Full Modular Monolith .NET application with Domain-Driven Design approach.
1.1 Purpose of this repository
3.3 API and Module Communication
3.4 Module requests processing CQRS
3.5 Domain Model principles and attributes
This is list of main goals of this repository:
- Showing how you can implement a monolith application in a modular way
- Presentation of the full implementation of an application. This is not another simple application. This is not another proof of concept (PoC). The goal is to present the implementation of an application that would be ready to run in production
- Showing the application of best practices and object-oriented programming principles
- Presentation of the use of design patterns. When, how and why they can be used
- Presentation of some architectural considerations, decisions, approaches
- Presentation of the implementation using Domain-Driven Design approach (tactical patterns)
- Presentation of the implementation of Unit Tests for Domain Model (Testable Design in mind).
This is list of subjects which are out of scope for this repository:
- Business requirements gathering and analysis
- System analysis
- Domain exploration
- Domain distillation
- Domain-Driven Design strategic patterns
- Architecture evaluation, quality attributes analysis
- Integration, system tests
- Project management
- Infrastructure
- Containerization
- Software engineering process, CI/CD
- Deployment process
- Maintenance
- Documentation
The reason for creating this repository is the lack of something similar. Most sample applications on GitHub have at least one issue of the following:
- it is very, very simple - few entities and use cases implemented
- it is not finished (for example there is no authentication, logging, etc..)
- it is poorly designed (in my opinion)
- it is poorly implemented (in my opinion)
- it is not well described
- assumptions and decisions are not clearly explained
- it implements "Orders" domain. Yes, everyone knows this domain, but something different is needed
- is implemented in old technology
- is not maintained
To sum up, there are some very good examples, but there are far too few of them. This repository has the task of filling this gap at some level.
Software architecture should always be created to resolve specific business problems. Software architecture always supports some quality attributes and at the same time does not support others. A lot of other factors influence your software architecture - your team, opinions, preferences, experiences, technical constraints, time, budget etc.
Always functional requirements, quality attributes, technical constraints and other factors should be considered before an architectural decision is made.
Because of the above, the architecture and implementation presented in this repository is one of the many ways to solve some problems. Take from this repository as much as you want, use it as you like but remember to always pick the best solution which is appropriate to the problem class you have.
In this project on the first place I focus on its quality. Create good quality involves a lot of analysis, research and work. It takes a lot of time. If you like this project, learned something or you are using it in your applications, please give it a star ⭐. This is the best motivation for me to continue this work. Thanks!
As it is written above there are very few really good examples of this type of application. If you think this repository makes a difference and is worth it, please share it with your friends and on social networks. I will be extremely grateful.
Definition:
Domain - A sphere of knowledge, influence, or activity. The subject area to which the user applies a program is the domain of the software. Domain-Driven Design Reference, Eric Evans
For the purposes of this project, the meeting groups domain, based on the Meetup system, was selected.
Main reasons for selecting this domain:
- It is common, a lot of people use the Meetup site to organize or attend meetings.
- There is a system for it, so everyone can check how software which supports this domain works
- It is not complex so it is easy to understand
- It is not trivial, there are some business rules and logic. It does not have only CRUD operations
- You don't need much specific domain knowledge as for other domains like financing, banking, medical
- It is not big so it is easier to implement
Meetings
Main business entities are Member, Meeting Group and Meeting. Member can create Meeting Group, be part of Meeting Group or can attend the Meeting.
Meeting Group Member can be an Organizer of this group or normal Member.
Only Organizer of Meeting Group can create new Meeting.
Meeting have attendees, not attendees (Members which declare they will not attend the Meeting) and Members on a Waitlist.
Meeting can have an attendees limit. If the limit is reached, Members can only sign up to Waitlist.
Meeting Attendee can bring guests to a Meeting. Number of guests is an attribute of Meeting. Bringing guests can be not allowed.
Meeting Attendee can have one of two roles : normal Attendee or Host. Meeting must have at least one Host. Host is special role which can edit Meeting information or change attendees list.
Administration
To create new Meeting Group, Member needs to propose this group. Meeting Group Proposal is sent to Administrators. Administrator can accept or reject Meeting Group Proposal. If Meeting Group Proposal is accepted, Meeting Group is created.
Payments
To be able to organize Meetings, the Meeting Group must be paid for. Meeting Group Organizer who is the Payer, must pay some fee according to payment plan.
