The following document describes the Fable + Suave sample project. You can see it running on azure at http://fable-suave.azurewebsites.net.
- Mono on MacOS/Linux (on Windows .NET Framework is installed by default)
- node.js - JavaScript runtime
- yarn - Package manager for npm modules
On OS X/macOS, make sure you have OpenSSL installed and symlinked correctly, as described here: https://www.microsoft.com/net/core#macos.
dotnet SDK 1.0.4 is required but it'll be downloaded automatically by the build script if not installed (see below). Other tools like Paket or FAKE will also be installed by the build script.
This development stack is designed to be used with minimal tooling. An instance of Visual Studio Code together with the excellent Ionide plugin should be enough.
Start the development mode with:
> build.cmd run // on windows
$ ./build.sh run // on unix
This command will call in build.fsx the target "Run". It will start in parallel:
- dotnet watch run in src/Server (note: Suave is launched on port 8085)
- dotnet fable webpack-dev-server in src/Client (note: the Webpack development server will serve files on http://localhost:8080)
Previously, the build script should download all dependencies like .NET Core SDK, Fable... If you have problems with the download of the .NET Core SDK via the build.cmd or build.sh script, please install the SDK manually from here. Verify
that you have at least SDK version 1.0.4 installed (dotnet --version) and then rerun the build script.
You can now edit files in src/Server or src/Client and recompile + browser refresh will be triggered automatically.
Usually you can just keep this mode running and running. Just edit files, see the browser refreshing and commit + push with git.
The webserver backend is running as a Suave.io service on .NET Core.
In development mode the server is automatically restarted whenever a file in src/Server is saved.
The client is React single page application that uses fable-elmish to provide a scaffold for the code.
The communication to the server is done via HTTPS calls to /api/*. If a user is logged in then a JSON Web Token is sent to the server with every request.
The Fable compiler is used to compile the F# client code to JavaScript so that it can run in the browser.
"Isomorphic F#" started a bit as a joke about Isomorphic JavaScript. The naming is really bad, but the idea to have the same code running on client and server is really interesting.
If you look at src/Server/Shared/Domain.fs then you will see code that is shared between client and server. On the server it is compiled to .NET core and for the client the Fable compiler is translating it into JavaScript.
This is a really convenient technique for a shared domain model.
Start the full build (incl. UI tests) with:
> build.cmd // on windows
$ ./build.sh // on unix
Expecto is a test framework like NUnit or xUnit, but much more developer friendly. With Expecto you write tests as values in normal code. Tests can be composed, reduced, filtered, repeated and passed as values, because they are values. This gives the programmer a lot of leverage when writing tests.
If you are in development mode then you can use Expecto's focused test feature to run a selected test against the running server.
canopy is a F# web automation and testing library, built on top of Selenium. In our expecto suite it looks like the following:
testCase "login with test user" <| fun () ->
url serverUrl
waitForElement ".elmish-app"
click "Login"
"#username" << "test"
"#password" << "test"
click "Log In"
waitForElement "Isaac Abraham"
FAKE is a build automation system with capabilities which are similar to make and rake. It's used to automate the build, test and deployment process. Look into build.fsx for details.
Paket is a dependency manager and allows easier management of the NuGet packages.