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Support freestanding @Test functions in transpiled tests #212

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Merged
marcprux merged 1 commit into from
Mar 12, 2026
Merged

Support freestanding @Test functions in transpiled tests #212

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91 changes: 70 additions & 21 deletions Sources/SkipSyntax/Kotlin/KotlinUnitTestTransformer.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
/// 1. **XCTest**: Classes inheriting from `XCTestCase` with `test`-prefixed methods
/// 2. **Swift Testing**: Functions annotated with `@Test` and types annotated with `@Suite`
///
/// In both cases, JUnit `@Test` annotations and the AndroidJUnit4 runner annotation are applied.
/// In both cases, JUnit `@Test` annotation is applied.
/// Async test functions are wrapped with coroutine test dispatchers.
///
/// - Seealso: `SkipUnit/XCTest.kt`
Expand All @@ -19,6 +19,8 @@ final class KotlinUnitTestTransformer: KotlinTransformer {
/// Types annotated with `@Suite` in Swift source.
private var swiftTestingSuites: [Source.FilePath: Set<String>] = [:]

static let testRunnerAnnotation: String? = nil // was: "@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)"

func gather(from syntaxTree: SyntaxTree) {
var testFunctions: Set<String> = []
var suiteTypes: Set<String> = []
Expand Down Expand Up @@ -73,27 +75,36 @@ final class KotlinUnitTestTransformer: KotlinTransformer {
}

private func visit(_ node: KotlinSyntaxNode, codebaseInfo: CodebaseInfo.Context, testFuncNames: Set<String>, importPackages: inout Set<String>) -> VisitResult<KotlinSyntaxNode> {
if let functionDeclaration = node as? KotlinFunctionDeclaration, let owningClass = functionDeclaration.parent as? KotlinClassDeclaration {
// Check for XCTest-style test functions (name-based detection)
let isXCTest = Self.isXCTestFunction(functionDeclaration, owningClass: owningClass, codebaseInfo: codebaseInfo)
// Check for Swift Testing @Test functions (attribute-based detection)
let isSwiftTesting = testFuncNames.contains(functionDeclaration.name)

if isXCTest || isSwiftTesting {
if functionDeclaration.apiFlags.options.contains(.async) {
transformAsyncTest(functionDeclaration: functionDeclaration, owningClass: owningClass, importPackages: &importPackages)
} else {
functionDeclaration.annotations += ["@Test"]
}
let testRunner = "@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)"
if !owningClass.annotations.contains(testRunner) {
owningClass.annotations += [testRunner]
}
// For Swift Testing @Suite types that don't extend XCTestCase,
// make them implement the XCTestCase interface for assertion access
if isSwiftTesting && !isXCTest {
ensureXCTestCaseConformance(owningClass)
if let functionDeclaration = node as? KotlinFunctionDeclaration {
if let owningClass = functionDeclaration.parent as? KotlinClassDeclaration {
// Check for XCTest-style test functions (name-based detection)
let isXCTest = Self.isXCTestFunction(functionDeclaration, owningClass: owningClass, codebaseInfo: codebaseInfo)
// Check for Swift Testing @Test functions (attribute-based detection)
let isSwiftTesting = testFuncNames.contains(functionDeclaration.name)

if isXCTest || isSwiftTesting {
if functionDeclaration.apiFlags.options.contains(.async) {
transformAsyncTest(functionDeclaration: functionDeclaration, owningClass: owningClass, importPackages: &importPackages)
} else {
functionDeclaration.annotations += ["@Test"]
}
if let testRunnerAnnotation = Self.testRunnerAnnotation {
if !owningClass.annotations.contains(testRunnerAnnotation) {
owningClass.annotations += [testRunnerAnnotation]
}
}
// For Swift Testing @Suite types that don't extend XCTestCase,
// make them implement the XCTestCase interface for assertion access
if isSwiftTesting && !isXCTest {
ensureXCTestCaseConformance(owningClass)
}
return .skip
}
} else if let owningCodeBlock = functionDeclaration.parent as? KotlinCodeBlock,
functionDeclaration.role == .global,
testFuncNames.contains(functionDeclaration.name) {
// Freestanding @Test function — wrap in a generated test class
wrapFreestandingTestFunction(functionDeclaration, in: owningCodeBlock, importPackages: &importPackages)
return .skip
}
}
Expand All @@ -115,6 +126,44 @@ final class KotlinUnitTestTransformer: KotlinTransformer {
}
}

/// Wraps a freestanding `@Test` function in a generated JUnit test class.
/// e.g., `@Test func addition() { ... }` becomes:
/// ```
/// class AdditionTests: XCTestCase {
/// @Test fun addition() { ... }
/// }
/// ```
private func wrapFreestandingTestFunction(_ functionDeclaration: KotlinFunctionDeclaration, in codeBlock: KotlinCodeBlock, importPackages: inout Set<String>) {
// Generate a class name from the function name (e.g., "addition" -> "AdditionTests")
let className = functionDeclaration.name.prefix(1).uppercased() + functionDeclaration.name.dropFirst() + "Tests"