Additionally, Meeting organizer can set Event Fee. Each Meeting Attendee is obliged to pay a fee. All guests should be paid by Meeting Attendee too.
Users
Each Administrator,Member and Payer is an User. To be an User, User Registration is required and confirmed.
Each User has assigned one or more User Role.
Each User Role has set of Permissions. Permission defines whether User can invoke a particular action.
Definition:
Conceptual Model - A conceptual model is a representation of a system, made of the composition of concepts that are used to help people know, understand, or simulate a subject the model represents. Wikipedia - Conceptual model
Conceptual Model
Conceptual Model focuses on structures and relationships between them. What is more important is behavior and events that occur in our domain.
There are many ways to show behavior and events. One of them is a light technique called Event Storming which is becoming more popular. Below are presented 3 main business processes using this technique : user registration, meeting group creation and meeting organization.
Note: Event Storming is a light, live workshop. Here is presented only one of the possible outputs of this workshop. Even if you are not doing Event Storming workshops, this type of presentation of process can be very valuable to you and your stakeholders.
User Registration process
Meeting Group creation
Meeting organization
Modules description:
- API - REST API application. Very thin, hosting ASP.NET MVC Core application. Main responsibilities are 1. Take request 1. Authenticate and Authorize request (using User Access module) 2. Delegate work to specific module sending Command or Query 3. Return response
- User Access - responsible for users authentication, authorization and registration
- Meetings - implements Meetings Bounded Context: creating meeting groups, meetings
- Administration - implements Administration Bounded Context: implements administrative tasks like meeting group proposal verification
- Payments - implements Payments Bounded Context: implements all functionalities associated with payments
- In Memory Events Bus - Publish/Subscribe implementation to asynchronously integrate all modules using events (Event Driven Architecture).
Key assumptions:
- API doesn't have any application logic.
- API communicates with module using a small interface to send Queries and Commands.
- Each module has its own interface which is used by API.
- Modules communicate each other only asynchronously using Events Bus. Remote Procedure Call is not allowed.
- Each Module has it's own data - in separate schema or database. Shared data is not allowed.
- Module doesn't have dependencies on other modules. Module can have only dependency on integration events assembly of other module (see Module level view).
- Each Module has its own Composition Root. Which implies that each Module has its own Inversion Of Control container.
- API as a host needs to initialize each module. Each module has an initialization method.
- Each module is highly encapsulated. Only required types and members are public - the rest is internal or private.
Each Module consists of the following submodules (assemblies):
- Application - it is main submodule which is responsible for initialization, processing all requests, internal commands, integration events.
- Domain - Domain Model in Domain-Driven Design terms implementation applicable in particular Bounded Context.
- Infrastructure - implementation of infrastructural code like EF configuration and mappings.
- IntegrationEvents - Integration Events contracts which are published to Events Bus. Only this assembly can be shared between other modules.
Note: Application, Domain and Infrastructure assemblies can be merged into one assembly. Some people like horizontal layering or more decomposition, some don't. Implementing Domain Model or Infrastructure in separate assembly gives opportunity to encapsulate it using internal keyword. Sometimes Bounded Context logic is not worth it because it is too simple. As always, be pragmatic and take approach whatever you like.
API communicates with Module only in two places: during module initialization and request processing.
Module initialization
Each module has static Initialize method which is invoked in API Startup class. All configuration needed by this module should be provided as arguments to this method. During initialization all services are configured and Composition Root using Inversion Of Control Container is created.
public static void Initialize(
string connectionString,
IExecutionContextAccessor executionContextAccessor,
ILogger logger,
EmailsConfiguration emailsConfiguration)
{
var moduleLogger = logger.ForContext("Module", "Meetings");
ConfigureCompositionRoot(connectionString, executionContextAccessor, moduleLogger, emailsConfiguration);
QuartzStartup.Initialize(moduleLogger);
EventsBusStartup.Initialize(moduleLogger);
}Requests processing
Each module has the same signature interface exposed to API. It contains 3 methods: to execute command with result, command without result and query.
public interface IMeetingsModule
{
Task<TResult> ExecuteCommandAsync<TResult>(ICommand<TResult> command);
Task ExecuteCommandAsync(ICommand command);
Task<TResult> ExecuteQueryAsync<TResult>(IQuery<TResult> query);
}Note: Some people say that processing of command shouldn't return a result. This is a good approach but sometimes impractical, especially when you create a resource and want to immediately return the ID of this resource. Sometimes, boundary between Command and Query is blurry. One of the examples is AuthenticateCommand - it returns a token but it is not a query (has side effect).
