Support Swift Testing in Test helpers

CMakeLists.txt

@@ -26,6 +26,7 @@ if(NOT APPLE)
   find_package(Foundation CONFIG)
   if(BUILD_TESTING)
     find_package(XCTest CONFIG)
+    find_package(Testing CONFIG)
   endif()
 endif()
 

Sources/ArgumentParserTestHelpers/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_library(ArgumentParserTestHelpers
-  TestHelpers.swift)
+  TestHelpers.swift
+  TestHelpers+SwiftTesting.swift)
 set_target_properties(ArgumentParserTestHelpers PROPERTIES
   INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_Swift_MODULE_DIRECTORY})
 target_link_libraries(ArgumentParserTestHelpers PUBLIC
@@ -13,3 +14,7 @@ if(XCTest_Found)
   target_link_libraries(ArgumentParserTestHelpers PUBLIC
     XCTest)
 endif()
+if(Testing_FOUND)
+  target_link_libraries(ArgumentParserTestHelpers PUBLIC
+    Testing)
+endif()

Sources/ArgumentParserTestHelpers/TestHelpers+SwiftTesting.swift

@@ -0,0 +1,68 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift Argument Parser open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+//
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+import Testing
+
+public func expectResultFailure<T, U: Error>(
+  _ expression: @autoclosure () -> Result<T, U>,
+  _ message: @autoclosure () -> String = "",
+  sourceLocation: SourceLocation = #_sourceLocation
+) {
+  AssertResultFailure(expression(), message(), sourceLocation: sourceLocation)
+}
+
+public func expectErrorMessage<A: ParsableArguments>(
+  _ type: A.Type, _ arguments: [String], _ errorMessage: String,
+  sourceLocation: SourceLocation = #_sourceLocation
+) {
+  AssertErrorMessage(
+    type, arguments, errorMessage, sourceLocation: sourceLocation)
+}
+
+public func expectFullErrorMessage<A: ParsableArguments>(
+  _ type: A.Type, _ arguments: [String], _ errorMessage: String,
+  sourceLocation: SourceLocation = #_sourceLocation
+) {
+  AssertFullErrorMessage(
+    type, arguments, errorMessage, sourceLocation: sourceLocation)
+}
+
+public func expectParse<A: ParsableArguments>(
+  _ type: A.Type, _ arguments: [String],
+  sourceLocation: SourceLocation = #_sourceLocation,
+  closure: (A) throws -> Void
+) {
+  AssertParse(type, arguments, sourceLocation: sourceLocation) {
+    try closure($0)
+  }
+}
+
+public func expectParseCommand<A: ParsableCommand>(
+  _ rootCommand: ParsableCommand.Type, _ type: A.Type, _ arguments: [String],
+  sourceLocation: SourceLocation = #_sourceLocation,
+  closure: (A) throws -> Void
+) {
+  AssertParseCommand(
+    rootCommand, type, arguments, sourceLocation: sourceLocation
+  ) {
+    try closure($0)
+  }
+}
+
+public func expectEqualStrings(
+  actual: String,
+  expected: String,
+  sourceLocation: SourceLocation = #_sourceLocation
+) {
+  AssertEqualStrings(
+    actual: actual, expected: expected, sourceLocation: sourceLocation)
+}

Sources/ArgumentParserTestHelpers/TestHelpers.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserToolInfo
+import Testing
 import XCTest
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
@@ -80,12 +81,20 @@ public func AssertResultFailure<T, U: Error>(
   _ expression: @autoclosure () -> Result<T, U>,
   _ message: @autoclosure () -> String = "",
   file: StaticString = #filePath,
-  line: UInt = #line
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation
 ) {
   switch expression() {
   case .success:
     let msg = message()
-    XCTFail(msg.isEmpty ? "Incorrectly succeeded" : msg, file: file, line: line)
+    if Test.current != nil {
+      Issue.record(
+        msg.isEmpty ? "Incorrectly succeeded" : "\(msg)",
+        sourceLocation: sourceLocation)
+    } else {
+      XCTFail(
+        msg.isEmpty ? "Incorrectly succeeded" : msg, file: file, line: line)
+    }
   case .failure:
     break
   }
@@ -94,71 +103,127 @@ public func AssertResultFailure<T, U: Error>(
 // swift-format-ignore: AlwaysUseLowerCamelCase
 public func AssertErrorMessage<A>(
   _ type: A.Type, _ arguments: [String], _ errorMessage: String,
-  file: StaticString = #filePath, line: UInt = #line
+  file: StaticString = #filePath,
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation
 ) where A: ParsableArguments {
+
   do {
     _ = try A.parse(arguments)
-    XCTFail("Parsing should have failed.", file: file, line: line)
+    if Test.current != nil {
+      Issue.record(
+        "Parsing should have failed.", sourceLocation: sourceLocation)
+    } else {
+      XCTFail("Parsing should have failed.", file: file, line: line)
+    }
   } catch {
     // We expect to hit this path, i.e. getting an error:
-    XCTAssertEqual(A.message(for: error), errorMessage, file: file, line: line)
+    if Test.current != nil {
+      #expect(
+        A.message(for: error) == errorMessage,
+        sourceLocation: sourceLocation
+      )
+    } else {
+      XCTAssertEqual(
+        A.message(for: error), errorMessage, file: file, line: line)
+    }
   }
 }
 
