Stop the UI readiness helpers busy-waiting and cascading failures

UITests/KeyboardResizeUITests.swift

@@ -8,19 +8,19 @@ final class KeyboardResizeUITests: XCTestCase {
         let app = XCUIApplication()
         app.launchArguments = ["--ui-testing"]
         app.launch()
-        app.buttons["addHost"].tapWhenReady()
-        app.textFields["hostName"].typeWhenReady("Keyboard resize")
-        app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
-        app.textFields["hostUsername"].typeWhenReady("tester")
-        app.buttons["saveHost"].tapWhenReady()
-        app.buttons["host-Keyboard resize"].tapWhenReady()
+        try app.buttons["addHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Keyboard resize")
+        try app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
+        try app.textFields["hostUsername"].typeWhenReady("tester")
+        try app.buttons["saveHost"].tapWhenReady()
+        try app.buttons["host-Keyboard resize"].tapWhenReady()
         XCTAssertTrue(app.secureTextFields["Password"].waitForExistence(timeout: 10))
         // #35 landed here. A tap delivered while the credential sheet was still animating in
         // was dropped — worse on an iPad, where it is a form sheet that travels further and
         // settles later — and the sheet then stayed up with the connection still `.connecting`,
         // so the button waited for below, which `TerminalScreen` only draws once the phase
         // leaves `.connecting`, never appeared at all. `tapWhenReady` is what stops that.
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         // Through `waitUntil` rather than `waitForExistence` so a failure here keeps a
         // screenshot: it is what would say whether the sheet is still up or the phase never
         // moved. Cancelling resumes the credential continuation with nil and the connection

UITests/TailscaleImportUITests.swift

@@ -118,7 +118,7 @@ final class TailscaleImportUITests: XCTestCase {
 
         let settings = UIDevice.current.userInterfaceIdiom == .pad
             ? app.buttons["workspaceSettings"] : app.buttons["Settings"]
-        settings.tapWhenReady()
+        try settings.tapWhenReady()
         XCTAssertTrue(app.staticTexts["Terminal font preview"].waitForExistence(timeout: 5))
         app.navigationBars["Settings"].buttons["Done"].tap()
         XCTAssertTrue(app.buttons["importTailscaleHosts"].waitForExistence(timeout: 5))
@@ -179,7 +179,9 @@ final class TailscaleImportUITests: XCTestCase {
             let deadline = ContinuousClock.now.advanced(by: .seconds(3))
             while ContinuousClock.now < deadline {
                 if element.isHittable { return }
-                _ = element.waitForExistence(timeout: 0.2)
+                // Sleeping rather than `waitForExistence`, which returns instantly once the
+                // element exists and so throttles nothing. See `waitUntilHittable`.
+                Thread.sleep(forTimeInterval: 0.05)
             }
             app.swipeUp()
         }

UITests/UITestInteraction.swift

@@ -17,20 +17,27 @@ extension XCUIElement {
     /// The timeout is patience, not a deadline anything has to meet: reaching it means the test
     /// was going to fail regardless, and twenty seconds is not long on a CI runner that has been
     /// building for half an hour and is on its second simulator.
+    ///
+    /// Throws rather than only recording a failure. `continueAfterFailure` is true by default, so
+    /// a helper that failed and returned would let the caller carry on: `typeWhenReady` would
+    /// then type into nothing and raise a second, unrelated "no keyboard focus" error on top of
+    /// the real one, and every later helper in the test would spend its own twenty seconds
+    /// before doing the same — three times over, now that CI retries. Stopping at the first
+    /// unmet precondition keeps the report about the thing that actually went wrong.
     @MainActor
-    func tapWhenReady(timeout: TimeInterval = 20, file: StaticString = #filePath, line: UInt = #line) {
+    func tapWhenReady(timeout: TimeInterval = 20, file: StaticString = #filePath, line: UInt = #line) throws {
         guard waitUntilHittable(timeout: timeout) else {
             XCTFail("\(self) never became hittable", file: file, line: line)
-            return
+            throw UITestInteractionError.neverBecameHittable(String(describing: self))
         }
         tap()
     }
 