Commands and Queries processing is separated applying architectural style/pattern Command Query Responsibility Segregation (CQRS).
Commands are processed using Write Model which is implemented using DDD tactical patterns:
internal class CreateNewMeetingGroupCommandHandler : ICommandHandler<CreateNewMeetingGroupCommand>
{
private readonly IMeetingGroupRepository _meetingGroupRepository;
private readonly IMeetingGroupProposalRepository _meetingGroupProposalRepository;
internal CreateNewMeetingGroupCommandHandler(
IMeetingGroupRepository meetingGroupRepository,
IMeetingGroupProposalRepository meetingGroupProposalRepository)
{
_meetingGroupRepository = meetingGroupRepository;
_meetingGroupProposalRepository = meetingGroupProposalRepository;
}
public async Task<Unit> Handle(CreateNewMeetingGroupCommand request, CancellationToken cancellationToken)
{
var meetingGroupProposal = await _meetingGroupProposalRepository.GetByIdAsync(request.MeetingGroupProposalId);
var meetingGroup = meetingGroupProposal.CreateMeetingGroup();
await _meetingGroupRepository.AddAsync(meetingGroup);
return Unit.Value;
}
}Queries are processed using Read Model which is implemented by executing raw SQL statements on database views:
internal class GetAllMeetingGroupsQueryHandler : IQueryHandler<GetAllMeetingGroupsQuery, List<MeetingGroupDto>>
{
private readonly ISqlConnectionFactory _sqlConnectionFactory;
internal GetAllMeetingGroupsQueryHandler(ISqlConnectionFactory sqlConnectionFactory)
{
_sqlConnectionFactory = sqlConnectionFactory;
}
public async Task<List<MeetingGroupDto>> Handle(GetAllMeetingGroupsQuery request, CancellationToken cancellationToken)
{
var connection = _sqlConnectionFactory.GetOpenConnection();
const string sql = "SELECT " +
"[MeetingGroup].[Id], " +
"[MeetingGroup].[Name], " +
"[MeetingGroup].[Description], " +
"[MeetingGroup].[LocationCountryCode], " +
"[MeetingGroup].[LocationCity]" +
"FROM [meetings].[v_MeetingGroups] AS [MeetingGroup]";
var meetingGroups = await connection.QueryAsync<MeetingGroupDto>(sql);
return meetingGroups.AsList();
}
}Key advantages:
- Solution appropriate to the problem - reading and writing needs are usually different
- Supports SRP - one handler does one thing
- Supports ISP - each handler implements interface with exactly one method
- Commands and Queries are objects (Parameter Object pattern) which are easy to serialize/deserialize
- Easy way to apply Decorator pattern to handle cross-cutting concerns.
- Louse coupling - introduction of Mediator pattern separates invoker of request from handler of request.
One disadvantage - introduction of mediation gives more indirection and is harder to reason about which class handles the request.
More info can be found here: Simple CQRS implementation with raw SQL and DDD
Domain Model, which is the central and most critical part in the system, should be designed with special attention. Here are some key principles and attributes which are applied to Domain Models of each module:
- High level of encapsulation
All members are private by default, then internal, only at the very end public.
- High level of PI (Persistence Ignorance)
No dependencies to infrastructure, databases, other stuff. All classes are POCO.
- Rich in behavior
All business logic is located in Domain Model. No leaks to application layer or other places.
- Low level of primitive obsession
Primitive attributes of Entites grouped together using ValueObjects.
- Business language
All classes, methods and other members named in business language used in this Bounded Context.
