feat: Refactor snapshotting mechanism (#970)

BREAKING CHANGE: snapshotTimeout and customSnapshotTimeout settings have been removed as a result of the custom snapshotting logic removal

Author: mykola-mokhnach

PrivateHeaders/XCTest/XCTestManager_ManagerInterface-Protocol.h

@@ -27,6 +27,7 @@
 - (void)_XCT_requestElementAtPoint:(CGPoint)arg1 reply:(void (^)(id/*XCAccessibilityElement*/, NSError *))arg2;
 - (void)_XCT_fetchParameterizedAttributeForElement:(id/*XCAccessibilityElement*/)arg1 attributes:(NSNumber *)arg2 parameter:(id)arg3 reply:(void (^)(id, NSError *))arg4;
 - (void)_XCT_setAttribute:(NSNumber *)arg1 value:(id)arg2 element:(id/*XCAccessibilityElement*/)arg3 reply:(void (^)(BOOL, NSError *))arg4;
+- (void)_XCT_fetchAttributes:(id)attributes forElement:(id)element reply:(void (^)(NSDictionary *, NSError *))reply;
 - (void)_XCT_fetchAttributesForElement:(id/*XCAccessibilityElement*/)arg1 attributes:(NSArray *)arg2 reply:(void (^)(NSDictionary *, NSError *))arg3;
 - (void)_XCT_terminateApplicationWithBundleID:(NSString *)arg1 completion:(void (^)(NSError *))arg2;
 - (void)_XCT_performAccessibilityAction:(int)arg1 onElement:(id/*XCAccessibilityElement*/)arg2 withValue:(id)arg3 reply:(void (^)(NSError *))arg4;

