
+
+type validNewSimulationModel struct {
+	Name            string         `form:"Name" validate:"required"`
+	ScenarioID      uint           `form:"ScenarioID" validate:"required"`
+	SimulatorID     uint           `form:"SimulatorID" validate:"required"`
+	StartParameters postgres.Jsonb `form:"StartParameters" validate:"required"`
+}
+
+type validUpdatedSimulationModel struct {
+	Name            string         `form:"Name" validate:"omitempty"`
+	SimulatorID     uint           `form:"SimulatorID" validate:"omitempty"`
+	StartParameters postgres.Jsonb `form:"StartParameters" validate:"omitempty"`
+}
+
+type addSimulationModelRequest struct {
+	validNewSimulationModel `json:"model"`
+}
+
+type updateSimulationModelRequest struct {
+	validUpdatedSimulationModel `json:"model"`
+}
+
+func (r *addSimulationModelRequest) validate() error {
+	validate = validator.New()
+	errs := validate.Struct(r)
+	return errs
+}
+
+func (r *validUpdatedSimulationModel) validate() error {
+	validate = validator.New()
+	errs := validate.Struct(r)
+	return errs
+}
+
+func (r *addSimulationModelRequest) createSimulationModel() SimulationModel {
+	var s SimulationModel
+
+	s.Name = r.Name
+	s.ScenarioID = r.ScenarioID
+	s.SimulatorID = r.SimulatorID
+	s.StartParameters = r.StartParameters
+
+	return s
+}
+
+func (r *updateSimulationModelRequest) updatedSimulationModel(oldSimulationModel SimulationModel) (SimulationModel, error) {
+	// Use the old SimulationModel as a basis for the updated Simulation model
+	s := oldSimulationModel
+
+	if r.Name != "" {
+		s.Name = r.Name
+	}
+
+	if r.SimulatorID != 0 {
+		s.SimulatorID = r.SimulatorID
+	}
+
+	// only update Params if not empty
+	var emptyJson postgres.Jsonb
+	// Serialize empty json and params
+	emptyJson_ser, _ := json.Marshal(emptyJson)
+	startParams_ser, _ := json.Marshal(r.StartParameters)
+	opts := jsondiff.DefaultConsoleOptions()
+	diff, _ := jsondiff.Compare(emptyJson_ser, startParams_ser, &opts)
+	if diff.String() != "FullMatch" {
+		s.StartParameters = r.StartParameters
+	}
+
+	return s, nil
+}