- Testable
Domain Model is a critical part of the system so it should be easy to test (Testable Design).
public class MeetingGroup : Entity, IAggregateRoot
{
public MeetingGroupId Id { get; private set; }
private string _name;
private string _description;
private MeetingGroupLocation _location;
private MemberId _creatorId;
private List<MeetingGroupMember> _members;
private DateTime _createDate;
private DateTime? _paymentDateTo;
internal static MeetingGroup CreateBasedOnProposal(
MeetingGroupProposalId meetingGroupProposalId,
string name,
string description,
MeetingGroupLocation location, MemberId creatorId)
{
return new MeetingGroup(meetingGroupProposalId, name, description, location, creatorId);
}
public Meeting CreateMeeting(
string title,
MeetingTerm term,
string description,
MeetingLocation location,
int? attendeesLimit,
int guestsLimit,
Term rsvpTerm,
MoneyValue eventFee,
List<MemberId> hostsMembersIds,
MemberId creatorId)
{
this.CheckRule(new MeetingCanBeOrganizedOnlyByPayedGroupRule(_paymentDateTo));
this.CheckRule(new MeetingHostMustBeAMeetingGroupMemberRule(creatorId, hostsMembersIds, _members));
return new Meeting(this.Id,
title,
term,
description,
location,
attendeesLimit,
guestsLimit,
rsvpTerm,
eventFee,
hostsMembersIds,
creatorId);
}To support Single Responsibility Principle and Don't Repeat Yourself principles, implementation of cross-cutting concerns is done using Decorator Pattern. Each Command processing is decorated by 3 decorators: logging, validation and unit of work.
Logging
Logging decorator logs execution, arguments and processing of each Command. This way each log inside processing has log context of processing command.
internal class LoggingCommandHandlerDecorator<T> : ICommandHandler<T> where T:ICommand
{
private readonly ILogger _logger;
private readonly IExecutionContextAccessor _executionContextAccessor;
private readonly ICommandHandler<T> _decorated;
public LoggingCommandHandlerDecorator(
ILogger logger,
IExecutionContextAccessor executionContextAccessor,
ICommandHandler<T> decorated)
{
_logger = logger;
_executionContextAccessor = executionContextAccessor;
_decorated = decorated;
}
public async Task<Unit> Handle(T command, CancellationToken cancellationToken)
{
if (command is IRecurringCommand)
{
return await _decorated.Handle(command, cancellationToken);
}
using (
LogContext.Push(
new RequestLogEnricher(_executionContextAccessor),
new CommandLogEnricher(command)))
{
try
{
this._logger.Information(
"Executing command {Command}",
command.GetType().Name);
var result = await _decorated.Handle(command, cancellationToken);
this._logger.Information("Command {Command} processed successful", command.GetType().Name);
return result;
}
catch (Exception exception)
{
this._logger.Error(exception, "Command {Command} processing failed", command.GetType().Name);
throw;
}
}
}
private class CommandLogEnricher : ILogEventEnricher
{
private readonly ICommand _command;
public CommandLogEnricher(ICommand command)
{
_command = command;
}
public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
{
logEvent.AddOrUpdateProperty(new LogEventProperty("Context", new ScalarValue($"Command:{_command.Id.ToString()}")));
}
}
private class RequestLogEnricher : ILogEventEnricher
{
private readonly IExecutionContextAccessor _executionContextAccessor;
public RequestLogEnricher(IExecutionContextAccessor executionContextAccessor)
{
_executionContextAccessor = executionContextAccessor;
}
public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
{
if (_executionContextAccessor.IsAvailable)
{
logEvent.AddOrUpdateProperty(new LogEventProperty("CorrelationId", new ScalarValue(_executionContextAccessor.CorrelationId)));
}
}
}
}Validation
Validation decorator performs Command data validation. It checks rules against Command arguments. It uses FluentValidation library to do it.
internal class ValidationCommandHandlerDecorator<T> : ICommandHandler<T> where T:ICommand
{
private readonly IList<IValidator<T>> _validators;
private readonly ICommandHandler<T> _decorated;
public ValidationCommandHandlerDecorator(
IList<IValidator<T>> validators,
ICommandHandler<T> decorated)
{
this._validators = validators;
_decorated = decorated;
}
public Task<Unit> Handle(T command, CancellationToken cancellationToken)
{
var errors = _validators
.Select(v => v.Validate(command))
.SelectMany(result => result.Errors)
.Where(error => error != null)
.ToList();
if (errors.Any())
{
var errorBuilder = new StringBuilder();
errorBuilder.AppendLine("Invalid command, reason: ");
foreach (var error in errors)
{
errorBuilder.AppendLine(error.ErrorMessage);
}
throw new InvalidCommandException(errorBuilder.ToString(), null);
}
return _decorated.Handle(command, cancellationToken);
}
}Unit Of Work
Every Command processing has side effects. To not call commit on every handler, UnitOfWorkCommandHandlerDecorator is used. It additionally marks InternalCommand as processed (if it is Internal Command) and dispatches all Domain Events (as part of Unit Of Work).