     /// Taps and types in one step, which is the shape every form in these tests uses.
     @MainActor
     func typeWhenReady(_ text: String, timeout: TimeInterval = 20,
-                       file: StaticString = #filePath, line: UInt = #line) {
-        tapWhenReady(timeout: timeout, file: file, line: line)
+                       file: StaticString = #filePath, line: UInt = #line) throws {
+        try tapWhenReady(timeout: timeout, file: file, line: line)
         typeText(text)
     }
 
@@ -43,8 +50,23 @@ extension XCUIElement {
         let deadline = Date().addingTimeInterval(timeout)
         while Date() < deadline {
             if exists, isHittable { return true }
-            _ = waitForExistence(timeout: 0.1)
+            // An explicit sleep, not `waitForExistence(timeout:)`. That returns immediately when
+            // the element already exists, which is exactly the case here — present but not yet
+            // touchable — so using it as the throttle spins on back-to-back accessibility
+            // snapshots for the whole timeout. Querying the app that hard is a poor way to wait
+            // for it to settle.
+            Thread.sleep(forTimeInterval: 0.05)
         }
         return exists && isHittable
     }
 }
+
+enum UITestInteractionError: Error, CustomStringConvertible {
+    case neverBecameHittable(String)
+
+    var description: String {
+        switch self {
+        case let .neverBecameHittable(element): return "\(element) never became hittable"
+        }
+    }
+}

UITests/iOSSHUITests.swift

@@ -6,14 +6,14 @@ final class iOSSHUITests: XCTestCase {
         let app = XCUIApplication()
         app.launchArguments = ["--ui-testing"]
         app.launch()
-        app.buttons["addFirstHost"].tapWhenReady()
-        app.textFields["hostName"].typeWhenReady("Japanese input")
-        app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
-        app.textFields["hostUsername"].typeWhenReady("tester")
-        app.buttons["saveHost"].tapWhenReady()
-        app.buttons["host-Japanese input"].tapWhenReady()
+        try app.buttons["addFirstHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Japanese input")
+        try app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
+        try app.textFields["hostUsername"].typeWhenReady("tester")
+        try app.buttons["saveHost"].tapWhenReady()
+        try app.buttons["host-Japanese input"].tapWhenReady()
         XCTAssertTrue(app.secureTextFields["Password"].waitForExistence(timeout: 10))
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         XCTAssertTrue(app.buttons["Reconnect"].waitForExistence(timeout: 5))
         let terminal = app.descendants(matching: .any).matching(identifier: "terminal").firstMatch
         terminal.tap()
@@ -70,14 +70,14 @@ final class iOSSHUITests: XCTestCase {
         let app = XCUIApplication()
         app.launchArguments = ["--ui-testing"]
         app.launch()
-        app.buttons["addFirstHost"].tapWhenReady()
-        app.textFields["hostName"].typeWhenReady("Viewport")
-        app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
-        app.textFields["hostUsername"].typeWhenReady("tester")
-        app.buttons["saveHost"].tapWhenReady()
+        try app.buttons["addFirstHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Viewport")
+        try app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
+        try app.textFields["hostUsername"].typeWhenReady("tester")
+        try app.buttons["saveHost"].tapWhenReady()
         app.buttons["host-Viewport"].tap()
         XCTAssertTrue(app.secureTextFields["Password"].waitForExistence(timeout: 10))
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         XCTAssertTrue(app.buttons["Reconnect"].waitForExistence(timeout: 5))
         let terminal = app.descendants(matching: .any).matching(identifier: "terminal").firstMatch
         terminal.tap()
@@ -90,7 +90,7 @@ final class iOSSHUITests: XCTestCase {
 
         app.buttons["Reconnect"].tap()
         XCTAssertTrue(app.secureTextFields["Password"].waitForExistence(timeout: 10))
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         terminal.tap()
         try await assertTerminalIsAboveAccessory(app)
 
