Fix email in recipient (#109)

OmiseSwift/API Models/Recipient.swift

@@ -74,7 +74,7 @@ extension Recipient {
         isDefault = try container.decode(Bool.self, forKey: .isDefault)
         failureCode = try container.decodeIfPresent(FailureCode.self, forKey: .failureCode)
         name = try container.decode(String.self, forKey: .name)
-        email = try container.decode(String.self, forKey: .email)
+        email = try container.decode(String?.self, forKey: .email)
         recipientDescription = try container.decodeIfPresent(String.self, forKey: .recipientDescription)
         type = try container.decode(RecipientType.self, forKey: .type)
         taxID = try container.decodeIfPresent(String.self, forKey: .taxID)

OmiseSwiftTests/Fixtures/api.omise.co/recipients-get.json

@@ -48,7 +48,7 @@
       "default": true,
       "active": true,
       "name": "[email protected]",
-      "email": "[email protected]",
+      "email": null,
       "description": "Default recipient",
       "type": "individual",
       "tax_id": "",

OmiseSwiftTests/RecipientOperationFixtureTests.swift

@@ -0,0 +1,24 @@
+import XCTest
+import Omise
+
+class RecipientOperationFixtureTests: FixtureTestCase {
+
+    func testRecipientList() {
+        let expectation = self.expectation(description: "recipient list")
+
+        let request = Recipient.list(using: testClient, params: nil) { (result) in
+            defer { expectation.fulfill() }
+
+            switch result {
+            case let .success(recipientList):
+                XCTAssertEqual(recipientList.data.count, 2)
+            case let .failure(error):
+                XCTFail("\(error)")
+            }
+        }
+
+        XCTAssertNotNil(request)
+        waitForExpectations(timeout: 15.0, handler: nil)
+    }
+
+}