public class UnitOfWorkCommandHandlerDecorator<T> : ICommandHandler<T> where T:ICommand
{
private readonly ICommandHandler<T> _decorated;
private readonly IUnitOfWork _unitOfWork;
private readonly MeetingsContext _meetingContext;
public UnitOfWorkCommandHandlerDecorator(
ICommandHandler<T> decorated,
IUnitOfWork unitOfWork,
MeetingsContext meetingContext)
{
_decorated = decorated;
_unitOfWork = unitOfWork;
_meetingContext = meetingContext;
}
public async Task<Unit> Handle(T command, CancellationToken cancellationToken)
{
await this._decorated.Handle(command, cancellationToken);
if (command is InternalCommandBase)
{
var internalCommand =
await _meetingContext.InternalCommands.FirstOrDefaultAsync(x => x.Id == command.Id,
cancellationToken: cancellationToken);
if (internalCommand != null)
{
internalCommand.ProcessedDate = DateTime.UtcNow;
}
}
await this._unitOfWork.CommitAsync(cancellationToken);
return Unit.Value;
}
}Integration between modules takes place only in an asynchronous way using Integration Events and In Memory Events Bus as broker. In this way coupling between modules is minimal and exists only on structure of Integration Events.
Modules don't share data so it is not possible or desirable to create a transaction which spans more than one module. To ensure maximum reliability, Outbox / Inbox pattern are used. They provide accordingly "At-Least-Once delivery" and "At-Least-Once processing".
Outbox and Inbox is implemented using two SQL tables and background worker for each module. Background worker is implemented using Quartz.NET library.
Saving to Outbox:
Processing Outbox:
The main principle of this system is that you can change its state only by calling a specific Command.
Sometimes, Command can be called not by API but by processing module itself. The main use case which uses this mechanism is data processing in eventual consistency mode, when we want to process something in a different process and transaction. This applies for example to Inbox processing, because we want to do something (calling a Command) based on Integration Event from Inbox.
This idea is taken from Alberto's Brandolini Event Storming picture called "The picture that explains “almost” everything" which shows that every side effect (domain event) is created by invoking Command on Aggregate. See EventStorming cheat sheet article for more details.
Implementation of internal processing is very similar to implementation of Outbox and Inbox. One SQL table and one background worker for processing. Each internally processing Command must inherit from InternalCommandBase class:
internal abstract class InternalCommandBase : ICommand
{
public Guid Id { get; }
protected InternalCommandBase(Guid id)
{
this.Id = id;
}
}This is important because UnitOfWorkCommandHandlerDecorator must mark internal Command as processed during committing:
public async Task<Unit> Handle(T command, CancellationToken cancellationToken)
{
await this._decorated.Handle(command, cancellationToken);
if (command is InternalCommandBase)
{
var internalCommand =
await _meetingContext.InternalCommands.FirstOrDefaultAsync(x => x.Id == command.Id,
cancellationToken: cancellationToken);
if (internalCommand != null)
{
internalCommand.ProcessedDate = DateTime.UtcNow;
}
}
await this._unitOfWork.CommitAsync(cancellationToken);
return Unit.Value;
}Authentication
Authentication is implemented using JWT Token and Bearer scheme using IdentityServer. For now, only one authentication method is implemented (forms authentication by providing login and password). It requires implementation of IResourceOwnerPasswordValidator interface:
public class ResourceOwnerPasswordValidator : IResourceOwnerPasswordValidator
{
private readonly IUserAccessModule _userAccessModule;
public ResourceOwnerPasswordValidator(IUserAccessModule userAccessModule)
{
_userAccessModule = userAccessModule;
}
public async Task ValidateAsync(ResourceOwnerPasswordValidationContext context)
{
var authenticationResult = await _userAccessModule.ExecuteCommandAsync(new AuthenticateCommand(context.UserName, context.Password));
if (!authenticationResult.IsAuthenticated)
