[FileHandle] Make the function signature the same as DarwinFoundation.

Since `func truncateFile(atOffset offset: UInt64)` has been deprecated, new function is introduced. However, the signatures are different between DarwinFoundation and SwiftFoundation.
Resolves https://bugs.swift.org/browse/SR-11922 .

Author: YOCKOW

Foundation/FileHandle.swift

@@ -570,7 +570,7 @@ open class FileHandle : NSObject {
     }
 
     @available(swift 5.0)
-    public func truncate(toOffset offset: UInt64) throws {
+    public func truncate(atOffset offset: UInt64) throws {
         guard self != FileHandle._nulldeviceFileHandle else { return }
 
         guard _isPlatformHandleValid else { throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileWriteUnknown.rawValue) }
@@ -683,9 +683,9 @@ open class FileHandle : NSObject {
         try! seek(toOffset: offset)
     }
 
-    @available(swift, deprecated: 100000, renamed: "truncate(toOffset:)")
+    @available(swift, deprecated: 100000, renamed: "truncate(atOffset:)")
     open func truncateFile(atOffset offset: UInt64) {
-        try! truncate(toOffset: offset)
+        try! truncate(atOffset: offset)
     }
 
     @available(swift, deprecated: 100000, renamed: "synchronize()")

TestFoundation/TestFileHandle.swift

@@ -342,26 +342,26 @@ class TestFileHandle : XCTestCase {
     }
 #endif
 
-    func test_truncateFile() {
+    func test_truncateFile() throws {
         let url: URL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(ProcessInfo.processInfo.globallyUniqueString, isDirectory: false)
-        _ = FileManager.default.createFile(atPath: url.path, contents: Data())
+        XCTAssertTrue(FileManager.default.createFile(atPath: url.path, contents: Data()))
         defer { _ = try? FileManager.default.removeItem(at: url) }
 
         let fh: FileHandle = FileHandle(forUpdatingAtPath: url.path)!
 
-        fh.truncateFile(atOffset: 50)
+        try fh.truncate(atOffset: 50)
         XCTAssertEqual(fh.offsetInFile, 50)
 
-        fh.truncateFile(atOffset: 0)
+        try fh.truncate(atOffset: 0)
         XCTAssertEqual(fh.offsetInFile, 0)
 
-        fh.truncateFile(atOffset: 100)
+        try fh.truncate(atOffset: 100)
         XCTAssertEqual(fh.offsetInFile, 100)
 
         fh.write(Data([1, 2]))
         XCTAssertEqual(fh.offsetInFile, 102)
 
-        fh.seek(toFileOffset: 4)
+        try fh.seek(toOffset: 4)
         XCTAssertEqual(fh.offsetInFile, 4)
 
         (0..<20).forEach { fh.write(Data([$0])) }
@@ -370,10 +370,10 @@ class TestFileHandle : XCTestCase {
         fh.seekToEndOfFile()
         XCTAssertEqual(fh.offsetInFile, 102)
 
-        fh.truncateFile(atOffset: 10)
+        try fh.truncate(atOffset: 10)
         XCTAssertEqual(fh.offsetInFile, 10)
 
-        fh.seek(toFileOffset: 0)
+        try fh.seek(toOffset: 0)
         XCTAssertEqual(fh.offsetInFile, 0)
 
         let data = fh.readDataToEndOfFile()