Developer guide

This section goes over the setup of the repo for development.

Repo setup

Install Node.js 20 LTS
Install pnpm

npm install -g pnpm

Install dependencies

pnpm install

Build the dependencies

pnpm build

(Optional) Install Playwright browsers for UI testing

npx playwright install

Start the build in watch mode to automatically rebuild on save

pnpm run watch

Using command line

If you are not at the root of the repo you have to use -w option to specify you want to run the command for the workspace. pnpm -w <command>. Those commands can be run on the workspace or in a specific package(cd ./packages/<pkg>).

Command	Description
`pnpm build`	Build
`pnpm test`	Test
`pnpm test:watch`	Run test in watch mode(only when inside a package)
`pnpm watch`	Build in watch mode, Starting this command will rebuild the typescript files on save.
`pnpm clean`	Clean, sometimes there are ghost files left in the dist folder (common when renaming or deleting a TypeScript file), running this will get a clean state.
`pnpm format`	Format
`pnpm format:check`	Validate files are formatted
`pnpm gen-extern-signature`	Regenerate TypeScript signature for decorators(except compiler)
`pnpm change add`	Add a change description
`pnpm lint`	Run linters
`pnpm lint:fix`	Fix autofixable issues
`pnpm regen-samples`	Regen the samples(when the samples test fail)
`pnpm regen-docs`	Regen the reference docs

Verbose test logging

Tests sometimes log extra info using logVerboseTestOutput To see this output on the command line, set environment variable TYPESPEC_VERBOSE_TEST_OUTPUT=true.

For the compiler you will need to run it manually or run the whole workspace build. This is because for the tool to run it needs the compiler to build first.

Using VS Code

Recommended extensions

Vitest Test Explorer: Run tests from the IDE.
Prettier: Automatically keep code formatted correctly on save.
ESLint: Show eslint errors in warnings in UI.
Code Spell Checker: Show spell check errors in document.

Opening the repo as workspace

Always open the root of the repo as the workspace. Things are setup to allow easy development across packages rather than opening one package at a time in the IDE.

File -> Open Workspace, select root folder where the TypeSpec repo was cloned
Or run code /path/to/repo/root on the command line

Building

Terminal -> Run Build Task (Ctrl+Shift+B)

This will setup a an incremental watching build for the whole repo. From there on, your changes will be built whenever you save.

Problems will be reported in the Problems pane automatically and the Terminal pane will have three parallel watch tasks running:

watch-source: tsc process that recompile on TypeScript changes
watch-spec: process that regenerates spec.html when spec.emu.html changes
watch-tmlanguage: process that regenerates typespec.tmlanguage when tmlanguage.ts changes

Testing

# Run all the tests
pnpm test

# Run in a specific package tests in watch mode
pnpm test:watch

Debugging

There are several "Run and Debug" tasks set up. Click on the Run and Debug icon on the sidebar, pick one from its down, and press F5 to debug the last one you chose.

VS Code Extension: This will run and debug an experimental instance of VS Code with the TypeSpec extension for VS Code and TypeSpec language server running live with any of your changes. It will attach to both the VS Code client process and the language server process automatically.
Compile Scratch: Use this to debug compiling packages/samples/scratch/*.tsp. The TypeSpec source code in that folder is excluded from source control by design. Create TypeSpec files there to experiment and debug how the compiler reacts.
Compile Scratch (nostdlib): Same as above, but skips parsing and evaluating the TypeSpec standard library. Sometimes it's easier to
Attach to Default Port: Use this to attach to a manually run node --debug command.
Attach to Language Server: Use this to attach to the language server process of an already running client process. Useful if you want to debug the language server in VS Code while debugging the VS client in VS.
Regenerate .tmlanguage: This runs the code that produces the typespec.tmlanguage file that provides syntax highlighting of TypeSpec in VS and VS Code. Select this to debug its build process.

Developing the Visual Studio Extension

Prerequisites

Install Visual Studio 17.0 or later. It is not currently possible to build the VS extension without it, and of course you'll need Visual Studio to run and debug the Visual Studio extension.

Build VS extension on the command line

See the command line build steps above. If you have VS installed, the VS extension will be included in your command line full repo builds automatically.

If you do not have VS installed the command line build steps above will simply skip building the VS extension and only build the VS Code extension.