{
context.Result = new GrantValidationResult(
TokenRequestErrors.InvalidGrant,
authenticationResult.AuthenticationError);
return;
}
context.Result = new GrantValidationResult(
authenticationResult.User.Id.ToString(),
"forms",
authenticationResult.User.Claims);
}
}Authorization
Authorization mechanism implements RBAC (Role Based Access Control) using Permissions. Permissions are more granular and much better way to secure your application than Roles. Each User has a set of Roles and each Role contains one or more Permission. With this mapping User has set of Permissions which are always checked on Controller level:
[HttpPost]
[Route("")]
[HasPermission(MeetingsPermissions.ProposeMeetingGroup)]
public async Task<IActionResult> ProposeMeetingGroup(ProposeMeetingGroupRequest request)
{
await _meetingsModule.ExecuteCommandAsync(
new ProposeMeetingGroupCommand(
request.Name,
request.Description,
request.LocationCity,
request.LocationCountryCode));
return Ok();
}Definition:
A unit test is an automated piece of code that invokes the unit of work being tested, and then checks some assumptions about a single end result of that unit. A unit test is almost always written using a unit testing framework. It can be written easily and runs quickly. It’s trustworthy, readable, and maintainable. It’s consistent in its results as long as production code hasn’t changed. Art of Unit Testing 2nd Edition Roy Osherove
Attributes of good unit test
- Automated
- Maitainable
- Runs very fast (in ms)
- Consistent, Deterministic (always the same result)
- Isolated from other tests
- Readable
- Can be executed by anyone
- Testing public API, not internal behavior (overspecification)
- Looks like production code
- Treated as production code
Implementation
Each unit test has 3 standard sections: Arrange, Act and Assert
- Arrange
The Arrange section is responsible for preparing the Aggregate for testing the public method that we want to test. This public method is often called from the unit tests perspective as SUT (system under test).
Creating an Aggregate ready for testing involves calling one or more other public constructors/methods on the Domain Model. At first it may seem that we are testing too many things at the same time, but this is not true. We need to be one hundred percent sure, that the Aggregate is in a state exactly as it will be in production. This can only be ensured when:
- we use only public API of Domain Model
- we don't use InternalsVisibleToAttribute class. This exposes Domain Model to Unit Tests library removing encapsulation so our tests and production code is treated differently and it is a very bad thing.
- we don't use ConditionalAttribute classes. It reduces readability and increases complexity.
- we don't create any special constructors/factory methods for tests (even with conditional compilation symbols). Special constructor/factory method only for unit tests causes duplication of business logic in the test itself and focuses on state. Additionally, this kind of approach causes the test to be very sensitive to changes and hard to maintain.
- We don't remove encapsulation from Domain Model (for example: change keywords from internal/private to public)
- We don't make methods protected to inherit from tested class and in this way provide access to internal methods/properties.
Isolation of external dependencies
There are 2 main concepts - stubs and mocks:
A stub is a controllable replacement for an existing dependency (or collaborator) in the system. By using a stub, you can test your code without dealing with the dependency directly.
A mock object is a fake object in the system that decides whether the unit test has passed or failed. It does so by verifying whether the object under test called the fake object as expected. There’s usually no more than one mock per test. Art of Unit Testing 2nd Edition Roy Osherove
Good advice is following: use stubs if you need to, but try to avoid mocks. Mocking causes us to test too many internal things and leads to overspecification.
- Act
This section is very easy - we execute exactly one public method on aggregate (SUT).
