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    Get started with Game Loop tests for iOS

    With Game Loop tests, you can write tests native to your game engine and then run them in Test Lab on devices you choose. This way, you don't need to worry about writing for different UI or testing frameworks. A Game Loop test simulates the actions of a real player, and when you run it on Test Lab , it provides a fast and scalable way to verify that your game performs well for your users.

    This page shows you how to run a Game Loop test, then view and manage your test results in the Test Lab page of the Firebase console. You can also further customize your tests with optional features, such as writing custom test results or ending your test early .

    What is a Game Loop Test?

    A loop is a full or partial run-through of your test on your gaming app. You can run a Game Loop test locally on a simulator or on a set of devices in Test Lab . Game Loop tests can be used to:

    • Run through your game as an end user would play it. You can either script the input of the user, let the user be idle, or replace the user with an AI (for example, if you implemented AI in a car racing game, you can put an AI driver in charge of the user’s input).

    • Run your game at the highest quality setting to find out which devices can support it.

    • Run a technical test, such as compiling multiple shaders, executing them, and checking that the output is as expected.

    Step 1: Register Test Lab ’s custom URL scheme

    First, you must register Firebase Test Lab 's custom URL scheme in your app:

    1. In Xcode, select a project target.

    2. Click the Infotab, then add a new URL type.

    3. In the URL Schemesfield, enter firebase-game-loop . You can also register the custom URL scheme by adding it to your project’s Info.plist configuration file anywhere within the <dict> tag:

       <key>CFBundleURLTypes</key>
 <array>
     <dict>
         <key>CFBundleURLName</key>
         <string></string>
         <key>CFBundleTypeRole</key>
         <string>Editor</string>
         <key>CFBundleURLSchemes</key>
         <array>
             <string>firebase-game-loop</string>
         </array>
     </dict>
 </array>

    Your app is now configured to run a test using Test Lab .

    Step 2 (optional): Configure your app to run multiple loops

    If your app has multiple custom URL schemes registered and you plan to run multiple loops (aka scenarios) in your test, you must specify which loops you want to run in your app at launch time.

    In your app delegate, override the application(_:open:options:) method:

    Swift

      func 
  
 application 
 ( 
 _app 
 : 
  
 UIApplication 
 , 
  
 open 
  
 url 
 : 
  
 URL 
  
 options 
 : 
  
 [ 
 UIApplication 
 . 
 OpenURLOptionsKey 
  
 : 
  
 Any 
 ] 
  
 = 
  
 [:]) 
  
 - 
>  
 Bool 
  
 { 
  
 let 
  
 components 
  
 = 
  
 URLComponents 
 ( 
 url 
 : 
  
 url 
 , 
  
 resolvingAgainstBaseURL 
 : 
  
 true 
 ) 
 ! 
  
 if 
  
 components 
 . 
 scheme 
  
 == 
  
 "firebase-game-loop" 
  
 { 
  
 // ...Enter Game Loop Test logic to override application(_:open:options:). 
  
 } 
  
 return 
  
 true 
 }

    Objective-C

      - 
 ( 
 BOOL 
 ) 
 application: 
 ( 
 UIApplication 
  
 * 
 ) 
 app 
  
 openURL 
 :( 
 NSURL 
  
 * 
 ) 
 url 
  
 options 
 :( 
 NSDictionary 
  
& lt 
 ; 
 UIApplicationOpenURLOptionsKey 
 , 
  
 id&gt 
 ; 
  
 * 
 ) 
 options 
  
 { 
  
 if 
  
 ([ 
 url 
 . 
 scheme 
  
 isEqualToString 
 : 
 ( 
 @"firebase-game-loop" 
 )]) 
  
 { 
  
 // ...Enter Game Loop Test logic to override application(_:open:options:). 
  