Build VS extension in VS

Open packages/typespec-vs/Microsoft.TypeSpec.VisualStudio.sln in Visual Studio
Build -> Build solution (Ctrl+Shift+B)

Unlike TypeScript in VS Code above, this is not a watching build, but it is relatively fast to run. Press Ctrl+Shift+B again to build any changes after you make them.

Debug VS extension

Click on the play icon in the toolbar or press F5

This will run and debug an experimental instance of VS with a version of the TypeSpec extension for VS Code running live with any of your changes to the extension or the TypeSpec language server.

The VS debugger will attach only to the VS client process. Use "Attach to Language Server" described above to debug the language server in VS Code.

Installing your build

pnpm dogfood

This will globally install the @typespec/compiler package, putting your build of typespec on PATH, and install the VS Code extension if VS Code is installed.

Note the important difference between this and the steps to run and debug the VS Code extension above: the dogfood command installs the TypeSpec extension with your changes in regular, non-experimental instance of VS Code, meaning you will have it always, and not only when running the debug steps above. This is exactly like using tsp vscode install, only instead of downloading the latest release, it uses a build with your changes applied.

There is no automatic dogfood process for installing the VS extension non-experimentally, but if you build the typespec-vs project from the command line following the steps above, or build its Release configuration in Visual Studio, then you can install it by double-clicking on packages/typespec-vs/Microsoft.TypeSpec.VisualStudio.vsix that gets produced.

TypeSpec website

Run locally

Go to packages/website and run the command:

pnpm start

Pull request

Trigger TypeSpec Playground Try It build

For contributors of the repo the build will trigger automatically but for other's forks it will need a manual trigger from a contributor. As a contributor you can run the following command to trigger the build and create a TypeSpec playground link for this PR.

/azp run typespec - pr tools

Issue and Pr processes

Triage process

Each team might use their own way of triaging issues however figuring out the area is a common process.

flowchart TD
    classDef bot fill:#69f
    classDef user fill:#9c6


    subgraph "Legend"
      a([User action])
      b[\Automation detect/]:::bot
      c[Automation action]:::bot
      d{{state}}
    end

    subgraph "Issue creation"
        select_template([User select template])

        select_template --> bug_template
        select_template --> feature_template
        select_template --> plain

        bug_template([Bug]) --> add_bug_label[🤖 add `bug` label]:::bot --> start
        feature_template([Feature]) --> add_feature_label["🤖 add `feature` label"]:::bot --> start
        plain([Plain]) --> start
        start{{"✅ Issue created"}}
    end



    subgraph "Area triage"
        auto-triage[\🤖 Detect if issue has area checkbox/]:::bot
        add-needs-area[🤖 label 'needs-area']:::bot
        auto-area-label["🤖 label '{area}'"]:::bot
        add-area-label(["Issue is labelled with {area}"])
        remove-needs-area[🤖 Remove 'needs-area']:::bot
    end

    subgraph "Team triage"

        team-triage{{Issue Labeled with Team area}}
        team-triage -- wrong area --> remove_area([Remove area label])
        team-triage -- correct area --> triage([Triage/add to project])

    end




    start --> auto-triage

    auto-triage -- no --> add-needs-area
    auto-triage -- yes --> auto-area-label

    auto-area-label --> remove-needs-area

    add-needs-area --> add-area-label
    add-area-label --> remove-needs-area
    remove-needs-area ---> team-triage
    remove_area --> add-needs-area

Loading

Labels

TypeSpec repo use labels to help categorize and manage issues and PRs. The following is a list of labels and their descriptions.

Labels reference

area

Area of the codebase

Name	Color	Description
`compiler:core`	#453261	Issues for @typespec/compiler
`compiler:emitter-framework`	#453261	Issues for the emitter framework
`ide`	#846da1	Issues for VS, VSCode, Monaco, etc.
`lib:http`	#c7aee6
`lib:openapi`	#c7aee6
`lib:rest`	#c7aee6
`lib:versioning`	#c7aee6
`meta:blog`	#007dc8	Blog updates
`meta:website`	#007dc8	TypeSpec.io updates
`tspd`	#004185	Issues for the tspd tool
`emitter:client:csharp`	#e1b300	Issue for the C# client emitter: @typespec/http-client-csharp
`emitter:client:java`	#e1b300	Issue for the Java client emitter: @typespec/http-client-java
`emitter:client:python`	#e1b300	Issue for the Python client emitter: @typespec/http-client-python
`emitter:json-schema`	#957300
`emitter:protobuf`	#957300	The protobuf emitter
`emitter:openapi3`	#957300	Issues for @typespec/openapi3 emitter
`openapi3:converter`	#957300	Issues for @typespec/openapi3 openapi to typespec converter
`emitter:service:csharp`	#967200
`emitter:service:js`	#967200
`emitter:service:java`	#967200	Issue for Java service emitter
`eng`	#65bfff
`ui:playground`	#3256a8
`ui:type-graph-viewer`	#3256a8

