Vehicle Service Booking System — Pre-Interview Task

Overview

You have been provided with a solution scaffold for a vehicle service booking system. The folder structure, project references, and database connection have been pre-configured for you.

Your task is to implement the business logic, data access, API endpoints, and tests across the existing layers.

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What Has Been Provided

• Project structure across three layers
• DbContext with connection string
• Program.cs with DI registration and middleware
• ~Module.cs files to register DI on individual layers

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Your Task

1. Data Layer

Implement the following models with their requirements as listed below:

Service Type

• Id — Unique id for the type
• Name — Name of the type
• Description — Description of the type
• Duration — Duration in minutes

Appointment

• Id — Unique id for the appointment
• Customer Name — Name of the customer
• Email — Email contact for the customer
• Phone — Phone contact for the customer
• Vehicle VIN — VIN of the vehicle for service
• Service Type ID — Relational Id for the service type of the booking
• Scheduled Date - Date Time of the booking

Implement the repository or repositories:

ServiceTypeRepository

• GetAllAsync() — return all service types
• GetByIdAsync(id) — return a single service type, or null if not found

AppointmentRepository

• GetAllAsync(page, pageSize) — return a paginated list of appointments, including the related ServiceType
• GetByIdAsync(id) — return a single appointment including its related ServiceType, or null if not found
• IsSlotTakenAsync(serviceTypeId, scheduledDateTime) — check if an active appointment already exists for this service type at the given date and time
• CreateAsync(appointment) — create and return the new appointment
• UpdateAsync(appointment) — update and return the appointment
• DeleteAsync(id) — remove the appointment if found

or

Generic Repository

• GetAllAsync(page, pageSize, includes, predicate?) — return a paginated list of entities and relational data from the table, predicate optional
• GetAsync(predicate, includes) — retrieve singular entity and relational data from table
• AnyAsync(predicate) — check to see if entity exists using predicate
• AddAsync(predicate) — insert entity into table
• UpdateAsync(entity) — update entity in table
• DeleteAsync(entity) — delete entity from table

Once your models and repositories are implemented, run your initial migration:

dotnet ef migrations add InitialCreate --project ./VehicleServiceBooking.Data --startup-project ./VehicleServiceBooking.API

The application will apply pending Migrations and seed data using the Data Seeder, if you want to apply it sooner you can use the command below:

dotnet ef database update --project ./VehicleServiceBooking.Data --startup-project ./VehicleServiceBooking.API

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2. Application Layer

Implement Domain Transfer Objects for the Data Models:

• Service Type Dto
• Appointment Dto

Implement the following service classes:

Whilst implementing your services, you should use libraries like AutoMapper to help make Mapping more consistent and configurable.

ServiceTypeService

• GetAllAsync() — retrieve all service types and map to ServiceTypeDto
• GetByIdAsync(id) — retrieve by ID and map to ServiceTypeDto

AppointmentService

• CreateAsync(CreateAppointmentRequest request) must enforce the following business rules before persisting:

  Rule	Detail
  VIN length	Must be exactly 17 characters
  Business hours	Must be Monday to Friday, 08:00–17:00
  Hour slots	Must be on an exact hour (e.g. 09:00, not 09:30)
  No double-booking	Slot must not already be taken for the same service type

• UpdateAsync(int id, UpdateAppointmentRequest request) must apply the same validation rules as CreateAsync.

• CancelAsync(int id) — delegate to the repository and return the result.

You can use private helper methods for your validation logic

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3. API Layer

The endpoint empty classes have been templated, you will need to make the endpoints below:

• ServiceTypeEndpoints.cs — create a GET endpoint with exception handling which catches 401 Not Found

• AppointmentEndpoints.cs — create both POST and PUT endpoints to allow Appointments to be made and updated, both endpoints should check for validation failes and return a 400 Bad Request response with a descriptive message.

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4. Tests

The test class is scaffolded with the following cases — implement each one:

Either NUnit or Moq can be used

Test	Description
CreateAsync_ShouldThrow_WhenVINIsNot17Characters	Invalid VIN should throw
CreateAsync_ShouldThrow_WhenSlotIsOutsideBusinessHours	7pm slot should throw
CreateAsync_ShouldThrow_WhenSlotIsOnAWeekend	Saturday slot should throw
CreateAsync_ShouldThrow_WhenSlotIsAlreadyTaken	Taken slot should throw
CreateAsync_ShouldReturnAppointmentDto_WhenRequestIsValid	Happy path
CancelAsync_ShouldReturnFalse_WhenAppointmentDoesNotExist	Missing ID
CancelAsync_ShouldReturnTrue_WhenAppointmentExists	Happy path

Run the tests with:

dotnet test

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Running the Application

The appsettings.Development.json has been setup with a default SQLite connection string you can change this if you wish, then run using your IDE of choice or:

cd VehicleServiceBooking.API
dotnet run

Swagger UI will be available at:

• https://localhost:7212/swagger/index.html or
• http://localhost:5274/swagger/index.html