 } 
 }

    When you run multiple loops in your test, the current loop is passed as a parameter to the URL used to launch the app. You can also obtain the current loop number by parsing the URLComponents object used to fetch the custom URL scheme:

    Swift

      if 
  
 components 
 . 
 scheme 
  
 == 
  
 "firebase-game-loop" 
  
 { 
  
 // Iterate over all parameters and find the one with the key "scenario". 
  
 let 
  
 scenarioNum 
  
 = 
  
 Int 
 ( 
 components 
 . 
 queryItems 
 !. 
 first 
 ( 
 where 
 : 
  
 { 
  
 $0 
 . 
 name 
  
 == 
  
 "scenario" 
  
 }) 
 ! 
 . 
 value 
 !) 
 ! 
  
 // ...Write logic specific to the current loop (scenarioNum). 
 }

    Objective-C

      if 
  
 ([ 
 url 
 . 
 scheme 
  
 isEqualToString 
 : 
 ( 
 @"firebase-game-loop" 
 )]) 
  
 { 
  
 // Launch the app as part of a game loop. 
  
 NSURLComponents 
  
 * 
 components 
  
 = 
  
 [ 
 NSURLComponents 
  
 componentsWithURL 
 : 
 url 
  
 resolvingAgainstBaseURL 
 : 
 YES 
 ]; 
  
 for 
  
 ( 
 NSURLQueryItem 
  
 * 
 item 
  
 in 
  
 [ 
 components 
  
 queryItems 
 ]) 
  
 { 
  
 if 
  
 ([ 
 item 
 . 
 name 
  
 isEqualToString 
 : 
 @"scenario" 
 ]) 
  
 { 
  
 NSInteger 
  
 scenarioNum 
  
 = 
  
 [ 
 item 
 . 
 value 
  
 integerValue 
 ]; 
  
 // ...Write logic specific to the current loop (scenarioNum). 
  
 } 
  
 } 
 }

    Step 3: Create and run a test

    After you register Test Lab 's custom URL scheme, you can run your test in the Firebase console or with the gcloud beta CLI . If you haven't already, generate an IPA file for your app (you'll need to locate it later).

    Run a test in the Firebase console

    1. If you haven't already, open the Firebase console and create a project.

    2. On the Test Lab page of the Firebase console, click Run Your First Test > Run an iOS Game Loop.

    3. In the Upload Appsection, click Browse, then select your app's IPA file (if you haven’t already, generate an IPA file for your app).

    4. Optional : If you want to run multiple loops (aka scenarios) at a time or select specific loops to run, enter the loop numbers in the Scenariosfield.

      For example, when you enter "1-3, 5", Test Lab runs loops 1, 2, 3, and 5. By default (if you don't enter anything in the Scenariosfield), Test Lab only runs loop 1.

    5. In the Devicessection, select one or more physical devices you want to test your app on, then click Start Tests.

    Run a test with the gcloud beta CLI

    1. If you haven't already, configure your local gcloud SDK environment, then make sure to install the gcloud beta component .

    2. Run the gcloud beta firebase test ios run command and use the following flags to configure the run:

    Flags for Game Loop tests
    --type

    Required : Specifies the type of iOS test you want to run. You can enter test types xctest (default) or game-loop .

    --app

    Required : Absolute path ( Google Cloud Storage or filesystem) to your app’s IPA file. This flag is only valid when running Game Loop tests.

    --scenario-numbers

    The loops (aka scenarios) you want to run in your app. You can enter one loop, a list or loops, or a range of loops. The default loop is 1.

    For example, --scenario-numbers=1-3,5 runs loops 1, 2, 3, and 5.

    --device-model

    The physical device you want to run your test on (find out which available devices you can use).

    --timeout

    The maximum duration you want your test to run. You can enter an integer to represent the duration in seconds, or an integer and enumeration to represent the duration as a longer unit of time.

    For example:

    • --timeout=200 forces your test to terminate when it runs up to 200 seconds.
    • --timeout=1h forces your test to terminate when it runs up to an hour.

