Add PromiseKit dependency

- Added PromiseKit dependency

Carthage/Checkouts/PromiseKit/Extensions/StoreKit/Tests/TestStoreKit.m

@@ -0,0 +1,27 @@
+@import PMKStoreKit;
+@import PromiseKit;
+@import StoreKit;
+@import XCTest;
+
+@implementation PMKSKProductsRequest: SKProductsRequest
+
+- (void)start {
+    PMKAfter(0.5).then(^{
+        [self.delegate productsRequest:self didReceiveResponse:[SKProductsResponse new]];
+    });
+}
+
+@end
+
+@implementation SKProductsRequestTests: XCTestCase
+
+- (void)test {
+    id ex = [self expectationWithDescription:@""];
+    SKProductsRequest *rq = [PMKSKProductsRequest new];
+    [rq promise].then(^{
+        [ex fulfill];
+    });
+    [self waitForExpectationsWithTimeout:1 handler:nil];
+}
+
+@end

Carthage/Checkouts/PromiseKit/Extensions/StoreKit/Tests/TestStoreKit.swift

@@ -0,0 +1,22 @@
+import PMKStoreKit
+import PromiseKit
+import StoreKit
+import XCTest
+
+class SKProductsRequestTests: XCTestCase {
+    func test() {
+        class MockProductsRequest: SKProductsRequest {
+            override func start() {
+                after(seconds: 0.1).done {
+                    self.delegate?.productsRequest(self, didReceive: SKProductsResponse())
+                }
+            }
+        }
+
+        let ex = expectation(description: "")
+        MockProductsRequest().start(.promise).done { _ in
+            ex.fulfill()
+        }
+        waitForExpectations(timeout: 1, handler: nil)
+    }
+}