Migrate ArgumentParserUnitTests to Swift Testing

Sources/ArgumentParserTestHelpers/TestHelpers+SwiftTesting.swift

@@ -10,6 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 import ArgumentParser
+import ArgumentParserToolInfo
 import Foundation
 import Testing
 
@@ -200,3 +201,105 @@ public func expectSnapshot(
     return expected
   }
 }
+
+public func expectJSONEqualFromString<T: Codable & Equatable>(
+  actual: String,
+  expected: String,
+  for type: T.Type,
+  sourceLocation: SourceLocation = #_sourceLocation
+) throws {
+  expectEqualStrings(
+    actual: actual,
+    expected: expected,
+    sourceLocation: sourceLocation
+  )
+
+  let actualJSONData = try #require(
+    actual.data(using: .utf8),
+    sourceLocation: sourceLocation
+  )
+  let actualDumpJSON = try JSONDecoder().decode(type, from: actualJSONData)
+
+  let expectedJSONData = try #require(
+    expected.data(using: .utf8),
+    sourceLocation: sourceLocation
+  )
+  let expectedDumpJSON = try JSONDecoder().decode(type, from: expectedJSONData)
+
+  #expect(
+    actualDumpJSON == expectedDumpJSON,
+    sourceLocation: sourceLocation
+  )
+}
+
+public func expectDumpHelp<T: ParsableArguments>(
+  type: T.Type,
+  record: Bool = false,
+  test: String = #function,
+  filePath: StaticString = #filePath,
+  sourceLocation: SourceLocation = #_sourceLocation
+) throws {
+  // TODO: migrate to the following API when the minimum Swift version supports it
+  ///
+  // let error = #expect(throws: (any Error).self) {
+  //     _ = try T.parse(["--experimental-dump-help"])
+  // }
+  // let actual = T.fullMessage(for: error)
+  let actual: String
+  do {
+    _ = try T.parse(["--experimental-dump-help"])
+    Issue.record(
+      "Expected T.parse to throw a help request.",
+      sourceLocation: sourceLocation)
+    return
+  } catch {
+    actual = T.fullMessage(for: error)
+  }
+
+  let apiOutput = T._dumpHelp()
+  expectEqualStrings(
+    actual: actual,
+    expected: apiOutput,
+    sourceLocation: sourceLocation
+  )
+
+  let expected = try expectSnapshot(
+    actual: actual,
+    extension: "json",
+    record: record,
+    test: test,
+    filePath: filePath,
+    sourceLocation: sourceLocation
+  )
+
+  guard let expected else { return }
+
+  try expectJSONEqualFromString(
+    actual: actual,
+    expected: expected,
+    for: ToolInfoV0.self,
+    sourceLocation: sourceLocation
+  )
+}
+
+public func expectDumpHelp(
+  command: String,
+  record: Bool = false,
+  test: String = #function,
+  filePath: StaticString = #filePath,
+  sourceLocation: SourceLocation = #_sourceLocation
+) throws {
+  let actual = try requireExecuteCommand(
+    command: command + " --experimental-dump-help",
+    expected: nil,
+    sourceLocation: sourceLocation
+  )
+  try expectSnapshot(
+    actual: actual,
+    extension: "json",
+    record: record,
+    test: test,
+    filePath: filePath,
+    sourceLocation: sourceLocation
+  )
+}

Tests/ArgumentParserUnitTests/DefaultAsFlagCompletionTests.swift

@@ -2,41 +2,41 @@
 //
 // This source file is part of the Swift Argument Parser open source project
 //
-// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Copyright (c) 2025-2026 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 ArgumentParserTestHelpers
-import XCTest
+import Testing
 
 @testable import ArgumentParser
 
-final class DefaultAsFlagCompletionTests: XCTestCase {
-  func testDefaultAsFlagCompletion_Bash() throws {
+@Suite struct DefaultAsFlagCompletionTests {
+  @Test func defaultAsFlagCompletion_Bash() throws {
     let script = try CompletionsGenerator(
       command: DefaultAsFlagCommand.self, shell: .bash
     )
     .generateCompletionScript()
-    try assertSnapshot(actual: script, extension: "bash")
+    try expectSnapshot(actual: script, extension: "bash")
   }
 
