In Bug 227925 we discovered that two API tests related to Extensible SSO failed consistently on the iOS simulator, and was flaky on some versions of macOS. I had added a flag to indicate that WKWebView's "decidePolicyForSOAuthorizationLoadWithCurrentPolicy" delegate had been called, but found that this did not consistently happen. This might be because the test involves loading sub-frames of live websites, which might not always resolve and load in the 0.5 second timeout specified in the test. ===================================== TestWebKitAPI.SOAuthorizationSubFrame.SOAuthorizationLoadPolicyIgnore /Volumes/Data/worker/ios-simulator-14-release/build/Tools/TestWebKitAPI/Tests/WebKitCocoa/TestSOAuthorization.mm:2586 Value of: policyForAppSSOPerformed Actual: true Expected: false TestWebKitAPI.SOAuthorizationSubFrame.SOAuthorizationLoadPolicyIgnoreAsync /Volumes/Data/worker/ios-simulator-14-release/build/Tools/TestWebKitAPI/Tests/WebKitCocoa/TestSOAuthorization.mm:2643 Value of: policyForAppSSOPerformed Actual: true Expected: false ===================================== We should investigate this further and make the tests more deterministic to avoid this problem.