// Create a wrapper class (final, not open)
let classDeclaration = KotlinClassDeclaration(name: className, signature: .named(className, []), declarationType: .classDeclaration)
classDeclaration.modifiers = Modifiers(isFinal: true)
classDeclaration.inherits = [.named("XCTestCase", [])]
if let testRunnerAnnotation = Self.testRunnerAnnotation {
classDeclaration.annotations = [testRunnerAnnotation]
}
classDeclaration.extras = functionDeclaration.extras

// Move the function into the class
if let index = codeBlock.statements.firstIndex(where: { $0 === functionDeclaration }) {
functionDeclaration.role = .member
functionDeclaration.extras = nil
if functionDeclaration.apiFlags.options.contains(.async) {
transformAsyncTest(functionDeclaration: functionDeclaration, owningClass: classDeclaration, importPackages: &importPackages)
} else {
functionDeclaration.annotations += ["@Test"]
}
classDeclaration.members = [functionDeclaration]
functionDeclaration.parent = classDeclaration

codeBlock.statements[index] = classDeclaration
classDeclaration.parent = codeBlock
classDeclaration.assignParentReferences()
}
}

private func transformAsyncTest(functionDeclaration: KotlinFunctionDeclaration, owningClass: KotlinClassDeclaration, importPackages: inout Set<String>) {
importPackages.insert("kotlinx.coroutines.*")
importPackages.insert("kotlinx.coroutines.test.*")
Expand Down
78 changes: 70 additions & 8 deletions Tests/SkipSyntaxTests/TransformerTests.swift
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal open class TestCase: XCTestCase {
@Test
internal open fun testSomeTest() = Unit
Expand Down Expand Up @@ -53,7 +52,6 @@ final class TransformerTests: XCTestCase {

import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal open class TestCase: XCTestCase {

@OptIn(ExperimentalCoroutinesApi::class)
Expand Down Expand Up @@ -88,7 +86,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class MyTests: XCTestCase {
@Test
internal fun addition(): Unit = expectEqual(1 + 1, 2)
Expand All @@ -109,7 +106,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class MyTests: XCTestCase {
@Test
internal fun boolCheck() {
Expand All @@ -132,7 +128,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class MyTests: XCTestCase {
@Test
internal fun inequality(): Unit = expectNotEqual(1, 2)
Expand All @@ -153,7 +148,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class MyTests: XCTestCase {
@Test
internal fun unwrap() {
Expand Down Expand Up @@ -184,7 +178,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class MathTests: XCTestCase {
@Test
internal fun addition(): Unit = expectEqual(2 + 2, 4)
Expand Down Expand Up @@ -212,7 +205,6 @@ final class TransformerTests: XCTestCase {
""", kotlin: """
import skip.unit.*

@org.junit.runner.RunWith(androidx.test.ext.junit.runners.AndroidJUnit4::class)
internal class CompTests: XCTestCase {
@Test
internal fun comparisons() {
Expand All @@ -225,6 +217,76 @@ final class TransformerTests: XCTestCase {
""")
}

func testSwiftTestingFreestandingFunction() async throws {
try await check(swift: """
import Testing

@Test func addition() {
#expect(1 + 2 == 3)
}
""", kotlin: """
import skip.unit.*

internal class AdditionTests: XCTestCase {
@Test
internal fun addition(): Unit = expectEqual(1 + 2, 3)
}
""")
}

func testSwiftTestingMultipleFreestandingFunctions() async throws {
try await check(swift: """
import Testing

@Test func addition() {
#expect(1 + 1 == 2)
}

@Test func subtraction() {
#expect(5 - 3 == 2)
}

func helperNotATest() -> Int {
return 42
}
""", kotlin: """
import skip.unit.*

internal class AdditionTests: XCTestCase {
@Test
internal fun addition(): Unit = expectEqual(1 + 1, 2)
}

internal class SubtractionTests: XCTestCase {
@Test
internal fun subtraction(): Unit = expectEqual(5 - 3, 2)
}

internal fun helperNotATest(): Int = 42
""")
}

func testSwiftTestingFreestandingExpectTrue() async throws {
try await check(swift: """
import Testing

@Test func boolCheck() {
let x = true
#expect(x)
}
""", kotlin: """
import skip.unit.*

internal class BoolCheckTests: XCTestCase {
@Test
internal fun boolCheck() {
val x = true
expectTrue(x)
}
}
""")
}

func testModuleBundleTransformer() async throws {
try await check(swift: """
import Foundation
Expand Down
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