test(scrollview): cover iOS anchor after content shrink

Author: aryan1306

packages/react-native/React/Tests/Mounting/RCTScrollViewComponentViewTests.mm

@@ -25,13 +25,65 @@
 
 @interface RCTScrollViewComponentView (Tests)
 - (void)_keyboardWillChangeFrame:(NSNotification *)notification;
+- (void)_prepareForMaintainVisibleScrollPosition;
+- (void)_adjustForMaintainVisibleContentPosition;
 @end
 
 @interface RCTScrollViewComponentViewTests : XCTestCase
 @end
 
 @implementation RCTScrollViewComponentViewTests
 
+- (void)testMaintainVisibleContentPositionAfterVerticalShrink
+{
+  RCTScrollViewComponentView *view = [[RCTScrollViewComponentView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
+  auto props = std::make_shared<ScrollViewProps>();
+  props->maintainVisibleContentPosition = facebook::react::ScrollViewMaintainVisibleContentPosition{};
+  [view updateProps:props oldProps:ScrollViewShadowNode::defaultSharedProps()];
+
+  RCTViewComponentView *contentView = [[RCTViewComponentView alloc] initWithFrame:CGRectMake(0, 0, 100, 1000)];
+  [view mountChildComponentView:contentView index:0];
+  UIView *anchor = [[UIView alloc] initWithFrame:CGRectMake(0, 800, 100, 40)];
+  anchor.tag = 42;
+  [contentView addSubview:anchor];
+
+  view.scrollView.contentSize = CGSizeMake(100, 1000);
+  view.scrollView.contentOffset = CGPointMake(0, 800);
+  [view _prepareForMaintainVisibleScrollPosition];
+
+  anchor.frame = CGRectMake(0, 300, 100, 40);
+  view.scrollView.contentSize = CGSizeMake(100, 400);
+  view.scrollView.contentOffset = CGPointZero;
+  [view _adjustForMaintainVisibleContentPosition];
+
+  XCTAssertEqualWithAccuracy(view.scrollView.contentOffset.y, 300, 0.5);
+}
+
+- (void)testMaintainVisibleContentPositionAfterHorizontalShrink
+{
+  RCTScrollViewComponentView *view = [[RCTScrollViewComponentView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
+  auto props = std::make_shared<ScrollViewProps>();
+  props->maintainVisibleContentPosition = facebook::react::ScrollViewMaintainVisibleContentPosition{};
+  [view updateProps:props oldProps:ScrollViewShadowNode::defaultSharedProps()];
+
+  RCTViewComponentView *contentView = [[RCTViewComponentView alloc] initWithFrame:CGRectMake(0, 0, 1000, 100)];
+  [view mountChildComponentView:contentView index:0];
+  UIView *anchor = [[UIView alloc] initWithFrame:CGRectMake(800, 0, 40, 100)];
+  anchor.tag = 42;
+  [contentView addSubview:anchor];
+
+  view.scrollView.contentSize = CGSizeMake(1000, 100);
+  view.scrollView.contentOffset = CGPointMake(800, 0);
+  [view _prepareForMaintainVisibleScrollPosition];
+
+  anchor.frame = CGRectMake(300, 0, 40, 100);
+  view.scrollView.contentSize = CGSizeMake(400, 100);
+  view.scrollView.contentOffset = CGPointZero;
+  [view _adjustForMaintainVisibleContentPosition];
+
+  XCTAssertEqualWithAccuracy(view.scrollView.contentOffset.x, 300, 0.5);
+}
+
 - (void)testAutomaticallyAdjustKeyboardInsetsAcrossRecycling
 {
   RCTScrollViewComponentView *view = [[RCTScrollViewComponentView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];

