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Testing Crash Reporting with Backtrace

Beta release

The Sauce Mobile Beta SDK does not install a crash handler. When you run it with Backtrace (Sauce Labs Error Reporting), Backtrace reports the crash and the SDK records the session up to the crash. The following steps show how to force a crash on iOS to verify that setup end to end. See Using Sauce Mobile Beta with Backtrace for the setup itself.

TestFairy.crash() is a test helper: it force-crashes the app with an invalid memory access. Backtrace captures the crash.

note

crash() is an iOS-only helper. The Android SDK has no equivalent: throw a plain uncaught exception instead (for example, throw new RuntimeException("test crash") from a button handler), as the Sauce Labs My Demo App for Android does.

What You'll Need​

  • A working iOS app project with Backtrace initialized first and the Sauce Mobile Beta SDK started with setServerEndpoint followed by beginWithoutCrashHandler.
  • BacktraceClient.shared assigned before beginWithoutCrashHandler, so that the SDK writes sauce.correlation_id and the other attributes it manages to Backtrace at every session start.
  • A build running on a device or Simulator without the Xcode debugger attached, so the crash reaches Backtrace's crash reporter. See allowsAttachingDebugger in Configuring Backtrace for iOS.
  • Basic knowledge of iOS development using either Objective-C or Swift.

Forcing a Crash​

Add a button that calls crash():

[TestFairy crash];
Example
#import "ViewController.h"
#import "TestFairy.h"

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    UIButton* button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(50, 50, 100, 30);
    [button setTitle:@"Crash" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(crashApp:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

- (IBAction)crashApp:(id)sender {
    [TestFairy crash];
}

@end

Crashing in a Second Session​

One launch can contain several sessions, and the SDK gives each one its own sauce.correlation_id. To confirm that a crash is matched to the session that was running, stop the session and start a new one before you crash:

NSString *first = [TestFairy sessionCorrelationId];
[TestFairy stop];
[TestFairy beginWithoutCrashHandler:@"<sauce-mobile-beta-token>"]; // second session, new id; the endpoint set before the first session still applies
NSString *second = [TestFairy sessionCorrelationId];
NSLog(@"first %@, second %@", first, second);
[TestFairy crash];

Swift

let first = TestFairy.sessionCorrelationId()
TestFairy.stop()
TestFairy.beginWithoutCrashHandler("<sauce-mobile-beta-token>") // second session, new id; the endpoint set before the first session still applies
let second = TestFairy.sessionCorrelationId()
print("first \(first ?? "nil"), second \(second ?? "nil")")
TestFairy.crash()

The two logged values differ. The Backtrace report carries the second value and the URL of the second session. Searching the first value in the session list returns the first recording, which ends at stop() and not at the crash.

Expected Result​

  1. The app terminates immediately. Backtrace's crash reporter writes the report to disk, and the Sauce Mobile Beta session ends at the crash.
  2. Relaunch the app. Backtrace uploads the pending crash report while it initializes, and the Sauce Mobile Beta SDK starts a new session.
  3. In Backtrace, open the new error. Its attributes carry the sauce.correlation_id the SDK generated for the session that was running at the crash, sauce.mobile_beta.session_url pointing at that session's recording, sauce.mobile_beta.session_started set to "true", sauce.sdk.coexistence_mode set to backtrace_crash_owner, and sauce.release and sauce.dist for the build.
  4. In Sauce Labs Mobile App Distribution, search the session list for the same sauce.correlation_id value. Exactly one session matches: the recording that ends at the crash. If you crashed in a second session, the first session's id still leads to the first recording, which ends when you stopped it.

The crash report appears in Backtrace only. The Sauce Labs Mobile App Distribution dashboard shows the session recording that ends at the crash.

note

Backtrace lets you filter or group by sauce.correlation_id only after the attribute is indexed once per project under Project Settings > Attributes, with the UUID format. See Indexing Attributes.