    For example, the following command runs a Game Loop test that executes loops 1, 4, 6, 7, and 8 on an iPhone 8 Plus:

    gcloud beta firebase test ios run
 --type game-loop --app path/to/my/App.ipa --scenario-numbers 1,4,6-8
 --device-model=iphone8plus

    For more information on the gcloud CLI, see the reference documentation .

    Run a test locally

    To run your test locally, load your gaming app in a simulator and run:

    xcrun simctl openurl SIMULATOR_UDID 
firebase-game-loop://

    • You can find your simulator's UDID by running the instruments -s devices command.

    • If there is only one simulator running, enter the special string "booted" in place of SIMULATOR_UDID .

    If your test contains multiple loops, you can specify which loop you want to run by passing the loop number to the scenario flag. Note that you can only run one loop at a time when running your test locally. For example, if you want to run loops 1, 2, and 5, you must run a separate command for each loop:

     xcrun simctl openurl SIMULATOR_UDID 
firebase-game-loop://?scenario=1 
 xcrun simctl openurl SIMULATOR_UDID 
firebase-game-loop://?scenario=2 
 xcrun simctl openurl SIMULATOR_UDID 
firebase-game-loop://?scenario=5

    End a test early

    By default, a Game Loop test continues running until it reaches a timeout of five minutes, even when all the loops have been executed. When the timeout is reached, the test ends and cancels any pending loops. You can speed up your test or end it early by calling Test Lab ’s custom URL scheme firebase-game-loop-complete in your app’s AppDelegate. For example:

    Swift

      /// End the loop by calling our custom url scheme. 
 func 
  
 finishLoop 
 () 
  
 { 
  
 let 
  
 url 
  
 = 
  
 URL 
 ( 
 string 
 : 
  
 "firebase-game-loop-complete://" 
 ) 
 ! 
  
 UIApplication 
 . 
 shared 
 . 
 open 
 ( 
 url 
 ) 
 }

    Objective-C

      - 
 ( 
 void 
 ) 
 finishLoop 
  
 { 
  
 UIApplication 
  
 * 
 app 
  
 = 
  
 [ 
 UIApplication 
  
 sharedApplication 
 ]; 
  
 [ 
 app 
  
 openURL 
 : 
 [ 
 NSURL 
  
 URLWithString 
 : 
 @"firebase-game-loop-complete://" 
 ] 
  
 options 
 : 
 @{} 
 completionHandler 
 : 
 ^ 
 ( 
 BOOL 
  
 success 
 ) 
  
 {}]; 
 }

    Your Game Loop test terminates the current loop and executes the next loop. When there are no more loops to run, the test ends.

    Write custom test results

    You can configure your Game Loop test to write custom test results to your device’s file system. This way, when the test starts running, Test Lab stores the result files in a GameLoopsResults directory on your testing device (which you must create yourself). When the test ends, Test Lab moves all files from the GameLoopResults directory to your project's bucket. Keep the following in mind when setting up your test:

    • All result files are uploaded regardless of file type, size, or quantity.

    • Test Lab doesn’t process your test results until all the loops in your test have finished running, so if your test includes multiple loops that write output, make sure you append them to a unique result file or create a result file for each loop. This way, you can avoid overwriting results from a previous loop.

    To set up your test to write custom test results:

    1. In your app's Documents directory, create a directory named GameLoopResults .

    2. From anywhere in your app’s code (e.g., your app delegate), add the following:

      Swift

        /// Write to a results file. 
 func 
  
 writeResults 
 () 
  
 { 
  
 let 
  
 text 
  
 = 
  
 "Greetings from game loops!" 
  
 let 
  
 fileName 
  
 = 
  
 "results.txt" 
  
 let 
  
 fileManager 
  
 = 
  
 FileManager 
 . 
 default 
  
 do 
  
 { 
  
 let 
  
 docs 
  
 = 
  
 try 
  
 fileManager 
 . 
 url 
 ( 
 for 
 : 
  
