Fable.Jester4

Fable 4 bindings for jest and friends for delightful Fable testing:

• fast-check
• jest-dom
• react-testing-library
• user-event
• testing-playground

A quick look:

Jest.describe("my tests", fun () ->
    Jest.test("water is wet", fun () ->
        Jest.expect("test").toBe("test")
        Jest.expect("test").not.toBe("somethingElse")
        Jest.expect("hi").toHaveLength(2)
        Jest.expect("hi").not.toHaveLength(3)
    )
    Jest.test.prop("Is positive", Arbitrary.ConstrainedDefaults.integer(1,100), fun i ->
        Jest.expect(i).toBeGreaterThan(0)
    )
)

Latest Release (v0.34.0)

🎉 Fable 4 Support

This release upgrades all packages to support Fable 4, bringing improved performance and better JavaScript output.

📦 Updated Dependencies

• Fable.Core: 3.x → 4.x
• Fable.Promise: 2.x → 3.x
• Feliz: 1.x → 2.x

⚠️ Breaking Changes

When upgrading to v0.34.0, you will need to:

1. Upgrade to Fable 4 - Install Fable 4 as a .NET tool:

   dotnet tool install fable --local

2. Update your dependencies - Update your paket.dependencies or package references to use:

   • Fable.Core >= 4.0.0
   • Fable.Promise >= 3.0.0
   • Feliz >= 2.0.0 (if using Fable.ReactTestingLibrary4)
   • Replace old packages with new ones:
     • Fable.Jester → Fable.Jester4
     • Fable.FastCheck → Fable.FastCheck4
     • Fable.FastCheck.Jest → Fable.FastCheck4.Jest
     • Fable.ReactTestingLibrary → Fable.ReactTestingLibrary4

3. Update your code - Update namespace imports in your F# files:

   // Old:
   open Fable.Jester
   open Fable.FastCheck
   open Fable.ReactTestingLibrary
   
   // New:
   open Fable.Jester4
   open Fable.FastCheck4
   open Fable.ReactTestingLibrary4

4. Update build scripts - Replace fable-splitter commands with dotnet fable:

   # Old:
   fable-splitter -c splitter.config.js
   
   # New:
   dotnet fable <project-path> -o <output-dir>

🔧 Additional Changes

• Added int64 overloads for Jest.expect to prevent implicit decimal conversions
• Fixed type compatibility issues with Browser.Types in Fable 4

Full documentation can be found here.