BugsnagEvent.unhandled not updated when overridden

[cwalo]

BugsnagEvent.unhandled not updated when overridden

[nickdowell]

Since we don't provide any APIs to create or notify those kind of events, it's going to be difficult to try and write tests for an onSendError handler.

While it is possible to create a "proper" event by calling Bugsnag.notify and capturing the event, that requires Bugsnag.start to have been called beforehand, which could be awkward for unit testing.

func mockAppHang(unhandled: Bool) -> BugsnagEvent {
    var event: BugsnagEvent!
    // Warning: The block will not be called if Bugsnag has not been started
    Bugsnag.notifyError(NSError(domain: "", code: 0, userInfo: nil)) {
        event = $0
        return false
    }
    event.errors[0].errorClass = "App Hang"
    event.errors[0].errorMessage = """
        The app's main thread failed to respond to an event within 2000 milliseconds
        """
    event.unhandled = unhandled
    return event
}

A possible workaround is to break out some of the onSendError logic into a more testable function, e.g.

func onSendError(event: BugsnagEvent) -> Bool {
    shouldSendError(
        errorClass: event.errors.first?.errorClass,
        unhandled: event.unhandled)
}

// This is more testable since it does not need a BugsnagEvent
func shouldSendError(errorClass: String?, unhandled: Bool) -> Bool {
    if unhandled, errorClass == "App Hang" {
        // TODO: notify without sending to Bugsnag
        return false
    }
    return true
}

[nickdowell]

Hi @cwalo this issue is due to BugsnagEvent not implementing a default initializer.

The event created with let event = BugsnagEvent() is missing an internal property that results in the unhandled getter always returning false.

The only supported way to create a BugsnagEvent using our public API is via Bugsnag.notify() or Bugsnag.notifyError():

/// The following test passes
func testUnhandledOverridden() {
    Bugsnag.notifyError(NSError(domain: "", code: 0, userInfo: nil)) { event in
        XCTAssertFalse(event.unhandled)
        event.unhandled = true
        XCTAssertTrue(event.unhandled)
        return false
    }
}

[cwalo]

Ah, that makes sense. In our case we're interested in being notified on non-fatal (handled) app hang events without reporting them to Bugsnag, so I'm trying to write a unit test that validates the return value of the onSendError block we pass to the BugsnagConfiguration using different BugsnagEvent "types". Even with the public API, I'm not seeing a straightforward way to notify Bugsnag of the same errors that it would report itself (e.g. OOMs, app hangs, thermal kills, etc.), since BugsnagError is not convertible to Error. Ideally, I could do something like this:

func mockAppHang(unhandled: Bool) -> BugsnagEvent {
  let error = BugsnagError()
  error.errorClass = "App Hang"
  let event = BugsnagEvent()
  event.errors = [error]
  // set event.unhandled
       
  return event
}

Do you have any suggestions for writing tests for the onSendError handler utilizing different error events?

[cwalo]

Nice! That's a decent workaround and I appreciate the suggestion. Obvious in hindsight 😅

[luke-belton]

@cwalo I've closed this issue for now, but if you have any other questions just let us know 👍