WebDriverAgent.xcodeproj/project.pbxproj

@@ -451,6 +451,10 @@
 		71A7EAFA1E224648001DA4F2 /* FBClassChainQueryParser.m in Sources */ = {isa = PBXBuildFile; fileRef = 71A7EAF81E224648001DA4F2 /* FBClassChainQueryParser.m */; };
 		71A7EAFC1E229302001DA4F2 /* FBClassChainTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 71A7EAFB1E229302001DA4F2 /* FBClassChainTests.m */; };
 		71ACF5B8242F2FDC00F0AAD4 /* FBSafariAlertTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 71ACF5B7242F2FDC00F0AAD4 /* FBSafariAlertTests.m */; };
+		71AE3CF72D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h in Headers */ = {isa = PBXBuildFile; fileRef = 71AE3CF52D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h */; };
+		71AE3CF82D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m in Sources */ = {isa = PBXBuildFile; fileRef = 71AE3CF62D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m */; };
+		71AE3CF92D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h in Headers */ = {isa = PBXBuildFile; fileRef = 71AE3CF52D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h */; };
+		71AE3CFA2D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m in Sources */ = {isa = PBXBuildFile; fileRef = 71AE3CF62D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m */; };
 		71B155DA23070ECF00646AFB /* FBHTTPStatusCodes.h in Headers */ = {isa = PBXBuildFile; fileRef = 71B155D923070ECF00646AFB /* FBHTTPStatusCodes.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		71B155DC230711E900646AFB /* FBCommandStatus.m in Sources */ = {isa = PBXBuildFile; fileRef = 71B155DB230711E900646AFB /* FBCommandStatus.m */; };
 		71B155DF23080CA600646AFB /* FBProtocolHelpers.h in Headers */ = {isa = PBXBuildFile; fileRef = 71B155DD23080CA600646AFB /* FBProtocolHelpers.h */; };
@@ -1050,6 +1054,8 @@
 		71A7EAF81E224648001DA4F2 /* FBClassChainQueryParser.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FBClassChainQueryParser.m; sourceTree = "<group>"; };
 		71A7EAFB1E229302001DA4F2 /* FBClassChainTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FBClassChainTests.m; sourceTree = "<group>"; };
 		71ACF5B7242F2FDC00F0AAD4 /* FBSafariAlertTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = FBSafariAlertTests.m; sourceTree = "<group>"; };
+		71AE3CF52D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "XCUIElement+FBVisibleFrame.h"; sourceTree = "<group>"; };
+		71AE3CF62D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = "XCUIElement+FBVisibleFrame.m"; sourceTree = "<group>"; };
 		71B155D923070ECF00646AFB /* FBHTTPStatusCodes.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FBHTTPStatusCodes.h; sourceTree = "<group>"; };
 		71B155DB230711E900646AFB /* FBCommandStatus.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = FBCommandStatus.m; sourceTree = "<group>"; };
 		71B155DD23080CA600646AFB /* FBProtocolHelpers.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FBProtocolHelpers.h; sourceTree = "<group>"; };
@@ -1781,6 +1787,8 @@
 				71B49EC61ED1A58100D51AD6 /* XCUIElement+FBUID.m */,
 				EEE3763F1D59F81400ED88DD /* XCUIElement+FBUtilities.h */,
 				EEE376401D59F81400ED88DD /* XCUIElement+FBUtilities.m */,
+				71AE3CF52D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h */,
+				71AE3CF62D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m */,
 				EEE376471D59FAE900ED88DD /* XCUIElement+FBWebDriverAttributes.h */,
 				EEE376481D59FAE900ED88DD /* XCUIElement+FBWebDriverAttributes.m */,
 				641EE7042240CDCF00173FCB /* XCUIElement+FBTVFocuse.h */,
@@ -2399,6 +2407,7 @@
 				641EE6A42240C5CA00173FCB /* FBCommandHandler.h in Headers */,
 				641EE6A52240C5CA00173FCB /* FBSessionCommands.h in Headers */,
 				641EE70C2240CE2D00173FCB /* FBTVNavigationTracker.h in Headers */,
+				71AE3CF72D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h in Headers */,
 				641EE6A62240C5CA00173FCB /* FBImageProcessor.h in Headers */,
 				641EE6A72240C5CA00173FCB /* FBSession-Private.h in Headers */,
 				641EE6A82240C5CA00173FCB /* NSString+FBXMLSafeString.h in Headers */,
@@ -2585,6 +2594,7 @@
 				714EAA0D2673FDFE005C5B47 /* FBCapabilities.h in Headers */,
 				EE35AD5C1E3B77D600A02D78 /* XCTNSPredicateExpectation.h in Headers */,
 				EE35AD521E3B77D600A02D78 /* XCTestObservationCenter.h in Headers */,
+				71AE3CF92D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.h in Headers */,
 				EE35AD5B1E3B77D600A02D78 /* XCTNSNotificationExpectation.h in Headers */,
 				E444DC97249131D40060D7EB /* HTTPServer.h in Headers */,
 				E444DCAE24913C220060D7EB /* HTTPResponseProxy.h in Headers */,
@@ -3160,6 +3170,7 @@
 				641EE60E2240C5CA00173FCB /* XCUIElement+FBTyping.m in Sources */,
 				641EE60F2240C5CA00173FCB /* XCUIElement+FBAccessibility.m in Sources */,
 				641EE6102240C5CA00173FCB /* FBImageUtils.m in Sources */,
+				71AE3CF82D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m in Sources */,
 				641EE6112240C5CA00173FCB /* FBSession.m in Sources */,
 				641EE6122240C5CA00173FCB /* FBFindElementCommands.m in Sources */,
 				71A5C67629A4F39600421C37 /* XCTIssue+FBPatcher.m in Sources */,
@@ -3232,6 +3243,7 @@
 				713AE576243A53BE0000D657 /* FBW3CActionsHelpers.m in Sources */,
 				71B155E123080CA600646AFB /* FBProtocolHelpers.m in Sources */,
 				EE158AB11CBD456F00A3E3F0 /* XCUIElement+FBIsVisible.m in Sources */,
+				71AE3CFA2D38EE8E0039FC36 /* XCUIElement+FBVisibleFrame.m in Sources */,
 				EEBBD48C1D47746D00656A81 /* XCUIElement+FBFind.m in Sources */,
 				EE158ADD1CBD456F00A3E3F0 /* FBResponsePayload.m in Sources */,
 				E444DCB524913C220060D7EB /* RouteRequest.m in Sources */,

