Add size property to types that conform to Location

Sources/Files.swift

@@ -105,6 +105,17 @@ public extension Location {
         return storage.attributes[.modificationDate] as? Date
     }
 
+    typealias ByteCount = Int64
+
+    /// The size of the item in bytes, or `nil` if the information is not available.
+    var size: ByteCount? {
+        guard let size = storage.attributes[.size] as? UInt64 else {
+            return nil
+        }
+
+        return ByteCount(size)
+    }
+
     /// Initialize an instance of an existing location at a given path.
     /// - parameter path: The absolute path of the location.
     /// - throws: `LocationError` if the item couldn't be found.

Tests/FilesTests/FilesTests.swift

@@ -540,6 +540,16 @@ class FilesTests: XCTestCase {
             XCTAssertTrue(file.modificationDate.map(Calendar.current.isDateInToday) ?? false)
         }
     }
+
+    func testSize() {
+        performTest {
+            let subfolder = try folder.createSubfolder(named: "Folder")
+            XCTAssertNotNil(subfolder.size)
+
+            let file = try folder.createFile(named: "File")
+            XCTAssertNotNil(file.size)
+        }
+    }
 
     func testParent() {
         performTest {
@@ -906,6 +916,7 @@ class FilesTests: XCTestCase {
         ("testFirstAndLastInFileSequence", testFirstAndLastInFileSequence),
         ("testConvertingFileSequenceToRecursive", testConvertingFileSequenceToRecursive),
         ("testModificationDate", testModificationDate),
+        ("testSize", testSize),
         ("testParent", testParent),
         ("testRootFolderParentIsNil", testRootFolderParentIsNil),
         ("testRootSubfolderParentIsRoot", testRootSubfolderParentIsRoot),