 . 
 documentDirectory 
 , 
  
 in 
 : 
  
 . 
 userDomainMask 
 , 
  
 appropriateFor 
 : 
  
 nil 
 , 
  
 create 
 : 
  
 true 
 ) 
  
 let 
  
 resultsDir 
  
 = 
  
 docs 
 . 
 appendingPathComponent 
 ( 
 "GameLoopResults" 
 ) 
  
 try 
  
 fileManager 
 . 
 createDirectory 
 ( 
  
 at 
 : 
  
 resultsDir 
 , 
  
 withIntermediateDirectories 
 : 
  
 true 
 , 
  
 attributes 
 : 
  
 nil 
 ) 
  
 let 
  
 fileURL 
  
 = 
  
 resultsDir 
 . 
 appendingPathComponent 
 ( 
 fileName 
 ) 
  
 try 
  
 text 
 . 
 write 
 ( 
 to 
 : 
  
 fileURL 
 , 
  
 atomically 
 : 
  
 false 
 , 
  
 encoding 
 : 
  
 . 
 utf8 
 ) 
  
 } 
  
 catch 
  
 { 
  
 // ...Handle error writing to file. 
  
 } 
 }

      Objective-C

        /// Write to a results file. 
 - 
 ( 
 void 
 ) 
 writeResults: 
 ( 
 NSString 
  
 * 
 ) 
 message 
  
 { 
  
 // Locate and create the results directory (if it doesn't exist already). 
  
 NSFileManager 
  
 * 
 manager 
  
 = 
  
 [ 
 NSFileManager 
  
 defaultManager 
 ]; 
  
 NSURL 
 * 
  
 url 
  
 = 
  
 [[ 
 manager 
  
 URLsForDirectory 
 : 
 NSDocumentDirectory 
  
 inDomains 
 : 
 NSUserDomainMask 
 ] 
  
 lastObject 
 ]; 
  
 NSURL 
 * 
  
 resultsDir 
  
 = 
  
 [ 
 url 
  
 URLByAppendingPathComponent 
 : 
 @"GameLoopResults" 
  
 isDirectory 
 : 
 YES 
 ]; 
  
 [ 
 manager 
  
 createDirectoryAtURL 
 : 
 resultsDir 
  
 withIntermediateDirectories 
 : 
 NO 
  
 attributes 
 : 
 nil 
  
 error 
 : 
 nil 
 ]; 
  
 // Write the result message to a text file. 
  
 NSURL 
 * 
  
 resultFile 
  
 = 
  
 [ 
 resultsDir 
  
 URLByAppendingPathComponent 
 : 
 @"result.txt" 
 ]; 
  
 if 
  
 ([ 
 manager 
  
 fileExistsAtPath 
 : 
 [ 
 resultFile 
  
 path 
 ]]) 
  
 { 
  
 // Append to the existing file 
  
 NSFileHandle 
  
 * 
 handle 
  
 = 
  
 [ 
 NSFileHandle 
  
 fileHandleForWritingToURL 
 : 
 resultFile 
  
 error 
 : 
 nil 
 ]; 
  
 [ 
 handle 
  
 seekToEndOfFile 
 ]; 
  
 [ 
 handle 
  
 writeData 
 : 
 [ 
 message 
  
 dataUsingEncoding 
 : 
 NSUTF8StringEncoding 
 ]]; 
  
 [ 
 handle 
  
 closeFile 
 ]; 
  
 } 
  
 else 
  
 { 
  
 // Create and write to the file. 
  
 [ 
 message 
  
 writeToURL 
 : 
 resultFile 
  
 atomically 
 : 
 NO 
  
 encoding 
 : 
 NSUTF8StringEncoding 
  
 error 
 : 
 nil 
 ]; 
  
 } 
 }
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