fix present time race that can occur between viewWillAppear and viewDidAppear

Author: xster

testing/scenario_app/ios/Scenarios/Scenarios/ScreenBeforeFlutter.h

@@ -7,7 +7,7 @@
 @interface ScreenBeforeFlutter : UIViewController
 
 - (id)initWithEngineRunCompletion:(void (^)(void))engineRunCompletion;
-- (FlutterViewController*)showFlutter;
+- (FlutterViewController*)showFlutter:(void (^)(void))showCompletion;
 
 @property(nonatomic, readonly) FlutterEngine* engine;
 

testing/scenario_app/ios/Scenarios/Scenarios/ScreenBeforeFlutter.m

@@ -27,7 +27,7 @@ - (void)viewDidLoad {
   showFlutterButton.tintColor = UIColor.whiteColor;
   showFlutterButton.clipsToBounds = YES;
   [showFlutterButton addTarget:self
-                        action:@selector(showFlutter)
+                        action:@selector(showFlutter:)
               forControlEvents:UIControlEventTouchUpInside];
 
   [self.view addSubview:showFlutterButton];
@@ -39,11 +39,11 @@ - (void)viewDidLoad {
   [_engine runWithEntrypoint:nil];
 }
 
-- (FlutterViewController*)showFlutter {
+- (FlutterViewController*)showFlutter:(void (^)(void))showCompletion {
   FlutterViewController* flutterVC = [[FlutterViewController alloc] initWithEngine:_engine
                                                                            nibName:nil
                                                                             bundle:nil];
-  [self presentViewController:flutterVC animated:NO completion:nil];
+  [self presentViewController:flutterVC animated:NO completion:showCompletion];
   return flutterVC;
 }
 

testing/scenario_app/ios/Scenarios/ScenariosTests/AppLifecycleTests.m

@@ -64,29 +64,34 @@ - (void)testDismissedFlutterViewControllerNotRespondingToApplicationLifecycle {
     [[XCAppLifecycleTestExpectation alloc] initForLifecycle:@"AppLifecycleState.resumed"
                                                     forStep:@"showing a FlutterViewController"]
   ]];
+  
+  [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
+    if (lifecycleExpectations.count == 0) {
+      XCTFail(@"Unexpected lifecycle transition: %@", message);
+      return;
+    }
+    XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
+    if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
+      XCTFail(@"Expected lifecycle %@ but instead received %@",
+              [nextExpectation expectedLifecycle], message);
+      return;
+    }
+
+    [nextExpectation fulfill];
+    [lifecycleExpectations removeObjectAtIndex:0];
+  }];
 
   FlutterViewController* flutterVC;
   @autoreleasepool {
     // Holding onto this FlutterViewController is consequential here. Since a released
     // FlutterViewController wouldn't keep listening to the application lifecycle events and produce
     // false positives for the application lifecycle tests further below.
-    flutterVC = [rootVC showFlutter];
-    NSLog(@"FlutterViewController instance %@ created", flutterVC);
-    [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
-      if (lifecycleExpectations.count == 0) {
-        XCTFail(@"Unexpected lifecycle transition: %@", message);
-        return;
-      }
-      XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
-      if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
-        XCTFail(@"Expected lifecycle %@ but instead received %@",
-                [nextExpectation expectedLifecycle], message);
-        return;
-      }
-
-      [nextExpectation fulfill];
-      [lifecycleExpectations removeObjectAtIndex:0];
+    XCTestExpectation* vcShown = [self expectationWithDescription:@"present"];
+    flutterVC = [rootVC showFlutter:^{
+      [vcShown fulfill];
     }];
+    [self waitForExpectationsWithTimeout:5.0 handler:nil];
+    NSLog(@"FlutterViewController instance %@ created", flutterVC);
 
     // The expectations list isn't dequeued by the message handler yet.
     [self waitForExpectations:lifecycleExpectations timeout:5 enforceOrder:YES];
@@ -147,7 +152,11 @@ - (void)testDismissedFlutterViewControllerNotRespondingToApplicationLifecycle {
   ]];
 
