Test: Enable most AsyncProcessTests

Package.swift

@@ -795,11 +795,17 @@ let package = Package(
                 "Archiver/Inputs/invalid_archive.tar.gz",
                 "Archiver/Inputs/invalid_archive.zip",
                 "processInputs/long-stdout-stderr",
+                "processInputs/long-stdout-stderr.bat",
                 "processInputs/exit4",
+                "processInputs/exit4.bat",
                 "processInputs/simple-stdout-stderr",
+                "processInputs/simple-stdout-stderr.bat",
                 "processInputs/deadlock-if-blocking-io",
+                "processInputs/deadlock-if-blocking-io.bat",
                 "processInputs/echo",
+                "processInputs/echo.bat",
                 "processInputs/in-to-out",
+                "processInputs/in-to-out.bat",
             ]
         ),
         .testTarget(

Sources/Basics/Concurrency/AsyncProcess.swift

@@ -387,6 +387,20 @@ package final class AsyncProcess {
         self.loggingHandler = loggingHandler ?? AsyncProcess.loggingHandler
     }
 
+    package convenience init(
+        args: [String],
+        environment: Environment = .current,
+        outputRedirection: OutputRedirection = .collect,
+        loggingHandler: LoggingHandler? = .none
+    ) {
+        self.init(
+            arguments: args,
+            environment: environment,
+            outputRedirection: outputRedirection,
+            loggingHandler: loggingHandler
+        )
+    }
+
     package convenience init(
         args: String...,
         environment: Environment = .current,

Sources/_InternalTestSupport/Process.swift

@@ -0,0 +1,49 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See http://swift.org/LICENSE.txt for license information
+ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
+ */
+
+public import Foundation
+
+public enum OperatingSystem: Hashable, Sendable {
+    case macOS
+    case windows
+    case linux
+    case android
+    case unknown
+}
+
+extension ProcessInfo {
+    #if os(macOS)
+    public static let hostOperatingSystem = OperatingSystem.macOS
+    #elseif os(Linux)
+    public static let hostOperatingSystem = OperatingSystem.linux
+    #elseif os(Windows)
+    public static let hostOperatingSystem = OperatingSystem.windows
+    #else
+    public static let hostOperatingSystem = OperatingSystem.unknown
+    #endif
+
+    #if os(Windows)
+    public static let EOL = "\r\n"
+    #else
+    public static let EOL = "\n"
+    #endif
+
+    #if os(Windows)
+    public static let exeSuffix = ".exe"
+    #else
+    public static let exeSuffix = ""
+    #endif
+
+    #if os(Windows)
+    public static let batSuffix = ".bat"
+    #else
+    public static let batSuffix = ""
+    #endif
+}