WebDriverAgentLib/Categories/FBXCElementSnapshotWrapper+Helpers.h

@@ -58,9 +58,11 @@ NS_ASSUME_NONNULL_BEGIN
 
  @param attribute attribute's accessibility identifier. Can be one of
  `XC_kAXXCAttribute`-prefixed attribute names.
- @return value for given accessibility property identifier
+ @param error Error instance in case of a failure
+ @return value for given accessibility property identifier or nil in case of failure
  */
-- (nullable id)fb_attributeValue:(NSString *)attribute;
+- (nullable id)fb_attributeValue:(NSString *)attribute
+                           error:(NSError **)error;
 
 /**
  Method used to determine whether given element matches receiver by comparing it's parameters except frame.
@@ -87,13 +89,6 @@ NS_ASSUME_NONNULL_BEGIN
 /**! Human-readable snapshot description */
 - (NSString *)fb_description;
 
-/**
- Returns the snapshot visibleFrame with a fallback to direct attribute retrieval from FBXCAXClient in case of a snapshot fault (nil visibleFrame)
- 
- @return the snapshot visibleFrame
- */
-- (CGRect)fb_visibleFrameWithFallback;
-
 /**
  Wrapper for Apple's hitpoint, thats resolves few known issues
 

WebDriverAgentLib/Categories/FBXCElementSnapshotWrapper+Helpers.m

@@ -10,16 +10,20 @@
 #import "FBXCElementSnapshotWrapper+Helpers.h"
 
 #import "FBFindElementCommands.h"
+#import "FBErrorBuilder.h"
 #import "FBRunLoopSpinner.h"
 #import "FBLogger.h"
 #import "FBXCElementSnapshot.h"
+#import "FBXCTestDaemonsProxy.h"
 #import "FBXCAXClientProxy.h"
 #import "XCTestDriver.h"
 #import "XCTestPrivateSymbols.h"
 #import "XCUIElement.h"
 #import "XCUIElement+FBWebDriverAttributes.h"
 #import "XCUIHitPointResult.h"
 
+#define ATTRIBUTE_FETCH_WARN_TIME_LIMIT 0.05
+
 inline static BOOL isSnapshotTypeAmongstGivenTypes(id<FBXCElementSnapshot> snapshot,
                                                    NSArray<NSNumber *> *types);
 
@@ -65,10 +69,17 @@ - (NSString *)fb_description
 }
 
 - (id)fb_attributeValue:(NSString *)attribute
+                  error:(NSError **)error
 {
+  NSDate *start = [NSDate date];
   NSDictionary *result = [FBXCAXClientProxy.sharedClient attributesForElement:[self accessibilityElement]
-                                                                   attributes:@[attribute]];
-  return result[attribute];
+                                                                   attributes:@[attribute]
+                                                                        error:error];
+  NSTimeInterval elapsed = ABS([start timeIntervalSinceNow]);
+  if (elapsed > ATTRIBUTE_FETCH_WARN_TIME_LIMIT) {
+    NSLog(@"! Fetching of %@ value for %@ took %@s", attribute, self.fb_description, @(elapsed));
+  }
+  return [result objectForKey:attribute];
 }
 
 inline static BOOL areValuesEqual(id value1, id value2);
@@ -140,29 +151,6 @@ - (BOOL)fb_framelessFuzzyMatchesElement:(id<FBXCElementSnapshot>)snapshot
   return targetCellSnapshot;
 }
 
-- (CGRect)fb_visibleFrameWithFallback
-{
-  CGRect thisVisibleFrame = [self visibleFrame];
-  if (!CGRectIsEmpty(thisVisibleFrame)) {
-    return thisVisibleFrame;
-  }
-  
-  NSDictionary *visibleFrameDict = (NSDictionary*)[self fb_attributeValue:@"XC_kAXXCAttributeVisibleFrame"];
-  if (visibleFrameDict == nil) {
-    return thisVisibleFrame;
-  }
-  
-  id x = [visibleFrameDict objectForKey:@"X"];
-  id y = [visibleFrameDict objectForKey:@"Y"];
-  id height = [visibleFrameDict objectForKey:@"Height"];
-  id width = [visibleFrameDict objectForKey:@"Width"];
-  if (x != nil && y != nil && height != nil && width != nil) {
-    return CGRectMake([x doubleValue], [y doubleValue], [width doubleValue], [height doubleValue]);
-  }
-  
-  return thisVisibleFrame;
-}
-
 - (NSValue *)fb_hitPoint
 {
   NSError *error;