issue_kinds

Issue kinds

Name	Color	Description
`bug`	#d93f0b	Something isn't working
`feature`	#cccccc	New feature or request
`docs`	#cccccc	Improvements or additions to documentation
`epic`	#cccccc

breaking-change

Labels around annotating issues and PR if they contain breaking change or deprecation

Name	Color	Description
`breaking-change`	#B60205	A change that might cause specs or code to break
`deprecation`	#760205	A previously supported feature will now report a warning and eventually be removed

design-issues

Design issue management

Name	Color	Description
`design:accepted`	#1a4421	Proposal for design has been discussed and accepted.
`design:needed`	#96c499	A design request has been raised that needs a proposal
`design:proposed`	#56815a	Proposal has been added and ready for discussion

process

Process labels

Name	Color	Description
`needs-area`	#ffffff
`needs-info`	#ffffff	Mark an issue that needs reply from the author or it will be closed automatically
`stale`	#ffffff	Mark a PR that hasn't been recently updated and will be closed.
`triaged:core`	#5319e7

misc

Misc labels

Name	Color	Description
`Client Emitter Migration`	#FD92F0
`good first issue`	#7057ff	Good for newcomers
`mq`	#0969da	Good candidate for MQ

Updating labels

Labels are configured in eng/common/config/labels.ts. To update labels, edit this file and run pnpm sync-labels. If you create a new label in github UI without updating the labels.ts file, it WILL be automatically removed

TypeSpec Emitters

The various language emitters will live in the in the repo under the following directory structure

packages/{protocol}-{client|server}-{language} - Contains the @typespec/{protocol}-{client|server}-{language} package which is intended to be consumed by customers in their tsconfig.yaml file.
packages/{protocol}-{client|server}-{language}-generator - Contains the @typespec/{protocol}-{client|server}-{language}-generator package which is the backend implementation of for a given emitter and usually contains code languages such as .NET, Python, or Java. This package is only intended to be used as a dependency of the root emitter package.
packages/{protocol}-{client|server}-{language}-generator\** - This directory will contain whatever is needed to build the backend emitter code generator. It will contain whatever folder structure is needed to build that specific native code. It will also contain an isolated ci.yml file which will be the build pipeline for this package.

There is a goal to be able to ship these emitter packages independent from the rest of the packages in this repo as such they by default be excluded from the root pnpm workspace. Any npm package work will be isolated to those directories with a goal of eventually moving to a consistent model so that we can both work in isolation as well as work as a E2E.

For language specific contributing information look for the contributing.md file in that specific lanague emitter folder.

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CONTRIBUTING.md

CONTRIBUTING.md

Developer guide

Repo setup

Using command line

Verbose test logging

Using VS Code

Recommended extensions

Opening the repo as workspace

Building

Testing

Debugging

Developing the Visual Studio Extension

Prerequisites

Build VS extension on the command line

Build VS extension in VS

Debug VS extension

Installing your build

TypeSpec website

Run locally

Pull request

Trigger TypeSpec Playground Try It build

Issue and Pr processes

Triage process

Labels

Labels reference

area

issue_kinds

breaking-change

design-issues

process

misc

Updating labels

TypeSpec Emitters

Files

CONTRIBUTING.md

Latest commit

History

CONTRIBUTING.md

File metadata and controls

Developer guide

Repo setup

Using command line

Verbose test logging

Using VS Code

Recommended extensions

Opening the repo as workspace

Building

Testing

Debugging

Developing the Visual Studio Extension

Prerequisites

Build VS extension on the command line

Build VS extension in VS

Debug VS extension

Installing your build

TypeSpec website

Run locally

Pull request

Trigger TypeSpec Playground Try It build

Issue and Pr processes

Triage process

Labels

Labels reference

area

issue_kinds

breaking-change

design-issues

process

misc

Updating labels

TypeSpec Emitters