Basic WebSocket mock in AWS ApiGateway using CloudFormation in AWS

aws-websockets-api-gw-mock.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: |
  AWS CloudFormation template for Mock WebSocket API Gateway. When deploying this stack please remember to check the option:
   - I acknowledge that AWS CloudFormation might create IAM resources.
  This template can help you to solve issues like:
  - CloudWatch Logs role ARN must be set in account settings to enable logging
  - Execution failed due to configuration error: statusCode should be an integer which defined in request template
  - This custom domain name cannot map to WEBSOCKET protocol APIs
  - Error during WebSocket handshake: Unexpected response code: 500

Resources:
  ApiGwAccountConfig:
    Type: "AWS::ApiGateway::Account"
    Properties:
      CloudWatchRoleArn: !GetAtt "ApiGatewayLoggingRole.Arn"
  ApiGatewayLoggingRole:
    Type: "AWS::IAM::Role"
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - "apigateway.amazonaws.com"
            Action: "sts:AssumeRole"
      Path: "/"
      ManagedPolicyArns:
        - !Sub "arn:${AWS::Partition}:iam::aws:policy/service-role/AmazonAPIGatewayPushToCloudWatchLogs"

  WebSocketMock:
    Type: AWS::ApiGatewayV2::Api
    Properties:
      Name: WebSocketMock
      ProtocolType: WEBSOCKET
      RouteSelectionExpression: "$request.body.message"
      Description: "Mock WebSocket API Gateway."
  
  ConnectRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref WebSocketMock
      RouteKey: $connect
      RouteResponseSelectionExpression: '$default'
      AuthorizationType: NONE
      ApiKeyRequired: false
      OperationName: ConnectRoute
      Target: !Join
        - '/'
        - - 'integrations'
          - !Ref ConnectInteg
  
  ConnectInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref WebSocketMock
      Description: Connect Integration
      IntegrationType: MOCK
      RequestTemplates: 
        "200" : '{"statusCode" : 200}'
      TemplateSelectionExpression: '200'
      PassthroughBehavior: 'WHEN_NO_MATCH'
  
  ConnectIntegResp:
    Type: AWS::ApiGatewayV2::IntegrationResponse
    Properties:
      ApiId: !Ref WebSocketMock
      IntegrationId: !Ref ConnectInteg
      IntegrationResponseKey: '$default'
      ResponseTemplates:
        "200" : '{"statusCode" : 200}'
  
  ConnectRouteResponse:
    Type: AWS::ApiGatewayV2::RouteResponse
    Properties:
      RouteId: !Ref ConnectRoute
      ApiId: !Ref WebSocketMock
      RouteResponseKey: $default

  DisconnectRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref WebSocketMock
      RouteKey: $disconnect
      RouteResponseSelectionExpression: '$default'
      AuthorizationType: NONE
      OperationName: DisconnectRoute
      Target: !Join
        - '/'
        - - 'integrations'
          - !Ref DisconnectInteg
  
  DisconnectInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref WebSocketMock
      Description: Disconnect Integration
      IntegrationType: MOCK
      RequestTemplates: 
        "200" : '{"statusCode" : 200}'
      TemplateSelectionExpression: '200'
      PassthroughBehavior: 'WHEN_NO_MATCH'

  DisconnectIntegResp:
    Type: AWS::ApiGatewayV2::IntegrationResponse
    Properties:
      ApiId: !Ref WebSocketMock
      IntegrationId: !Ref DisconnectInteg
      IntegrationResponseKey: '$default'
      ResponseTemplates:
        "200" : '{"statusCode" : 200}'
  
  DisconnectRouteResponse:
    Type: AWS::ApiGatewayV2::RouteResponse
    Properties:
      RouteId: !Ref DisconnectRoute
      ApiId: !Ref WebSocketMock
      RouteResponseKey: $default
  
  DefaultRoute:
    Type: AWS::ApiGatewayV2::Route
    Properties:
      ApiId: !Ref WebSocketMock
      RouteKey: $default
      RouteResponseSelectionExpression: '$default'
      AuthorizationType: NONE
      OperationName: DefaultRoute
      Target: !Join
        - '/'
        - - 'integrations'
          - !Ref DefaultInteg
  
  DefaultInteg:
    Type: AWS::ApiGatewayV2::Integration
    Properties:
      ApiId: !Ref WebSocketMock
      Description: Default Integration
      IntegrationType: MOCK
      RequestTemplates: 
        "200" : '{"statusCode" : 200}'
      TemplateSelectionExpression: '200'

  DefaultIntegResp:
    Type: AWS::ApiGatewayV2::IntegrationResponse
    Properties:
      ApiId: !Ref WebSocketMock
      IntegrationId: !Ref DefaultInteg
      IntegrationResponseKey: $default
      ResponseTemplates: 
        "200" : '{"statusCode" : 200, "connectionId" : "$context.connectionId"}'
      TemplateSelectionExpression: '200'
  
  DefaultRouteResponse:
    Type: AWS::ApiGatewayV2::RouteResponse
    Properties:
      RouteId: !Ref DefaultRoute
      ApiId: !Ref WebSocketMock
      RouteResponseKey: $default

  Deployment:
    Type: AWS::ApiGatewayV2::Deployment
    DependsOn:
    - ConnectRoute
    - DisconnectRoute
    - DefaultRoute
    Properties:
      ApiId: !Ref WebSocketMock

  Stage:
    Type: AWS::ApiGatewayV2::Stage
    Properties:
      StageName: LATEST
      Description: One and only Stage
      DeploymentId: !Ref Deployment
      ApiId: !Ref WebSocketMock
      DefaultRouteSettings:
        DetailedMetricsEnabled: true
        LoggingLevel: INFO