fixup: Move FileDescriptor.fileSize() to an internal extension in SystemTests

Author: simonjbeaumont

Sources/System/FileHelpers.swift

@@ -122,18 +122,4 @@ extension FileDescriptor {
       return .success(buffer.count)
     }
   }
-
-  /// Return the current size of the file.
-  ///
-  /// - Returns: The current size of the file, in bytes.
-  @_alwaysEmitIntoClient
-  @discardableResult
-  public func fileSize(
-    retryOnInterrupt: Bool = true
-  ) throws -> Int64 {
-    let current = try seek(offset: 0, from: .current)
-    let size = try seek(offset: 0, from: .end)
-    try seek(offset: current, from: .start)
-    return size
-  }
 }

Tests/SystemTests/FileDescriptorExtras.swift

@@ -0,0 +1,25 @@
+/*
+ This source file is part of the Swift System open source project
+
+ Copyright (c) 2020 Apple Inc. and the Swift System project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+*/
+
+#if SYSTEM_PACKAGE
+@testable import SystemPackage
+#else
+@testable import System
+#endif
+
+extension FileDescriptor {
+  internal func fileSize(
+    retryOnInterrupt: Bool = true
+  ) throws -> Int64 {
+    let current = try seek(offset: 0, from: .current)
+    let size = try seek(offset: 0, from: .end)
+    try seek(offset: current, from: .start)
+    return size
+  }
+}