[Issue #1672] Added Request retryCount property to support RequestRetrier.

By adding the retryCount to the Request, the RequestRetrier protocol can use the retryCount to determine whether to continue to retry the Request.

Source/Request.swift

@@ -110,6 +110,9 @@ open class Request {
     /// The response received from the server, if any.
     open var response: HTTPURLResponse? { return task?.response as? HTTPURLResponse }
 
+    /// The number of times the request has been retried.
+    open internal(set) var retryCount: UInt = 0
+
     let originalTask: TaskConvertible?
 
     var startTime: CFAbsoluteTime?

Source/SessionManager.swift

@@ -769,6 +769,7 @@ open class SessionManager {
 
             request.delegate.task = task // resets all task delegate data
 
+            request.retryCount += 1
             request.startTime = CFAbsoluteTimeGetCurrent()
             request.endTime = nil
 

Tests/SessionManagerTests.swift

@@ -562,7 +562,7 @@ class SessionManagerTestCase: BaseTestCase {
         var response: DataResponse<Any>?
 
         // When
-        sessionManager.request("https://httpbin.org/basic-auth/user/password")
+        let request = sessionManager.request("https://httpbin.org/basic-auth/user/password")
             .validate()
             .responseJSON { jsonResponse in
                 response = jsonResponse
@@ -574,6 +574,7 @@ class SessionManagerTestCase: BaseTestCase {
         // Then
         XCTAssertEqual(handler.adaptedCount, 2)
         XCTAssertEqual(handler.retryCount, 2)
+        XCTAssertEqual(request.retryCount, 1)
         XCTAssertEqual(response?.result.isSuccess, false)
     }
 
@@ -590,7 +591,7 @@ class SessionManagerTestCase: BaseTestCase {
         var response: DataResponse<Any>?
 
         // When
-        sessionManager.request("https://httpbin.org/basic-auth/user/password")
+        let request = sessionManager.request("https://httpbin.org/basic-auth/user/password")
             .validate()
             .responseJSON { jsonResponse in
                 response = jsonResponse
@@ -602,6 +603,7 @@ class SessionManagerTestCase: BaseTestCase {
         // Then
         XCTAssertEqual(handler.adaptedCount, 2)
         XCTAssertEqual(handler.retryCount, 1)
+        XCTAssertEqual(request.retryCount, 1)
         XCTAssertEqual(response?.result.isSuccess, true)
     }
 
@@ -618,7 +620,7 @@ class SessionManagerTestCase: BaseTestCase {
         var response: DataResponse<Any>?
 
         // When
-        sessionManager.request("https://httpbin.org/basic-auth/user/password")
+        let request = sessionManager.request("https://httpbin.org/basic-auth/user/password")
             .validate()
             .responseJSON { jsonResponse in
                 response = jsonResponse
@@ -630,6 +632,7 @@ class SessionManagerTestCase: BaseTestCase {
         // Then
         XCTAssertEqual(handler.adaptedCount, 1)
         XCTAssertEqual(handler.retryCount, 1)
+        XCTAssertEqual(request.retryCount, 0)
         XCTAssertEqual(response?.result.isSuccess, false)
 
         if let error = response?.result.error as? AFError {