Delay/Wait in a test case of Xcode UI testing
IosIos9Xcode Ui-TestingXcode7 Beta2XctwaiterIos Problem Overview
I am trying to write a test case using the new UI Testing available in Xcode 7 beta 2. The App has a login screen where it makes a call to the server to login. There is a delay associated with this as it is an asynchronous operation.
Is there a way to cause a delay or wait mechanism in the XCTestCase before proceeding to further steps?
There is no proper documentation available and I went through the Header files of the classes. Was not able to find anything related to this.
Any ideas/suggestions?
Ios Solutions
Solution 1 - Ios
Additionally, you can just sleep:
sleep(10)
Since the UITests run in another process, this works. I don’t know how advisable it is, but it works.
Solution 2 - Ios
Asynchronous UI Testing was introduced in Xcode 7 Beta 4. To wait for a label with the text "Hello, world!" to appear you can do the following:
let app = XCUIApplication()
app.launch()
let label = app.staticTexts["Hello, world!"]
let exists = NSPredicate(format: "exists == 1")
expectationForPredicate(exists, evaluatedWithObject: label, handler: nil)
waitForExpectationsWithTimeout(5, handler: nil)
More details about UI Testing can be found on my blog.
Solution 3 - Ios
iOS 11 / Xcode 9
<#yourElement#>.waitForExistence(timeout: 5)
This is a great replacement for all the custom implementations on this site!
Be sure to have a look at my answer here: https://stackoverflow.com/a/48937714/971329. There I describe an alternative to waiting for requests which will greatly reduce the time your tests are running!
Solution 4 - Ios
Xcode 9 introduced new tricks with XCTWaiter
Test case waits explicitly
wait(for: [documentExpectation], timeout: 10)
Waiter instance delegates to test
XCTWaiter(delegate: self).wait(for: [documentExpectation], timeout: 10)
Waiter class returns result
let result = XCTWaiter.wait(for: [documentExpectation], timeout: 10)
switch(result) {
case .completed:
//all expectations were fulfilled before timeout!
case .timedOut:
//timed out before all of its expectations were fulfilled
case .incorrectOrder:
//expectations were not fulfilled in the required order
case .invertedFulfillment:
//an inverted expectation was fulfilled
case .interrupted:
//waiter was interrupted before completed or timedOut
}
sample usage
Before Xcode 9
Objective C
- (void)waitForElementToAppear:(XCUIElement *)element withTimeout:(NSTimeInterval)timeout
{
NSUInteger line = __LINE__;
NSString *file = [NSString stringWithUTF8String:__FILE__];
NSPredicate *existsPredicate = [NSPredicate predicateWithFormat:@"exists == true"];
[self expectationForPredicate:existsPredicate evaluatedWithObject:element handler:nil];
[self waitForExpectationsWithTimeout:timeout handler:^(NSError * _Nullable error) {
if (error != nil) {
NSString *message = [NSString stringWithFormat:@"Failed to find %@ after %f seconds",element,timeout];
[self recordFailureWithDescription:message inFile:file atLine:line expected:YES];
}
}];
}
USAGE
XCUIElement *element = app.staticTexts["Name of your element"];
[self waitForElementToAppear:element withTimeout:5];
Swift
func waitForElementToAppear(element: XCUIElement, timeout: NSTimeInterval = 5, file: String = #file, line: UInt = #line) {
let existsPredicate = NSPredicate(format: "exists == true")
expectationForPredicate(existsPredicate,
evaluatedWithObject: element, handler: nil)
waitForExpectationsWithTimeout(timeout) { (error) -> Void in
if (error != nil) {
let message = "Failed to find \(element) after \(timeout) seconds."
self.recordFailureWithDescription(message, inFile: file, atLine: line, expected: true)
}
}
}
USAGE
let element = app.staticTexts["Name of your element"]
self.waitForElementToAppear(element)
or
let element = app.staticTexts["Name of your element"]
self.waitForElementToAppear(element, timeout: 10)
Solution 5 - Ios
As of Xcode 8.3, we can use XCTWaiter
http://masilotti.com/xctest-waiting/
func waitForElementToAppear(_ element: XCUIElement) -> Bool {
let predicate = NSPredicate(format: "exists == true")
let expectation = expectation(for: predicate, evaluatedWith: element,
handler: nil)
let result = XCTWaiter().wait(for: [expectation], timeout: 5)
return result == .completed
}
Another trick is to write a wait
function, credit goes to John Sundell for showing it to me
extension XCTestCase {
func wait(for duration: TimeInterval) {
let waitExpectation = expectation(description: "Waiting")
let when = DispatchTime.now() + duration
DispatchQueue.main.asyncAfter(deadline: when) {
waitExpectation.fulfill()
}
// We use a buffer here to avoid flakiness with Timer on CI
waitForExpectations(timeout: duration + 0.5)
}
}
and use it like
func testOpenLink() {
let delegate = UIApplication.shared.delegate as! AppDelegate
let route = RouteMock()
UIApplication.shared.open(linkUrl, options: [:], completionHandler: nil)
wait(for: 1)
XCTAssertNotNil(route.location)
}
Solution 6 - Ios
Based on @Ted's answer, I've used this extension:
extension XCTestCase {
// Based on https://stackoverflow.com/a/33855219
func waitFor<T>(object: T, timeout: TimeInterval = 5, file: String = #file, line: UInt = #line, expectationPredicate: @escaping (T) -> Bool) {
let predicate = NSPredicate { obj, _ in
expectationPredicate(obj as! T)
}
expectation(for: predicate, evaluatedWith: object, handler: nil)
waitForExpectations(timeout: timeout) { error in
if (error != nil) {
let message = "Failed to fulful expectation block for \(object) after \(timeout) seconds."