- Assert
In this section we check expectations. There are only 2 possible outcomes:
- Method completed and Domain Event was published (or many) or
- Business rule was broken
Simple example:
[Test]
public void NewUserRegistration_WithUniqueLogin_IsSuccessful()
{
// Arrange
var usersCounter = Substitute.For<IUsersCounter>();
// Act
var userRegistration =
UserRegistration.RegisterNewUser(
"login", "password", "test@email",
"firstName", "lastName", usersCounter);
// Assert
var newUserRegisteredDomainEvent = AssertPublishedDomainEvent<NewUserRegisteredDomainEvent>(userRegistration);
Assert.That(newUserRegisteredDomainEvent.UserRegistrationId, Is.EqualTo(userRegistration.Id));
}
[Test]
public void NewUserRegistration_WithoutUniqueLogin_BreaksUserLoginMustBeUniqueRule()
{
// Arrange
var usersCounter = Substitute.For<IUsersCounter>();
usersCounter.CountUsersWithLogin("login").Returns(x => 1);
// Assert
AssertBrokenRule<UserLoginMustBeUniqueRule>(() =>
{
// Act
UserRegistration.RegisterNewUser(
"login", "password", "test@email",
"firstName", "lastName", usersCounter);
});
}Advanced example:
[Test]
public void AddAttendee_WhenMemberIsAlreadyAttendeeOfMeeting_IsNotPossible()
{
// Arrange
var creatorId = new MemberId(Guid.NewGuid());
var meetingTestData = CreateMeetingTestData(new MeetingTestDataOptions
{
CreatorId = creatorId
});
var newMemberId = new MemberId(Guid.NewGuid());
meetingTestData.MeetingGroup.JoinToGroupMember(newMemberId);
meetingTestData.Meeting.AddAttendee(meetingTestData.MeetingGroup, newMemberId, 0);
// Assert
AssertBrokenRule<MemberCannotBeAnAttendeeOfMeetingMoreThanOnceRule>(() =>
{
// Act
meetingTestData.Meeting.AddAttendee(meetingTestData.MeetingGroup, newMemberId, 0);
});
}CreateMeetingTestData method is an implementation of SUT Factory described by Mark Seemann which allows keeping common creation logic in one place:
protected MeetingTestData CreateMeetingTestData(MeetingTestDataOptions options)
{
var proposalMemberId = options.CreatorId ?? new MemberId(Guid.NewGuid());
var meetingProposal = MeetingGroupProposal.ProposeNew(
"name", "description",
new MeetingGroupLocation("Warsaw", "PL"), proposalMemberId);
meetingProposal.Accept();
var meetingGroup = meetingProposal.CreateMeetingGroup();
meetingGroup.UpdatePaymentInfo(DateTime.Now.AddDays(1));
var meetingTerm = options.MeetingTerm ??
new MeetingTerm(DateTime.UtcNow.AddDays(1), DateTime.UtcNow.AddDays(2));
var rsvpTerm = options.RvspTerm ?? Term.NoTerm;
var meeting = meetingGroup.CreateMeeting("title",
meetingTerm,
"description",
new MeetingLocation("Name", "Address", "PostalCode", "City"),
options.AttendeesLimit,
options.GuestsLimit,
rsvpTerm,
MoneyValue.Zero,
new List<MemberId>(),
proposalMemberId);
DomainEventsTestHelper.ClearAllDomainEvents(meetingGroup);
return new MeetingTestData(meetingGroup, meeting);
}List of technologies, frameworks and libraries used for implementation:
- .NET Core 2.2 (platform)
- MS SQL Server Express (database)
- Entity Framework Core 2.2 (ORM Write Model implementation for DDD)
- Autofac (Inversion of Control Container)
- IdentityServer4 (Authentication and Authorization)
- Serilog (structured logging)
- Hellang.Middleware.ProblemDetails (API Problem Details support)
- Swashbuckle (Swagger automated documentation)
- Dapper (micro ORM for Read Model)
- Newtonsoft.Json (serialization/deserialization to/from JSON)
- Quartz.NET (background processing)
- FluentValidation (data validation)
- MediatR (mediator implementation)
- Postman (API tests)
- NUnit (Testing framework)
- NSubstitute (Testing isolation framework)
- Visual Paradigm Community Edition (CASE tool for modeling and documentation)
- Download and install .NET Core 2.2 SDK
- Download and install MS SQL Server Express or other
- Create empty database and run
script
- Set connection string to database in appsettings.json file or using Secrets
This project is still under analysis and development. I assume its maintenance for a long time. I would appreciate if you would like to contribute to it. Please let me know, create an Issue or Pull Request.
List of features/tasks/approaches to add:
| Name | Priority | Status | Release date |
|---|---|---|---|
| Domain Model Unit Tests | High | Completed | 2019-09-10 |
| API automated tests | Normal | ||
| FrontEnd SPA application | Normal | ||
| Meeting comments feature | Low | ||
| Notifications feature | Low | ||
| Messages feature | Low | ||
| Migration to .NET Core 3.0 | Low | ||
| More advanced Payments module | Low |
NOTE: Please don't hesitate to suggest something else or change to existing code. All proposals will be considered.
Kamil Grzybek
Blog: https://kamilgrzybek.com
Twitter: https://twitter.com/kamgrzybek
LinkedIn: https://www.linkedin.com/in/kamilgrzybek/
GitHub: https://github.com/kgrzybek
The project is under MIT license.