[Windows] Add trailing slash to NSTemporaryDirectory result

NSTemporaryDirectory on Darwin returns path with trailing slash,
and almost every test in TestFileManager counts on it.

Author: lxbndr

Sources/Foundation/NSPathUtilities.swift

@@ -16,13 +16,20 @@ let validPathSeps: [Character] = ["/"]
 #endif
 
 public func NSTemporaryDirectory() -> String {
+    func normalizedPath(with path: String) -> String {
+        if validPathSeps.contains(where: { path.hasSuffix(String($0)) }) {
+            return path
+        } else {
+            return path + String(validPathSeps.last!)
+        }
+    }
 #if os(Windows)
     let cchLength: DWORD = GetTempPathW(0, nil)
     var wszPath: [WCHAR] = Array<WCHAR>(repeating: 0, count: Int(cchLength + 1))
     guard GetTempPathW(DWORD(wszPath.count), &wszPath) <= cchLength else {
       preconditionFailure("GetTempPathW mutation race")
     }
-    return String(decodingCString: wszPath, as: UTF16.self).standardizingPath
+    return normalizedPath(with: String(decodingCString: wszPath, as: UTF16.self).standardizingPath)
 #else
 #if canImport(Darwin)
     let safe_confstr = { (name: Int32, buf: UnsafeMutablePointer<Int8>?, len: Int) -> Int in
@@ -57,11 +64,7 @@ public func NSTemporaryDirectory() -> String {
     }
 #endif
     if let tmpdir = ProcessInfo.processInfo.environment["TMPDIR"] {
-        if !validPathSeps.contains(where: { tmpdir.hasSuffix(String($0)) }) {
-            return tmpdir + "/"
-        } else {
-            return tmpdir
-        }
+        return normalizedPath(with: tmpdir)
     }
 #if os(Android)
     // Bionic uses /data/local/tmp/ as temporary directory. TMPDIR is rarely

Tests/Foundation/Tests/TestFileManager.swift

@@ -24,6 +24,11 @@ class TestFileManager : XCTestCase {
     let pathSep = "/"
 #endif
 
+    func test_NSTemporaryDirectory() {
+        let tempDir = NSTemporaryDirectory()
+        XCTAssertTrue(validPathSeps.contains(where: { tempDir.hasSuffix(String($0)) }), "Temporary directory path must end with path separator")
+    }
+
     func test_createDirectory() {
         let fm = FileManager.default
         let path = NSTemporaryDirectory() + "testdir\(NSUUID().uuidString)"
@@ -1974,6 +1979,7 @@ VIDEOS=StopgapVideos
             /* ⚠️  */ ("test_replacement", testExpectedToFail(test_replacement,
             /* ⚠️  */     "<https://bugs.swift.org/browse/SR-10819> Re-enable Foundation test TestFileManager.test_replacement")),
             ("test_concurrentGetItemReplacementDirectory", test_concurrentGetItemReplacementDirectory),
+            ("test_NSTemporaryDirectory", test_NSTemporaryDirectory),
         ]
 
         #if !DEPLOYMENT_RUNTIME_OBJC && NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT && !os(Android)