fix date tests 4

Author: Alessio Arsuffi

Marvin/Date/Date.swift

@@ -36,10 +36,12 @@ public extension Date {
     ///   - format: Date format (ex: "yyyy mm dd")
     ///    default: yyyy mm dd
     ///   - locale: locale identifier, default "it_IT"
+    ///   - timezone: timezone identifier, default: "UTC"
     /// - Returns: a string from date
-    public func string(dateFormat format: String? = "yyyy MM dd", locale: String = "it_IT") -> String {
+    public func string(dateFormat format: String? = "yyyy MM dd", locale: String = "it_IT", timezone: String = "UTC") -> String {
         let dateFormatter = DateFormatter()
         dateFormatter.locale = Locale(identifier: locale)
+        dateFormatter.timeZone = TimeZone(identifier: timezone)
         dateFormatter.dateFormat = format
         return dateFormatter.string(from: self)
     }

MarvinTests/Date/DateTests.swift

@@ -93,6 +93,6 @@ class DateTests: XCTestCase {
         }
 
         let dateString = date.string(dateFormat: "yyyy MM dd HH:mm:ss")
-        XCTAssertEqual(dateString, "2017 11 17 12:55:02")
+        XCTAssertEqual(dateString, "2017 11 17 11:55:02")
     }
 }