 
 class NetworkClientMutaterTests: XCTestCase {
 
-    var networkClient: NetworkClientMutable!
-
     override func setUp() {
         super.setUp()
-
-        let configuration = NetworkDefaultConfiguration(baseURL: "http://www.mocky.io/")
-        networkClient = NetworkDefaultClient(configuration: configuration, session: .shared)
     }
 
     override func tearDown() {
-        networkClient = nil
         super.tearDown()
+    }
+
+    var networkClient: NetworkDefaultClient {
+        let configuration = NetworkDefaultConfiguration(baseURL: "http://www.mocky.io/")
+        return NetworkDefaultClient(configuration: configuration, session: .shared)
     }
 
     func test_mutaterCalls() {
         let mutater1 = MockEmptyMutater()
         let mutater2 = MockEmptyMutater()
 
+        let networkClient = self.networkClient
         networkClient.addMutater(mutater1)
         networkClient.addMutater(mutater2)
 

            XCTAssertFalse(mutater2.responseReplaceWasCalled)
        }
    }
}

        let mutater0 = MockEmptyMutater()
        let mutater1 = MockMutater()
        let mutater2 = MockEmptyMutater()
        let networkClient = self.networkClient

        networkClient.addMutater(mutater0)
        networkClient.addMutater(mutater1)
