Add tests for changes from #937: ignoring 3rd party load failures whi…

…le redirecting

I didn't realize that `STPRedirectContext` was as well tested as it is. I ran into test
failures when executing on iOS 10 (our CI executes against iOS 11), and realized this
needed to be updated.

Recap of behavior change: only report errors in initial load on iOS 11+, and only if
the latest URL was a `stripe.com` URL.

When unit tests were run against iOS 11, this was still true, and the existing test passed.

This adds two more tests: for pre-iOS 11 and for iOS 11 with a redirect to non-stripe.com.
Both of those cases should not report an error, and should not close the Safari View
Controller.

We don't have `guard-let` in Obj-C, nor can we check `!@available(...)`, but I have
emulated that structure at the beginning of these tests. I think it's worth it, and
Joey didn't think it was unreasonable.

Tests/Tests/STPRedirectContextTest.m

@@ -223,10 +223,54 @@ - (void)testSafariViewControllerRedirectFlow_didFinish {
 
 /**
  After starting a SafariViewController redirect flow,
- when SafariViewController fails to load, RedirectContext's completion block
- and dismiss method should be called.
+ when SafariViewController fails to load the initial page (on iOS < 11.0),
+ RedirectContext's completion block should not be called (SFVC keeps loading)
  */
-- (void)testSafariViewControllerRedirectFlow_failedToLoad {
+- (void)testSafariViewControllerRedirectFlow_failedInitialLoad_preiOS11 {
+    if (@available(iOS 11, *)) {
+        // See testSafariViewControllerRedirectFlow_failedInitialLoad_iOS11Plus
+        // and testSafariViewControllerRedirectFlow_failedInitialLoadAfterRedirect_iOS11Plus
+        return; // Skipping
+    }
+
+    id mockVC = OCMClassMock([UIViewController class]);
+    STPSource *source = [STPFixtures iDEALSource];
+    STPRedirectContext *context = [[STPRedirectContext alloc] initWithSource:source completion:^(__unused NSString *sourceID, __unused NSString *clientSecret, __unused NSError *error) {
+        XCTFail(@"completion called");
+    }];
+    id sut = OCMPartialMock(context);
+
+    OCMReject([sut unsubscribeFromNotifications]);
+    OCMReject([sut dismissPresentedViewController]);
+
+    [sut startSafariViewControllerRedirectFlowFromViewController:mockVC];
+
+    BOOL(^checker)(id) = ^BOOL(id vc) {
+        if ([vc isKindOfClass:[SFSafariViewController class]]) {
+            SFSafariViewController *sfvc = (SFSafariViewController *)vc;
+            // Tell the delegate that the initial load failed. on iOS 10, this is a no-op
+            [sfvc.delegate safariViewController:sfvc didCompleteInitialLoad:NO];
+            return YES;
+        }
+        return NO;
+    };
+    OCMVerify([mockVC presentViewController:[OCMArg checkWithBlock:checker]
+                                   animated:YES
+                                 completion:[OCMArg any]]);
+}
+
+/**
+ After starting a SafariViewController redirect flow,
+ when SafariViewController fails to load the initial page (on iOS 11+ & without redirects),
+ RedirectContext's completion block and dismiss method should be called.
+ */
+- (void)testSafariViewControllerRedirectFlow_failedInitialLoad_iOS11Plus API_AVAILABLE(ios(11)) {
+    if (@available(iOS 11, *)) {}
+    else {
+        // see testSafariViewControllerRedirectFlow_failedInitialLoad_preiOS11
+        return; // Skipping
+    }
+
     id mockVC = OCMClassMock([UIViewController class]);
     STPSource *source = [STPFixtures iDEALSource];
     XCTestExpectation *exp = [self expectationWithDescription:@"completion"];
@@ -258,6 +302,51 @@ - (void)testSafariViewControllerRedirectFlow_failedToLoad {
     [self waitForExpectationsWithTimeout:2 handler:nil];
 }
 
+/**
+ After starting a SafariViewController redirect flow,
+ when SafariViewController fails to load the initial page (on iOS 11+ after redirecting to non-Stripe page),
+ RedirectContext's completion block should not be called (SFVC keeps loading)
+ */
+
+- (void)testSafariViewControllerRedirectFlow_failedInitialLoadAfterRedirect_iOS11Plus API_AVAILABLE(ios(11)) {
+    if (@available(iOS 11, *)) {}
+    else {
+        // see testSafariViewControllerRedirectFlow_failedInitialLoad_preiOS11
+        return; // Skipping
+    }
+
+    id mockVC = OCMClassMock([UIViewController class]);
+    STPSource *source = [STPFixtures iDEALSource];
+    STPRedirectContext *context = [[STPRedirectContext alloc] initWithSource:source completion:^(__unused NSString *sourceID, __unused NSString *clientSecret, __unused NSError *error) {
+        XCTFail(@"completion called");
+    }];
+    id sut = OCMPartialMock(context);
+
+    OCMReject([sut unsubscribeFromNotifications]);
+    OCMReject([sut dismissPresentedViewController]);
+
+    [sut startSafariViewControllerRedirectFlowFromViewController:mockVC];
+
+    BOOL(^checker)(id) = ^BOOL(id vc) {
+        if ([vc isKindOfClass:[SFSafariViewController class]]) {
+            SFSafariViewController *sfvc = (SFSafariViewController *)vc;
+            // before initial load is done, SFVC was redirected to a non-stripe.com domain
+            [sfvc.delegate safariViewController:sfvc
+                    initialLoadDidRedirectToURL:[NSURL URLWithString:@"https://girogate.de"]];
+            // Tell the delegate that the initial load failed.
+            // on iOS 11, with the redirect, this is a no-op
+            [sfvc.delegate safariViewController:sfvc didCompleteInitialLoad:NO];
+            return YES;
+        }
+        return NO;
+    };
+    OCMVerify([mockVC presentViewController:[OCMArg checkWithBlock:checker]
+                                   animated:YES
+                                 completion:[OCMArg any]]);
+
+    [self unsubscribeContext:context];
+}
+
 /**
  After starting a SafariViewController redirect flow,
  when the RedirectContext is cancelled, its dismiss method should be called.