Skip to content

How do I test the Server?

Testing your Server code in a SAFE app is just the same as in any other dotnet app, and you can use the same tools and frameworks that you are familiar with. These include all of the usual suspects such as NUnit, XUnit, FSUnit, Expecto, FSCheck, AutoFixture etc.

In this guide we will look at using Expecto, as this is included with the standard SAFE template.

I'm using the standard template

Using the Expecto runner

If you are using the standard template, then there is nothing more you need to do in order to start testing your Server code.

In the tests/Server folder, there is a project named Server.Tests with a single script demonstrating how to use Expecto to test the TODO sample.

In order to run the tests, instead of starting your application using

dotnet run

you should instead use

dotnet run RunTests
This will execute the tests and print the results into the console window.

This method builds and runs the Client test project too, which can be slow. If you want to run the Server tests alone, you can simply navigate to the tests/Server directory and run the project using dotnet run.

Using dotnet test or the Visual Studio Test runner

If you would like to use dotnet tests from the command line or the test runner that comes with Visual Studio, there are a couple of extra steps to follow.

1. Install the Test Adapters

Run the following commands at the root of your solution:

dotnet paket add Microsoft.NET.Test.Sdk -p Server.Tests
dotnet paket add YoloDev.Expecto.TestSdk -p Server.Tests

2. Disable EntryPoint generation

Open your ServerTests.fsproj file and add the following element:


3. Discover tests

To allow your tests to be discovered, you will need to decorate them with a [<Tests>] attribute.

The provided test would look like this:

let server = testList "Server" [
    testCase "Adding valid Todo" <| fun _ ->
        let storage = Storage()
        let validTodo = Todo.create "TODO"
        let expectedResult = Ok ()

        let result = storage.AddTodo validTodo

        Expect.equal result expectedResult "Result should be ok"
        Expect.contains (storage.GetTodos()) validTodo "Storage should contain new todo"

4. Run tests

There are now two ways to run these tests.

From the command line, you can just run

dotnet test tests/Server
from the root of your solution.

Alternatively, if you are using Visual Studio or VS Mac you can make use of the built-in test explorers.

I'm using the minimal template

If you are using the minimal template, you will need to first configure a test project as none are included.

1. Add a test project

Create a .Net 5 console project called Server.Tests in the tests/Server folder.

dotnet new console -lang F# -n Server.Tests -o tests/Server
dotnet sln add tests/Server

2. Reference the Server project

Reference the Server project from the Server.Tests project:

dotnet add tests/Server reference src/Server

3. Add Expecto to the Test project

Run the following command:

dotnet add tests/Server package Expecto

4. Add something to test

Update the Server.fs file in the Server project to extract the message logic from the router like so:

let getMessage () = "Hello from SAFE!"

let webApp =
    router {
        get Route.hello (getMessage () |> json )

5. Add a test

Replace the contents of tests/Server/Program.fs with the following:

open Expecto

let server = testList "Server" [
    testCase "Message returned correctly" <| fun _ ->
        let expectedResult = "Hello from SAFE!"        
        let result = Server.getMessage()
        Expect.equal result expectedResult "Result should be ok"

let main _ = runTests defaultConfig server

6. Run the test

dotnet run -p tests/Server

This will print out the results in the console window

7. Using dotnet test or the Visual Studio Test Explorer

Add the libraries Microsoft.NET.Test.Sdk and YoloDev.Expecto.TestSdk to your Test project, using NuGet.

The way you do this will depend on whether you are using NuGet directly or via Paket. See this recipe for more details.

You can now add [<Test>] attributes to your tests so that they can be discovered, and then run them using the dotnet tooling in the same way as explained earlier for the standard template.