// Copyright 2026 The Chromium Authors // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #import #import "base/apple/foundation_util.h" #import "base/strings/stringprintf.h" #import "base/strings/sys_string_conversions.h" #import "ios/web/public/test/javascript_test.h" #import "ios/web/public/test/js_test_util.h" #import "testing/gtest/include/gtest/gtest.h" namespace { class PageStabilityJavascriptTest : public web::JavascriptTest { protected: void SetUp() override { web::JavascriptTest::SetUp(); AddGCrWebScript(); AddUserScript(@"page_stability"); ASSERT_TRUE(LoadHtml(@"")); } }; TEST_F(PageStabilityJavascriptTest, WaitForStability_NoMutations_Resolves) { NSString* script = @R"( return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 100, mutationCap: 5, timeoutMs: 1000, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_TRUE([resultDict[@"settled"] boolValue]); EXPECT_EQ([resultDict[@"mutationCount"] intValue], 0); } TEST_F(PageStabilityJavascriptTest, WaitForStability_PageStabilizes_Resolves) { // Schedule a single mutation and wait for stability in a single block // to prevent scheduling race conditions. NSString* script = @R"( setTimeout(() => { document.body.appendChild(document.createElement('div')); }, 100); return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 300, mutationCap: 5, timeoutMs: 1000, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_TRUE([resultDict[@"settled"] boolValue]); EXPECT_EQ([resultDict[@"mutationCount"] intValue], 1); } TEST_F(PageStabilityJavascriptTest, WaitForStability_PageEventuallyStabilizes_ResolvesToSuccess) { // Schedule recurrent mutations to force the page to be unstable for the // first two windows, but stabilize during the third window. NSString* script = @R"( var count = 0; var interval = setInterval(() => { document.body.appendChild(document.createElement('div')); count++; if (count >= 8) clearInterval(interval); }, 30); return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 100, mutationCap: 2, timeoutMs: 2000, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_TRUE([resultDict[@"settled"] boolValue]); EXPECT_LE([resultDict[@"mutationCount"] intValue], 2); } TEST_F(PageStabilityJavascriptTest, WaitForStability_PageDoesNotStabilize_TimesOut) { // Schedule sustained infinite mutations to force the check to time out. NSString* script = @R"( var logs = []; window.startTime = performance.now(); var startTime = window.startTime; var interval = setInterval(() => { document.body.appendChild(document.createElement('div')); logs.push('interval at ' + (performance.now() - startTime).toFixed(1) + 'ms'); }, 30); var promise = __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 100, mutationCap: 2, timeoutMs: 300, }); promise = promise.then((res) => { clearInterval(interval); res.logs = logs; res.debugLogs = window.debugLogs || []; res.elapsed = performance.now() - startTime; return res; }).catch((err) => { clearInterval(interval); throw err; }); return promise; )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_FALSE([resultDict[@"settled"] boolValue]); EXPECT_TRUE([resultDict[@"timedOut"] boolValue]); } TEST_F(PageStabilityJavascriptTest, WaitForStability_TimeoutLessThanWindow_TimesOut) { // Set timeout smaller than the window duration. It should time out // even if there are no mutations. NSString* script = @R"( return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 200, mutationCap: 5, timeoutMs: 50, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_FALSE([resultDict[@"settled"] boolValue]); EXPECT_TRUE([resultDict[@"timedOut"] boolValue]); } TEST_F(PageStabilityJavascriptTest, WaitForStability_ContinuousSingleMutationWithZeroCap_TimesOut) { // Schedule a mutation every 80ms. With a window duration of 100ms and cap of // 0, the page will never be stable, so it should time out. NSString* script = @R"( var interval = setInterval(() => { document.body.appendChild(document.createElement('div')); }, 80); var promise = __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 100, mutationCap: 0, timeoutMs: 300, }); promise.then(() => { clearInterval(interval); }) .catch(() => { clearInterval(interval); }); return promise; )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_FALSE([resultDict[@"settled"] boolValue]); EXPECT_TRUE([resultDict[@"timedOut"] boolValue]); } TEST_F(PageStabilityJavascriptTest, WaitForStability_Cancel_ResolvesToUnsettled) { NSString* script = @R"( var promise = __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForStability')({ windowDurationMs: 500, mutationCap: 2, timeoutMs: 2000, }); __gCrWeb.getRegisteredApi('page_stability') .getFunction('cancelWaitForStability')(); return promise; )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_FALSE([resultDict[@"settled"] boolValue]); EXPECT_FALSE([resultDict[@"timedOut"] boolValue]); } // Test that WaitForLcp resolves to false when the timeout is reached. TEST_F(PageStabilityJavascriptTest, WaitForLcp_Timeout_ResolvesToFalse) { NSString* script = @R"( return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForLcp')({ timeoutMs: 10, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_NE(nil, resultDict[@"lcpReceived"]); EXPECT_FALSE([resultDict[@"lcpReceived"] boolValue]); } // Test that WaitForLcp resolves to false when cancelWaitForLcp is called. TEST_F(PageStabilityJavascriptTest, WaitForLcp_Cancel_ResolvesToFalse) { NSString* script = @R"( const promise = __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForLcp')({ timeoutMs: 5000, }); setTimeout(() => { __gCrWeb.getRegisteredApi('page_stability') .getFunction('cancelWaitForLcp')(); }, 100); return promise; )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_NE(nil, resultDict[@"lcpReceived"]); EXPECT_FALSE([resultDict[@"lcpReceived"] boolValue]); } // Test that WaitForLcp resolves to true if Largest Contentful Paint already // was recorded. TEST_F(PageStabilityJavascriptTest, WaitForLcp_Success_LcpAlreadyExists) { NSString* script = @R"( window.PerformanceObserver = function() {}; window.PerformanceObserver.supportedEntryTypes = ['largest-contentful-paint']; performance.getEntriesByType = (type) => { if (type === 'largest-contentful-paint') { return [{ entryType: 'largest-contentful-paint' }]; } }; return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForLcp')({ timeoutMs: 1000, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_NE(nil, resultDict[@"lcpReceived"]); EXPECT_TRUE([resultDict[@"lcpReceived"] boolValue]); } // Test that WaitForLcp resolves to true if Largest Contentful Paint triggers // while waiting. TEST_F(PageStabilityJavascriptTest, WaitForLcp_Success_LcpFiresLater) { NSString* script = @R"( window.PerformanceObserver = function(callback) { this.observe = () => { callback({ getEntries: () => [{ entryType: 'largest-contentful-paint' }] }); }; this.disconnect = () => {}; }; window.PerformanceObserver.supportedEntryTypes = ['largest-contentful-paint']; return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForLcp')({ timeoutMs: 2000, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_NE(nil, resultDict[@"lcpReceived"]); EXPECT_TRUE([resultDict[@"lcpReceived"] boolValue]); } // Test that WaitForLcp resolves to false when PerformanceObserver does not // support the LCP entry type. TEST_F(PageStabilityJavascriptTest, WaitForLcp_LcpEntryNotSupported) { NSString* script = @R"( window.PerformanceObserver = function() {}; window.PerformanceObserver.supportedEntryTypes = ['measure']; return __gCrWeb.getRegisteredApi('page_stability') .getFunction('waitForLcp')({ timeoutMs: 100, }); )"; id result = web::test::ExecuteAsyncJavaScript(web_view(), script, nil); NSDictionary* resultDict = base::apple::ObjCCast(result); ASSERT_TRUE(resultDict); EXPECT_NE(nil, resultDict[@"lcpReceived"]); EXPECT_FALSE([resultDict[@"lcpReceived"] boolValue]); } } // namespace