@@ -130,14 +130,14 @@ final class iOSSHUITests: XCTestCase {
         let app = XCUIApplication()
         app.launchArguments = ["--ui-testing"]
         app.launch()
-        app.buttons["addFirstHost"].tapWhenReady()
-        app.textFields["hostName"].typeWhenReady("Terminal test")
-        app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
-        app.textFields["hostUsername"].typeWhenReady("tester")
-        app.buttons["saveHost"].tapWhenReady()
+        try app.buttons["addFirstHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Terminal test")
+        try app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
+        try app.textFields["hostUsername"].typeWhenReady("tester")
+        try app.buttons["saveHost"].tapWhenReady()
         app.buttons["host-Terminal test"].tap()
         XCTAssertTrue(app.secureTextFields["Password"].waitForExistence(timeout: 10))
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         XCTAssertTrue(app.buttons["Reconnect"].waitForExistence(timeout: 5))
         XCTAssertTrue(app.descendants(matching: .any).matching(identifier: "terminal").firstMatch.exists)
         XCTAssertEqual(app.staticTexts.matching(NSPredicate(format: "label CONTAINS %@", "rendering could not start")).count, 0)
@@ -155,19 +155,19 @@ final class iOSSHUITests: XCTestCase {
         app.launchArguments = ["--ui-testing"]
         app.launch()
         XCTAssertTrue(app.buttons["addFirstHost"].waitForExistence(timeout: 10))
-        app.buttons["addFirstHost"].tapWhenReady()
+        try app.buttons["addFirstHost"].tapWhenReady()
         XCTAssertFalse(app.buttons["saveHost"].isEnabled)
-        app.textFields["hostName"].typeWhenReady("Development")
-        app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
-        app.textFields["hostUsername"].typeWhenReady("developer")
-        app.buttons["saveHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Development")
+        try app.textFields["hostAddress"].typeWhenReady("192.0.2.1")
+        try app.textFields["hostUsername"].typeWhenReady("developer")
+        try app.buttons["saveHost"].tapWhenReady()
         let host = app.buttons["host-Development"]
         XCTAssertTrue(host.waitForExistence(timeout: 5))
         host.swipeRight()
         app.buttons["Edit"].tap()
         XCTAssertEqual(app.textFields["hostAddress"].value as? String, "192.0.2.1")
         XCTAssertEqual(app.textFields["hostUsername"].value as? String, "developer")
-        app.buttons["Cancel"].tapWhenReady()
+        try app.buttons["Cancel"].tapWhenReady()
         host.swipeLeft()
         app.buttons["Delete"].tap()
         XCTAssertTrue(app.buttons["addFirstHost"].waitForExistence(timeout: 5))
@@ -187,10 +187,10 @@ final class iOSSHUITests: XCTestCase {
         XCTAssertTrue(privacyPolicyLink.waitForExistence(timeout: 5))
         XCTAssertTrue(app.descendants(matching: .any)["supportLink"].waitForExistence(timeout: 5))
         app.buttons["Done"].tap()
-        app.buttons["addFirstHost"].tapWhenReady()
-        app.textFields["hostName"].typeWhenReady("Bad host")
-        app.textFields["hostAddress"].typeWhenReady("bad host")
-        app.textFields["hostUsername"].typeWhenReady("root")
+        try app.buttons["addFirstHost"].tapWhenReady()
+        try app.textFields["hostName"].typeWhenReady("Bad host")
+        try app.textFields["hostAddress"].typeWhenReady("bad host")
+        try app.textFields["hostUsername"].typeWhenReady("root")
         XCTAssertFalse(app.buttons["saveHost"].isEnabled)
     }
 }