   @autoreleasepool {
-    flutterVC = [rootVC showFlutter];
+    XCTestExpectation* vcShown = [self expectationWithDescription:@"present"];
+    flutterVC = [rootVC showFlutter:^{
+      [vcShown fulfill];
+    }];
+    [self waitForExpectationsWithTimeout:5.0 handler:nil];
     NSLog(@"FlutterViewController instance %@ created", flutterVC);
     [self waitForExpectations:lifecycleExpectations timeout:5 enforceOrder:YES];
 
@@ -199,26 +208,31 @@ - (void)testVisibleFlutterViewControllerRespondsToApplicationLifecycle {
     [[XCAppLifecycleTestExpectation alloc] initForLifecycle:@"AppLifecycleState.resumed"
                                                     forStep:@"showing a FlutterViewController"]
   ]];
+  
+  [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
+    if (lifecycleExpectations.count == 0) {
+      XCTFail(@"Unexpected lifecycle transition: %@", message);
+      return;
+    }
+    XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
+    if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
+      XCTFail(@"Expected lifecycle %@ but instead received %@",
+              [nextExpectation expectedLifecycle], message);
+      return;
+    }
+
+    [nextExpectation fulfill];
+    [lifecycleExpectations removeObjectAtIndex:0];
+  }];
 
   FlutterViewController* flutterVC;
   @autoreleasepool {
-    flutterVC = [rootVC showFlutter];
-    NSLog(@"FlutterViewController instance %@ created", flutterVC);
-    [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
-      if (lifecycleExpectations.count == 0) {
-        XCTFail(@"Unexpected lifecycle transition: %@", message);
-        return;
-      }
-      XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
-      if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
-        XCTFail(@"Expected lifecycle %@ but instead received %@",
-                [nextExpectation expectedLifecycle], message);
-        return;
-      }
-
-      [nextExpectation fulfill];
-      [lifecycleExpectations removeObjectAtIndex:0];
+    XCTestExpectation* vcShown = [self expectationWithDescription:@"present"];
+    flutterVC = [rootVC showFlutter:^{
+      [vcShown fulfill];
     }];
+    [self waitForExpectationsWithTimeout:5.0 handler:nil];
+    NSLog(@"FlutterViewController instance %@ created", flutterVC);
 
     [self waitForExpectations:lifecycleExpectations timeout:5];
 
@@ -304,27 +318,33 @@ - (void)testFlutterViewControllerDetachingSendsApplicationLifecycle {
     [[XCAppLifecycleTestExpectation alloc] initForLifecycle:@"AppLifecycleState.resumed"
                                                     forStep:@"showing a FlutterViewController"]
   ]];
+  
+  [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
+    if (lifecycleExpectations.count == 0) {
+      XCTFail(@"Unexpected lifecycle transition: %@", message);
+      return;
+    }
+    XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
+    if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
+      XCTFail(@"Expected lifecycle %@ but instead received %@",
+              [nextExpectation expectedLifecycle], message);
+      return;
+    }
+
+    [nextExpectation fulfill];
+    [lifecycleExpectations removeObjectAtIndex:0];
+  }];
+  
   // At the end of Flutter VC, we want to make sure it deallocs and sends detached signal.
   // Using autoreleasepool will guarantee that.
   FlutterViewController* flutterVC;
   @autoreleasepool {
-    flutterVC = [rootVC showFlutter];
-    NSLog(@"FlutterViewController instance %@ created", flutterVC);
-    [engine.lifecycleChannel setMessageHandler:^(id message, FlutterReply callback) {
-      if (lifecycleExpectations.count == 0) {
-        XCTFail(@"Unexpected lifecycle transition: %@", message);
-        return;
-      }
-      XCAppLifecycleTestExpectation* nextExpectation = [lifecycleExpectations objectAtIndex:0];
-      if (![[nextExpectation expectedLifecycle] isEqualToString:message]) {
-        XCTFail(@"Expected lifecycle %@ but instead received %@",
-                [nextExpectation expectedLifecycle], message);
-        return;
-      }
-
-      [nextExpectation fulfill];
-      [lifecycleExpectations removeObjectAtIndex:0];
+    XCTestExpectation* vcShown = [self expectationWithDescription:@"present"];
+    flutterVC = [rootVC showFlutter:^{
+      [vcShown fulfill];
     }];
+    [self waitForExpectationsWithTimeout:5.0 handler:nil];
+    NSLog(@"FlutterViewController instance %@ created", flutterVC);
 
     [self waitForExpectations:lifecycleExpectations timeout:5];