developer-guide.md

Developer Guide

Prerequisites

In order to build and test the .NET Core Command-line Interface (CLI), you need the following installed on you machine:

For Windows

1. git (available from the Git Website) on the PATH.

For Linux

1. git (available from your package manager or the Git Website) on the PATH.

For macOS

1. git (available from Homebrew or the Git Website) on the PATH.

Building

Windows

Run the following command from the root of the repository:

build.cmd

The build script will output a dotnet installation to artifacts\bin\redist\Debug\dotnet that will include any local changes to the .NET Core CLI.

As part of the build, some intermediate files will get generated which may run into long-path issues. If you encounter a build failure with an error message similar to Resource file [filename].resx cannot be found., enable long paths and try again.

To open the solution in Visual Studio, be sure to build with build.cmd and run the generated environment for your shell. If you're using cmd, then run artifacts\sdk-build-env.bat. If you're using powershell, you need to 'dot source' artifacts/sdk-build-env.ps1. Finally, open Visual Studio with devenv sdk.sln.

In addition, Visual Studio must have the following option set:

Go to Tools -> Options to make sure "Use previews of the .NET SDK (requires restart)" is checked and restart VS.

Linux and macOS

Run the following command from the root of the repository:

./build.sh

The build script will output a .NET Core installation to artifacts\bin\redist\Debug\dotnet that will include any local changes to the .NET Core CLI.

Running tests

Windows

Run the following command from the root of the repository to run all the .NET Core CLI tests:

build.cmd -test

Linux and macOS

Run the following command from the root of the repository to run all the .NET Core CLI tests:

./build.sh --test

Using the built dotnet

The dotnet executable in the artifacts directory can be run directly.

However, it's easier to configure a test environment to run the built dotnet. This test environment is managed by dogfood. The dogfood script starts a new Powershell with the environment configured to redirect SDK resolution to your build.

From that shell your SDK will be available in:

• any Visual Studio instance launched (via & devenv.exe)
• dotnet build
• msbuild

Windows

Run the following commands from the root of the repository to setup the test environment:

eng\dogfood.cmd

Ensure the dotnet being used is from the artifacts directory:

where dotnet

This should output ..\artifacts\bin\redist\Debug\dotnet\dotnet.exe.

You can now run dotnet commands to test changes.

Linux and macOS

Run the following commands from the root of the repository to setup the test environment:

source ./eng/dogfood.sh

Ensure the dotnet being used is from the artifacts directory:

which dotnet

This should output .../artifacts/bin/redist/Debug/dotnet/dotnet.

You can now run dotnet commands to test changes.

Debugging

Run "dotnet --debug " which will launch dotnet and pause waiting for user input. This will give you time to attach a debugger to the running dotnet process, set the breakpoints you want to stop at in your built copy of the sdk, and then you can hit enter for the dotnet command to continue.

Run tests from the command line

build.cmd # to have a full build first
.\artifacts\sdk-build-env.bat
cd src\Tests\YOURTEST.Tests # cd to the test folder that contains the test csproj file
dotnet test --filter "FullyQualifiedName~TESTNAME" # run individual test

Run tests in Visual Studio

Use developer command prompt for Visual Studio or put devenv on you PATH

build.cmd # to have a full build first
.\artifacts\sdk-build-env.bat
devenv sdk.sln

Note again that in Visual studio "Use previews of the .NET SDK (requires restart)" must be checked. See the above comment for how to enable this.

A simple test

Using the dotnet built in the previous steps:

mkdir test
cd test
dotnet new console
dotnet run

This should print Hello World!.

Locked files

If you see error like error MSB3021: Unable to copy file "toolset-tasks.dll" to "toolset-tasks.dll". The process cannot access the file 'toolset-tasks.dll' because it is being used by another process.

You could run the following to stop all dotnet related processes

taskkill /F /IM dotnet.exe /T ||
taskkill /F /IM VSTest.Console.exe /T ||
taskkill /F /IM msbuild.exe /T

Adding a Command

The dotnet CLI supports several models for adding new commands:

1. In the CLI itself via dotnet.dll.
2. Through a .NET Core Global Tool.
3. Through MSBuild tasks & targets in a NuGet package.
4. Through executables prefixed with dotnet- on the PATH.

Commands in dotnet.dll

Developers are generally encouraged to avoid adding commands to dotnet.dll or the CLI installer directly. This is appropriate for very general commands such as restore, build, publish, test, and clean, but is generally too broad of a distribution mechanism for new commands.

Create an issue and engage the repository maintainers if you feel there is a missing core command that you would like to add.

.NET Core Global Tools

A .NET Core Global Tool can be used to install a dotnet- prefixed tool to the PATH.

The CLI will then treat the remainder of the tool name as a dotnet command. For example, a tool with the name dotnet-hello could be executed by dotnet hello.

MSBuild tasks & targets

NuGet allows adding tasks and targets to a project through a NuGet package. Extending the CLI through this model has several advantages:

1. Targets have access to the MSBuild Project Context, allowing them to reason about the files and properties being used to build a particular project.
2. Targets are not CLI-specific, making them easy to share across command-line and IDE environments

Commands added as targets can be invoked once the target project adds a reference to the containing NuGet package and restores.

Targets are invoked by calling dotnet msbuild /t:{TargetName}

Commands on the PATH

The dotnet CLI considers any executable on the path named dotnet-{commandName} to be a command it can call out to.