JavaScriptKit and Swift Testing

Related Projects Swift for WebAssembly
1

does JavaScriptKit support Swift Testing?

naïvely, i tried making a Hello World test like this:

import Testing

@Test func test()
{
    let document:JSValue = JSObject.global.document
    let div:JSValue = document.createElement("div")
    div.innerText = "Hello from Swift!"
    _ = document.body.appendChild(div)
}

$ /swift/swift-DEVELOPMENT-SNAPSHOT-2025-03-25-a-ubuntu24.04/usr/bin/swift package \
    --swift-sdk DEVELOPMENT-SNAPSHOT-2025-03-25-a-wasm32-unknown-wasip1-threads \
    js test

error: no such module 'Testing'
 5 | 
 6 | import Testing
   |        `- error: no such module 'Testing'
 7 | 
 8 | @Test func test()
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2

JavaScriptKit's package plugin supports running swift-testing and XCTest test suites. Check this example: JavaScriptKit/Examples/Testing at main · swiftwasm/JavaScriptKit · GitHub

3

that example does not compile for me, if i remove the #if canImport(Testing) gate.

@testable import Counter

import Testing

@Test func increment() async throws {
    var counter = Counter()
    counter.increment()
    #expect(counter.count == 1)
}

@Test func incrementTwice() async throws {
    var counter = Counter()
    counter.increment()
    counter.increment()
    #expect(counter.count == 2)
}

error: no such module 'Testing'
 1 | @testable import Counter
 2 | 
 3 | import Testing
   |        `- error: no such module 'Testing'
 4 | 
 5 | @Test func increment() async throws {
4

Ok, wasm32-unknown-wasip1-threads doesn't support it yet.

1 Like