 // swift-format-ignore: AlwaysUseLowerCamelCase
 public func AssertFullErrorMessage<A>(
   _ type: A.Type, _ arguments: [String], _ errorMessage: String,
-  file: StaticString = #filePath, line: UInt = #line
+  file: StaticString = #filePath,
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation
 ) where A: ParsableArguments {
   do {
     _ = try A.parse(arguments)
-    XCTFail("Parsing should have failed.", file: (file), line: line)
+    if Test.current != nil {
+      Issue.record(
+        "Parsing should have failed.", sourceLocation: sourceLocation)
+    } else {
+      XCTFail("Parsing should have failed.", file: (file), line: line)
+    }
   } catch {
     // We expect to hit this path, i.e. getting an error:
-    XCTAssertEqual(
-      A.fullMessage(for: error), errorMessage, file: (file), line: line)
+    if Test.current != nil {
+      #expect(
+        A.fullMessage(for: error) == errorMessage,
+        sourceLocation: sourceLocation
+      )
+    } else {
+      XCTAssertEqual(
+        A.fullMessage(for: error), errorMessage, file: (file), line: line)
+    }
   }
 }
 
 // swift-format-ignore: AlwaysUseLowerCamelCase
 public func AssertParse<A>(
   _ type: A.Type, _ arguments: [String], file: StaticString = #filePath,
-  line: UInt = #line, closure: (A) throws -> Void
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation,
+  closure: (A) throws -> Void
 ) where A: ParsableArguments {
   do {
     let parsed = try type.parse(arguments)
     try closure(parsed)
   } catch {
     let message = type.message(for: error)
-    XCTFail("\"\(message)\" — \(error)", file: (file), line: line)
+    if Test.current != nil {
+      Issue.record(
+        "\"\(message)\" — \(error)",
+        sourceLocation: sourceLocation
+      )
+    } else {
+      XCTFail("\"\(message)\" — \(error)", file: (file), line: line)
+    }
   }
 }
 
 // swift-format-ignore: AlwaysUseLowerCamelCase
 public func AssertParseCommand<A: ParsableCommand>(
   _ rootCommand: ParsableCommand.Type, _ type: A.Type, _ arguments: [String],
-  file: StaticString = #filePath, line: UInt = #line,
+  file: StaticString = #filePath,
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation,
   closure: (A) throws -> Void
 ) {
   do {
     let command = try rootCommand.parseAsRoot(arguments)
     guard let aCommand = command as? A else {
-      XCTFail(
-        "Command is of unexpected type: \(command)", file: (file), line: line)
+      if Test.current != nil {
+        Issue.record(
+          "Command is of unexpected type: \(command)",
+          sourceLocation: sourceLocation
+        )
+      } else {
+        XCTFail(
+          "Command is of unexpected type: \(command)", file: (file), line: line)
+      }
       return
     }
     try closure(aCommand)
   } catch {
     let message = rootCommand.message(for: error)
-    XCTFail("\"\(message)\" — \(error)", file: file, line: line)
+    if Test.current != nil {
+      Issue.record(
+        "\"\(message)\" — \(error)",
+        sourceLocation: sourceLocation
+      )
+    } else {
+      XCTFail("\"\(message)\" — \(error)", file: file, line: line)
+    }
   }
 }
 
 // swift-format-ignore: AlwaysUseLowerCamelCase
 public func AssertParseCommandErrorMessage<A: ParsableCommand>(
   _ rootCommand: ParsableCommand.Type, _ type: A.Type, _ arguments: [String],
   _ errorMessage: String,
-  file: StaticString = #filePath, line: UInt = #line
+  file: StaticString = #filePath,
+  line: UInt = #line
 ) {
   do {
     let command = try rootCommand.parseAsRoot(arguments)
@@ -179,7 +244,8 @@ public func AssertEqualStrings(
   actual: String,
   expected: String,
   file: StaticString = #filePath,
-  line: UInt = #line
+  line: UInt = #line,
+  sourceLocation: SourceLocation = #_sourceLocation
 ) {
   // Normalize line endings to '\n'.
   let actual =
@@ -248,10 +314,17 @@ public func AssertEqualStrings(
       """
   }
 
-  XCTFail(
-    "Actual output does not match the expected output:\n\(stringComparison)",
-    file: file,
-    line: line)
+  if Test.current != nil {
+    Issue.record(
+      "Actual output does not match the expected output:\n\(stringComparison)",
+      sourceLocation: sourceLocation
+    )
+  } else {
+    XCTFail(
+      "Actual output does not match the expected output:\n\(stringComparison)",
+      file: file,
+      line: line)
+  }
 }
 
 // swift-format-ignore: AlwaysUseLowerCamelCase

Tests/ArgumentParserEndToEndTests/CustomParsingEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class ParsingEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/DefaultAsFlagEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class DefaultAsFlagEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/DefaultSubcommandEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParserTestHelpers
 import ArgumentParserToolInfo
+import Testing
 import XCTest
 
 @testable import ArgumentParser
@@ -132,7 +133,7 @@ extension DefaultSubcommandEndToEndTests {
     }
   }
 
-  func testNotMyParent() throws {
+  func testNotMyParent() {
     AssertParseCommandErrorMessage(
       MyCommand.self, BadParent.self, ["--verbose", "bad-parent"],
       "Command 'Other' is not a parent of the current command.")

Tests/ArgumentParserEndToEndTests/DefaultsEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class DefaultsEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/EnumEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class EnumEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/EqualsEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class EqualsEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/FlagsEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class FlagsEndToEndTests: XCTestCase {

Tests/ArgumentParserEndToEndTests/JoinedEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class JoinedEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/LongNameWithShortDashEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class LongNameWithSingleDashEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/NestedCommandEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class NestedCommandEndToEndTests: XCTestCase {}

Tests/ArgumentParserEndToEndTests/OptionGroupEndToEndTests.swift

@@ -11,6 +11,7 @@
 
 import ArgumentParser
 import ArgumentParserTestHelpers
+import Testing
 import XCTest
 
 final class OptionGroupEndToEndTests: XCTestCase {}