WebDriverAgentLib/Categories/XCUIApplication+FBAlert.m

@@ -52,7 +52,7 @@ - (nullable XCUIElement *)fb_alertElementFromSafariWithScrollView:(XCUIElement *
   // and conatins at least one text view
   __block NSUInteger buttonsCount = 0;
   __block NSUInteger textViewsCount = 0;
-  id<FBXCElementSnapshot> snapshot = candidate.fb_cachedSnapshot ?: candidate.fb_takeSnapshot;
+  id<FBXCElementSnapshot> snapshot = candidate.fb_cachedSnapshot ?: [candidate fb_takeSnapshot:YES];
   [snapshot enumerateDescendantsUsingBlock:^(id<FBXCElementSnapshot> descendant) {
     XCUIElementType curType = descendant.elementType;
     if (curType == XCUIElementTypeButton) {
@@ -73,7 +73,7 @@ - (XCUIElement *)fb_alertElement
   if (nil == alert) {
     return nil;
   }
-  id<FBXCElementSnapshot> alertSnapshot = alert.fb_cachedSnapshot ?: alert.fb_takeSnapshot;
+  id<FBXCElementSnapshot> alertSnapshot = alert.fb_cachedSnapshot ?: [alert fb_takeSnapshot:YES];
 
   if (alertSnapshot.elementType == XCUIElementTypeAlert) {
     return alert;

WebDriverAgentLib/Categories/XCUIApplication+FBHelpers.m

@@ -176,31 +176,15 @@ - (NSDictionary *)fb_tree
 
 - (NSDictionary *)fb_tree:(nullable NSSet<NSString *> *)excludedAttributes
 {
-  // This set includes XCTest-specific internal attribute names,
-  // while the `excludedAttributes` arg contains human-readable ones
-  NSMutableSet* includedAttributeNames = [NSMutableSet setWithArray:FBCustomAttributeNames()];
-  [includedAttributeNames addObjectsFromArray:FBStandardAttributeNames()];
-  if (nil != excludedAttributes) {
-    for (NSString *attr in excludedAttributes) {
-      NSString *mappedName = [customExclusionAttributesMap() objectForKey:attr];
-      if (nil != mappedName) {
-        [includedAttributeNames removeObject:attr];
-      }
-    }
-  }
-  id<FBXCElementSnapshot> snapshot = nil == excludedAttributes
-    ? [self fb_snapshotWithAllAttributesAndMaxDepth:nil]
-    : [self fb_snapshotWithAttributes:[includedAttributeNames allObjects] maxDepth:nil];
+  id<FBXCElementSnapshot> snapshot = [self fb_takeSnapshot:YES];
   return [self.class dictionaryForElement:snapshot
                                 recursive:YES
                        excludedAttributes:excludedAttributes];
 }
 
 - (NSDictionary *)fb_accessibilityTree
 {
-  id<FBXCElementSnapshot> snapshot = self.fb_isResolvedFromCache.boolValue
-    ? self.lastSnapshot
-    : [self fb_snapshotWithAllAttributesAndMaxDepth:nil];
+  id<FBXCElementSnapshot> snapshot = [self fb_takeSnapshot:YES];
   return [self.class accessibilityInfoForElement:snapshot];
 }
 
@@ -445,8 +429,8 @@ - (BOOL)fb_dismissKeyboardWithKeyNames:(nullable NSArray<NSString *> *)keyNames
 
     id extractedElement = extractIssueProperty(issue, @"element");
 
-    id<FBXCElementSnapshot> elementSnapshot = [extractedElement fb_cachedSnapshot] ?: [extractedElement fb_takeSnapshot];
-    NSDictionary *elementAttributes = elementSnapshot 
+    id<FBXCElementSnapshot> elementSnapshot = [extractedElement fb_cachedSnapshot] ?: [extractedElement fb_takeSnapshot:NO];
+    NSDictionary *elementAttributes = elementSnapshot
       ? [self.class dictionaryForElement:elementSnapshot
                                recursive:NO
                       excludedAttributes:customAttributesToExclude]

