Error on ScrollBenchmarks

[andresbelt]

Bug when ScrollBenchmarks is running

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object androidx.test.uiautomator.UiObject2.wait(androidx.test.uiautomator.SearchCondition, long)' on a null object reference

searchCondition and contentList is null

[emrisb]

I was getting that error. Then changed the code like below and it worked.

private fun scroll(compilationMode: CompilationMode) {
        benchmarkRule.measureRepeated(
            packageName = "com.example.macrobenchmark_codelab",
            iterations = 5,
            metrics = listOf(FrameTimingMetric()),
            compilationMode = compilationMode,
            startupMode = StartupMode.COLD,
        ) {
            pressHome()
            startActivityAndWait()
            val contentList = device.findObject(By.res("snack_list"))

            val searchCondition = Until.hasObject(By.res("snack_collection"))
            // Wait until a snack collection item within the list is rendered
            contentList.wait(searchCondition, 5_000)

            // Set gesture margin to avoid triggering gesture navigation
            contentList.setGestureMargin(device.displayWidth / 5)

            // Scroll down the list
            contentList.fling(Direction.DOWN)

            // Wait for the scroll to finish
            device.waitForIdle()
        }
    }

[mlykotom]

Thanks! Feel free to open a pull request :)

[mlykotom]

I think this is actually a bug in the Macrobenchmark library causing this.

[mlykotom]

Actually, it turned out the bug is WAI. The reason is that you can use StartupMode.COLD for startup benchmarks, but the process is killed after the setupBlock, so you can prepare your app (e.g. login), but also start the app cold.

For scrolling benchmark, we generally can't use COLD, because the measure block never won't be cold. Therefore, the apropriate mode is either startupMode = null that won't do anything to the app, or StartupMode.WARM that will restart the activity between each iteration.

[monsterbrain]

I got this error even when without using the startup parameter .. with version upto 1.2.4 ..

It seems like the fix is still in the beta version of 1.3.0. adding the 1.3.0 beta xx version fixes the issue for me.