LeanCode CoreLibrary

The LeanCode Core Library is a set of helper libraries developed at our company that aids our day-to-day development. Not only does it serve as a facilitator in our day-to-day coding activities, but it also encapsulates comprehensive guidelines, gathers our collective knowledge on application architecture and development best practices.

Our primary objective is to provide a definitive and opinionated framework tailored for .NET Core application development. Within this framework, we've standardized various facets of application design and implementation:

• CQRS (Command Query Responsibility Segregation) and CQRS-as-API: Establishing conventions and practices for implementing CQRS patterns and their representation through APIs.

• Domain-Driven Design (DDD) Models: Defining foundational DDD models and integrating them within the broader framework.

• Integrations with External Services: Pre-defined integrations and guidelines for interfacing with external services, ensuring consistency and reliability.

• Additional Functionalities: Including features such as handling audit logs, facilitating force updates, and localization.

• Tests: Helpers dedicated to aiding and improving the process of writing and executing tests.

While embodying the attributes of a framework, LeanCode Core Library aligns closely with the ASP.NET Core model, emphasizing modularity and minimal intrusion into the application codebase.

Documentation

CoreLibrary documentation is available here.

Versioning

CoreLib version is tricky. Since it is mostly used internally by us at LeanCode, we're not really following Semantic Versioning. Instead, we decide which version is considered stable but maintained, which one is under active development and which one is out of support. There will also be versions that are unmaintained and should be no longer used. There are some vague rules on how we decide what state particular version is in:

1. If there are projects that are not actively worked on, it is maintained but not actively developed,
2. If it is based on old (out of support) .NET Core version, it is unmaintained,
3. If the version is used by active projects only, it is under active development.

Additionally, there are some rules regarding versioning itself and changes to the version number:

1. Since v5, CoreLib major version is the same as .NET major version,
2. Minor version is used as a major version,
3. If CoreLib version is stable, we can't introduce breaking changes without changing version,
4. We allow breaking changes between minor (major) versions,
5. If CoreLib version is under active development, we can introduce breaking changes without version bump,
6. A single CoreLib version cannot be both stable and under active development,
7. There is a small period of time after new CoreLib version is released when we allow all kinds of breakages (i.e. .NET Core bumps if we release during preview window).

Library versions

All of the libraries that are part of the CoreLib are versioned together and require exact version of other libraries. This simplifies versioning substantially but at the expense of flexibility.

Supported versions

Here is the list of available major versions of the library (as of 2022-03-25):

CoreLib	.NET Core	Under development	Stable	Notes
v3.4	2.2			Not published
v4.1	3.1			Unmaintained
v4.2	3.1			Unmaintained
v5.0	5.0			Unmaintained
v5.1	5.0			Unmaintained
v6.0	6.0			Unmaintained
v6.1	6.0			Unmaintained
v7.0	7.0		✔
v8.0	8.0		✔
v8.1	8.0	✔

Building & Testing

Building

dotnet build

Release version

If you want to build release configuration of the library, you need to specify what version the output package will have. That can be done with VERSION environment variable or by passing VERSION as MSBuild parameter to the build command. CI also specifies GIT_COMMIT that is appended to InformationalVersion property of the assemblies to mark exact source code.

Testing

The framework can be unit-tested by cding into test folder and calling

dotnet msbuild /t:RunTests

Moreover, there are some integration-style tests that require external services. They can be tested with docker and docker-compose tools. Currently there is one integration-test suite:

1. test/LeanCode.IntegrationTests,

It has a docker folder that contains necessary configuration. You can run the suite using:

docker-compose run test

Publishing

After successful test, packages can be packed with

dotnet pack -c Release -o $PWD/publish

and then published to NuGet feed with

dotnet nuget push 'publish/*.nupkg'

provided that API Key is correctly specified in profile/machine NuGet.Config.

Project structure

Root structure

The project is divided into the main directories:

1. src with the source code,
2. test with test,
3. benchmarks with benchmarking project,
4. docs with this documentation.

Plus there are some files in the root directory (SLN, config files & READMEs).

Source code structure

The src folder that contains the main source code is then divided into:

1. Core - the bootstrapping part of the CoreLib,
2. Domain - domain model-related projects,
3. Infrastructure - infrastructure-related projects,
4. Helpers - really small helper projects,
5. Testing - testing helpers (e.g. integration tests),
6. Tools - projects that enhance build-time (e.g. contracts gen, .NET Core analyzers).

test folder follows str structure closely.

Build system

CoreLib build system mostly MSBuild-based, with some help of CI system to orchestrate build/test/publish process (see Building & Testing for more details).

We leverage .NET Core's MSBuild Directory.Build.targets files to centrally manage dependency versions. It is forbidden to directly specify Version in csprojs. Instead, one adds simple <ProjectReference Include="NAME" /> and then <ProjectReference Update="NAME" Version="VALID_VERSION" /> in Directory.Build.targets in the CoreLib root. This immensely helps avoiding dependency conflicts down the road.

Besides .targets file, we use central Directory.Build.props to manage some of the project properties. Check /Directory.Build.props, /src/Directory.Build.props and /test/Directory.Build.props what is being centrally set.

Creating new packages

Creating new packages (that will be published to the feed) is simple. You just have to:

1. Create new .NET CoreLibrary project in the correct location,
2. Remove TargetFramework since it is managed externally.

Or you can just modify the following project template (most of the projects use this):

<Project Sdk="Microsoft.NET.Sdk">

</Project>