WebDriverAgentLib/Categories/XCUIElement+FBAccessibility.m

@@ -18,8 +18,7 @@ @implementation XCUIElement (FBAccessibility)
 
 - (BOOL)fb_isAccessibilityElement
 {
-  id<FBXCElementSnapshot> snapshot = [self fb_snapshotWithAttributes:@[FB_XCAXAIsElementAttributeName]
-                                                            maxDepth:@1];
+  id<FBXCElementSnapshot> snapshot = [self fb_takeSnapshot:NO];
   return [FBXCElementSnapshotWrapper ensureWrapped:snapshot].fb_isAccessibilityElement;
 }
 
@@ -33,8 +32,20 @@ - (BOOL)fb_isAccessibilityElement
   if (nil != isAccessibilityElement) {
     return isAccessibilityElement.boolValue;
   }
-  
-  return [(NSNumber *)[self fb_attributeValue:FB_XCAXAIsElementAttributeName] boolValue];
+
+  NSError *error;
+  NSNumber *attributeValue = [self fb_attributeValue:FB_XCAXAIsElementAttributeName
+                                               error:&error];
+  if (nil != attributeValue) {
+    NSMutableDictionary *updatedValue = [NSMutableDictionary dictionaryWithDictionary:self.additionalAttributes ?: @{}];
+    [updatedValue setObject:attributeValue forKey:FB_XCAXAIsElementAttribute];
+    self.snapshot.additionalAttributes = updatedValue.copy;
+    return [attributeValue boolValue];
+  }
+
+  NSLog(@"Cannot determine accessibility of '%@' natively: %@. Defaulting to: %@",
+        self.fb_description, error.description, @(NO));
+  return NO;
 }
 
 @end

WebDriverAgentLib/Categories/XCUIElement+FBCaching.h

@@ -13,9 +13,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface XCUIElement (FBCaching)
 
-/*! This property is set to YES if the given element has been resolved from the cache, so it is safe to use the `lastSnapshot` property */
-@property (nullable, nonatomic) NSNumber *fb_isResolvedFromCache;
-
 @property (nonatomic, readonly) NSString *fb_cacheId;
 
 @end

WebDriverAgentLib/Categories/XCUIElement+FBCaching.m

@@ -18,20 +18,6 @@
 
 @implementation XCUIElement (FBCaching)
 
-static char XCUIELEMENT_IS_RESOLVED_FROM_CACHE_KEY;
-
-@dynamic fb_isResolvedFromCache;
-
-- (void)setFb_isResolvedFromCache:(NSNumber *)isResolvedFromCache
-{
-  objc_setAssociatedObject(self, &XCUIELEMENT_IS_RESOLVED_FROM_CACHE_KEY, isResolvedFromCache, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
-}
-
-- (NSNumber *)fb_isResolvedFromCache
-{
-  return (NSNumber *)objc_getAssociatedObject(self, &XCUIELEMENT_IS_RESOLVED_FROM_CACHE_KEY);
-}
-
 static char XCUIELEMENT_CACHE_ID_KEY;
 
 @dynamic fb_cacheId;
@@ -43,14 +29,7 @@ - (NSString *)fb_cacheId
     return (NSString *)result;
   }
 
-  NSString *uid;
-  if ([self isKindOfClass:XCUIApplication.class]) {
-    uid = self.fb_uid;
-  } else {
-    id<FBXCElementSnapshot> snapshot = self.fb_cachedSnapshot ?: self.fb_takeSnapshot;
-    uid = [FBXCElementSnapshotWrapper wdUIDWithSnapshot:snapshot];
-  }
-
+  NSString *uid = self.fb_uid;
   objc_setAssociatedObject(self, &XCUIELEMENT_CACHE_ID_KEY, uid, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
   return uid;
 }

WebDriverAgentLib/Categories/XCUIElement+FBFind.m

@@ -110,7 +110,7 @@ @implementation XCUIElement (FBFind)
     matchingSnapshots = @[snapshot];
   }
   return [self fb_filterDescendantsWithSnapshots:matchingSnapshots
-                                         selfUID:[FBXCElementSnapshotWrapper wdUIDWithSnapshot:self.lastSnapshot]
+                                         selfUID:self.fb_uid
                                     onlyChildren:NO];
 }