-  func testDefaultAsFlagCompletion_Zsh() throws {
+  @Test func defaultAsFlagCompletion_Zsh() throws {
     let script = try CompletionsGenerator(
       command: DefaultAsFlagCommand.self, shell: .zsh
     )
     .generateCompletionScript()
-    try assertSnapshot(actual: script, extension: "zsh")
+    try expectSnapshot(actual: script, extension: "zsh")
   }
 
-  func testDefaultAsFlagCompletion_Fish() throws {
+  @Test func defaultAsFlagCompletion_Fish() throws {
     let script = try CompletionsGenerator(
       command: DefaultAsFlagCommand.self, shell: .fish
     )
     .generateCompletionScript()
-    try assertSnapshot(actual: script, extension: "fish")
+    try expectSnapshot(actual: script, extension: "fish")
   }
 }
 

Tests/ArgumentParserUnitTests/DefaultAsFlagDumpHelpTests.swift

@@ -2,25 +2,25 @@
 //
 // This source file is part of the Swift Argument Parser open source project
 //
-// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Copyright (c) 2025-2026 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 ArgumentParserTestHelpers
-import XCTest
+import Testing
 
 @testable import ArgumentParser
 
-final class DefaultAsFlagDumpHelpTests: XCTestCase {
-  func testDefaultAsFlagDumpHelp() throws {
-    try assertDumpHelp(type: DefaultAsFlagCommand.self)
+@Suite struct DefaultAsFlagDumpHelpTests {
+  @Test func defaultAsFlagDumpHelp() throws {
+    try expectDumpHelp(type: DefaultAsFlagCommand.self)
   }
 
-  func testDefaultAsFlagWithTransformDumpHelp() throws {
-    try assertDumpHelp(type: DefaultAsFlagWithTransformCommand.self)
+  @Test func defaultAsFlagWithTransformDumpHelp() throws {
+    try expectDumpHelp(type: DefaultAsFlagWithTransformCommand.self)
   }
 }
 

Tests/ArgumentParserUnitTests/DumpHelpGenerationTests.swift

@@ -2,45 +2,53 @@
 //
 // This source file is part of the Swift Argument Parser open source project
 //
-// Copyright (c) 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2020-2026 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 ArgumentParserTestHelpers
-import XCTest
+import Testing
 
 @testable import ArgumentParser
 
-final class DumpHelpGenerationTests: XCTestCase {
-  public func testADumpHelp() throws {
-    try assertDumpHelp(type: A.self)
+@Suite struct DumpHelpGenerationTests {
+  @Test func aDumpHelp() throws {
+    try expectDumpHelp(type: A.self)
   }
 
-  public func testBDumpHelp() throws {
-    try assertDumpHelp(type: B.self)
+  @Test func bDumpHelp() throws {
+    try expectDumpHelp(type: B.self)
   }
 
-  public func testCDumpHelp() throws {
-    try assertDumpHelp(type: C.self)
+  @Test func cDumpHelp() throws {
+    try expectDumpHelp(type: C.self)
   }
 
-  func testMathDumpHelp() throws {
-    try assertDumpHelp(command: "math")
+  @Test(
+    .requiresProcessExecution
+  ) func mathDumpHelp() throws {
+    try expectDumpHelp(command: "math")
   }
 
-  func testMathAddDumpHelp() throws {
-    try assertDumpHelp(command: "math add")
+  @Test(
+    .requiresProcessExecution
+  ) func mathAddDumpHelp() throws {
+    try expectDumpHelp(command: "math add")
   }
 
-  func testMathMultiplyDumpHelp() throws {
-    try assertDumpHelp(command: "math multiply")
+  @Test(
+    .requiresProcessExecution
+  ) func mathMultiplyDumpHelp() throws {
+    try expectDumpHelp(command: "math multiply")
   }
 
-  func testMathStatsDumpHelp() throws {
-    try assertDumpHelp(command: "math stats")
+  @Test(
+    .requiresProcessExecution
+  ) func mathStatsDumpHelp() throws {
+    try expectDumpHelp(command: "math stats")
   }
 }