let location = XCTSourceCodeLocation(filePath: file, lineNumber: line)
let issue = XCTIssue(type: .assertionFailure, compactDescription: message, detailedDescription: nil, sourceCodeContext: .init(location: location), associatedError: nil, attachments: [])
self.record(issue)
}
}
}
}
You can use it like this
let element = app.staticTexts["Name of your element"]
waitFor(object: element) { $0.exists }
It also allows for waiting for an element to disappear, or any other property to change (by using the appropriate block)
waitFor(object: element) { !$0.exists } // Wait for it to disappear
Solution 7 - Ios
This will create a delay without putting the thread to sleep or throwing an error on timeout:
let delayExpectation = XCTestExpectation()
delayExpectation.isInverted = true
wait(for: [delayExpectation], timeout: 5)
Because the expectation is inverted, it will timeout quietly.
Solution 8 - Ios
Edit:
It actually just occurred to me that in Xcode 7b4, UI testing now has
expectationForPredicate:evaluatedWithObject:handler:
Original:
Another way is to spin the run loop for a set amount of time. Really only useful if you know how much (estimated) time you'll need to wait for
Obj-C:
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow: <<time to wait in seconds>>]]
Swift:
NSRunLoop.currentRunLoop().runMode(NSDefaultRunLoopMode, beforeDate: NSDate(timeIntervalSinceNow: <<time to wait in seconds>>))
This is not super useful if you need to test some conditions in order to continue your test. To run conditional checks, use a while
loop.
Solution 9 - Ios
Xcode testing Wait
In my case sleep
created a side effect so I used wait
let _ = XCTWaiter.wait(for: [XCTestExpectation(description: "Hello World!")], timeout: 2.0)
Solution 10 - Ios
How we're doing it at my current company is we create an XCUIElement expression expectation (to create a versatile wait method). We do it the following way to make sure it's maintainable (lots of expectation variety, and don't want to create lots of methods/specific predicates to do so.
Swift 5
Base method
The expression is used to form a dynamic predicate value. We can create XCTNSPredicateExpectation
's from predicates, which we then pass into XCTWaiter
to explicitly wait. If the result was anything other than completed
, then we fail with an optional message.
@discardableResult
func wait(
until expression: @escaping (XCUIElement) -> Bool,
timeout: TimeInterval = 15,
message: @autoclosure () -> String = "",
file: StaticString = #file,
line: UInt = #line
) -> Self {
if expression(self) {
return self
}
let predicate = NSPredicate { _, _ in
expression(self)
}
let expectation = XCTNSPredicateExpectation(predicate: predicate, object: nil)
let result = XCTWaiter().wait(for: [expectation], timeout: timeout)
if result != .completed {
XCTFail(
message().isEmpty ? "expectation not matched after waiting" : message(),
file: file,
line: line
)
}
return self
}
Usage
app.buttons["my_button"].wait(until: { $0.exists })
app.buttons["my_button"].wait(until: { $0.isHittable })
Keypaths
Then we wrap that in a method where a keyPath and match
value form the expression.
@discardableResult
func wait<Value: Equatable>(
until keyPath: KeyPath<XCUIElement, Value>,
matches match: Value,
timeout: TimeInterval = 15,
message: @autoclosure () -> String = "",
file: StaticString = #file,
line: UInt = #line
) -> Self {
wait(
until: { $0[keyPath: keyPath] == match },
timeout: timeout,
message: message,
file: file,
line: line
)
}
Usage
app.buttons["my_button"].wait(until: \.exists, matches: true)
app.buttons["my_button"].wait(until: \.isHittable, matches: false)
Then you can wrap that method, where the match
value is always true
for a use case I found most common.
Usage
app.buttons["my_button"].wait(until: \.exists)
app.buttons["my_button"].wait(until: \.isHittable)
I wrote a post about it, and get the full extension file there too: https://sourcediving.com/clean-waiting-in-xcuitest-43bab495230f
Solution 11 - Ios
The following code just works with Objective C.
- (void)wait:(NSUInteger)interval {
XCTestExpectation *expectation = [self expectationWithDescription:@"wait"];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(interval * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[expectation fulfill];
});
[self waitForExpectationsWithTimeout:interval handler:nil];
}
Just make call to this function as given below.
[self wait: 10];
Solution 12 - Ios
sleep will block the thread
"No run loop processing occurs while the thread is blocked."
you can use waitForExistence
let app = XCUIApplication()
app.launch()
if let label = app.staticTexts["Hello, world!"] {
label.waitForExistence(timeout: 5)
}
Solution 13 - Ios
According to the API for XCUIElement .exists
can be used to check if a query exists or not so the following syntax could be useful in some cases!
let app = XCUIApplication()
app.launch()
let label = app.staticTexts["Hello, world!"]
while !label.exists {
sleep(1)
}
If you are confident that your expectation will be met eventually you could try running this. It should be noted that crashing might be preferable if the wait is too long in which case waitForExpectationsWithTimeout(_,handler:_)
from @Joe Masilotti's post should be used.
Solution 14 - Ios
let app = XCUIApplication()
app.launch()
//Find the button in the UI
let SettingsButton =
app.navigationBars["HomeView"].buttons["Settings"]
XCTAssertTrue(settingButton.waitForExistence(timeout: 10))