packages/rn-tester/RNTesterPods.xcodeproj/project.pbxproj

@@ -18,6 +18,7 @@
 		79B29C2E2E607A99007612A5 /* SceneDelegate.mm in Sources */ = {isa = PBXBuildFile; fileRef = 79B29C2D2E607A99007612A5 /* SceneDelegate.mm */; };
 		8145AE06241172D900A3F8DA /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 8145AE05241172D900A3F8DA /* LaunchScreen.storyboard */; };
 		832F45BB2A8A6E1F0097B4E6 /* SwiftTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 832F45BA2A8A6E1F0097B4E6 /* SwiftTest.swift */; };
+		86178A1D4F95F48D0DC933E2 /* RCTScrollViewComponentViewTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 6250ED894CD7F3B5A761FE63 /* RCTScrollViewComponentViewTests.mm */; };
 		A975CA6C2C05EADF0043F72A /* RCTNetworkTaskTests.m in Sources */ = {isa = PBXBuildFile; fileRef = A975CA6B2C05EADE0043F72A /* RCTNetworkTaskTests.m */; };
 		C175B6D9ED9336FB66637943 /* libPods-RNTester.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 4C706D402EE4AF9BE838CBA9 /* libPods-RNTester.a */; };
 		CD10C7A5290BD4EB0033E1ED /* RCTEventEmitterTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CD10C7A4290BD4EB0033E1ED /* RCTEventEmitterTests.m */; };
@@ -93,6 +94,7 @@
 		4C706D402EE4AF9BE838CBA9 /* libPods-RNTester.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-RNTester.a"; sourceTree = BUILT_PRODUCTS_DIR; };
 		51BC9297B6C3163C14532020 /* Pods-RNTester.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RNTester.release.xcconfig"; path = "Target Support Files/Pods-RNTester/Pods-RNTester.release.xcconfig"; sourceTree = "<group>"; };
 		5C60EB1B226440DB0018C04F /* AppDelegate.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = AppDelegate.mm; path = RNTester/AppDelegate.mm; sourceTree = "<group>"; };
+		6250ED894CD7F3B5A761FE63 /* RCTScrollViewComponentViewTests.mm */ = {isa = PBXFileReference; includeInIndex = 1; name = RCTScrollViewComponentViewTests.mm; path = "../react-native/React/Tests/Mounting/RCTScrollViewComponentViewTests.mm"; sourceTree = "<group>"; };
 		79B29C2C2E607A99007612A5 /* SceneDelegate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = SceneDelegate.h; path = RNTester/SceneDelegate.h; sourceTree = "<group>"; };
 		79B29C2D2E607A99007612A5 /* SceneDelegate.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = SceneDelegate.mm; path = RNTester/SceneDelegate.mm; sourceTree = "<group>"; };
 		8145AE05241172D900A3F8DA /* LaunchScreen.storyboard */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.storyboard; name = LaunchScreen.storyboard; path = RNTester/LaunchScreen.storyboard; sourceTree = "<group>"; };
@@ -267,6 +269,14 @@
 			name = Frameworks;
 			sourceTree = "<group>";
 		};
+		46F51AC598EF6515ADF3A7D9 /* LocalScrollViewTests */ = {
+			isa = PBXGroup;
+			children = (
+				6250ED894CD7F3B5A761FE63 /* RCTScrollViewComponentViewTests.mm */,
+			);
+			name = LocalScrollViewTests;
+			sourceTree = "<group>";
+		};
 		680759612239798500290469 /* Fabric */ = {
 			isa = PBXGroup;
 			children = (
@@ -284,6 +294,7 @@
 				83CBBA001A601CBA00E9B192 /* Products */,
 				2DE7E7D81FB2A4F3009E225D /* Frameworks */,
 				E23BD6487B06BD71F1A86914 /* Pods */,
+				46F51AC598EF6515ADF3A7D9 /* LocalScrollViewTests */,
 			);
 			indentWidth = 2;
 			sourceTree = "<group>";
@@ -774,6 +785,7 @@
 				E7DB20EB22B2BAA6005AC45F /* RCTConvert_YGValueTests.m in Sources */,
 				E7DB20E922B2BAA6005AC45F /* RCTComponentPropsTests.m in Sources */,
 				E7DB20D822B2BAA6005AC45F /* RCTJSONTests.m in Sources */,
+				86178A1D4F95F48D0DC933E2 /* RCTScrollViewComponentViewTests.mm in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};