feat: Refactor snapshotting mechanism

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;

WebDriverAgentLib/Categories/FBXCElementSnapshotWrapper+Helpers.h

@@ -58,9 +58,14 @@ 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 timeout The maximum time is flota seconds to wait until XCTest/Accessbility framework
+ returns the value of the requested attribute
+ @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
+                         timeout:(NSTimeInterval)timeout
+                           error:(NSError **)error;
 
 /**
  Method used to determine whether given element matches receiver by comparing it's parameters except frame.

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 VisibleFrameFetchTimeout 0.3
+
 inline static BOOL isSnapshotTypeAmongstGivenTypes(id<FBXCElementSnapshot> snapshot,
                                                    NSArray<NSNumber *> *types);
 
@@ -65,10 +69,38 @@ - (NSString *)fb_description
 }
 
 - (id)fb_attributeValue:(NSString *)attribute
-{
-  NSDictionary *result = [FBXCAXClientProxy.sharedClient attributesForElement:[self accessibilityElement]
-                                                                   attributes:@[attribute]];
-  return result[attribute];
+                timeout:(NSTimeInterval)timeout
+                  error:(NSError **)error
+{
+  id<XCTestManager_ManagerInterface> proxy = [FBXCTestDaemonsProxy testRunnerProxy];
+  dispatch_semaphore_t sem = dispatch_semaphore_create(0);
+  __block NSDictionary *result = nil;
+  __block NSError *blockError;
+  [proxy _XCT_fetchAttributes:@[attribute]
+                   forElement:[self accessibilityElement]
+                        reply:^(NSDictionary *innerResult, NSError *innerError) {
+    if (nil == innerError) {
+      result = innerResult;
+    } else {
+      blockError = innerError;
+    }
+    dispatch_semaphore_signal(sem);
+  }];
+  if (0 != dispatch_semaphore_wait(sem, dispatch_time(DISPATCH_TIME_NOW, (int64_t)(timeout * NSEC_PER_SEC)))) {
+    NSString *timeoutMsg = [NSString stringWithFormat:@"Cannot fetch %@ attribute of '%@' within %@s timeout",
+                            attribute, self.fb_description, @(timeout)];
+    [[[FBErrorBuilder builder]
+      withDescription:timeoutMsg]
+     buildError:error];
+    return nil;
+  }
+  if (nil != result) {
+    return [result objectForKey:attribute];
+  }
+  if (error) {
+    *error = blockError;
+  }
+  return nil;
 }
 
 inline static BOOL areValuesEqual(id value1, id value2);
@@ -146,8 +178,10 @@ - (CGRect)fb_visibleFrameWithFallback
   if (!CGRectIsEmpty(thisVisibleFrame)) {
     return thisVisibleFrame;
   }
-
-  NSDictionary *visibleFrameDict = (NSDictionary*)[self fb_attributeValue:@"XC_kAXXCAttributeVisibleFrame"];
+
+  NSDictionary *visibleFrameDict = [self fb_attributeValue:FB_XCAXAVisibleFrameAttributeName
+                                                   timeout:VisibleFrameFetchTimeout
+                                                     error:nil];
   if (visibleFrameDict == nil) {
     return thisVisibleFrame;
   }

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

@@ -14,12 +14,13 @@
 #import "XCUIElement+FBUtilities.h"
 #import "FBXCElementSnapshotWrapper+Helpers.h"
 
+#define AX_FETCH_TIMEOUT 0.3
+
 @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 +34,18 @@ - (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
+                                             timeout:AX_FETCH_TIMEOUT
+                                               error:&error];
+  if (nil != attributeValue) {
+    return [attributeValue boolValue];
+  }
+
+  NSLog(@"Cannot determine '%@' accessibility 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];
 }