BenchmarkRule

class BenchmarkRule : TestRule

JUnit rule for benchmarking code on an Android device.

In Kotlin, benchmark with measureRepeated. In Java, use getState.

Benchmark results will be output:

  • Summary in Android Studio in the test log

  • In JSON format, on the host

  • In simple form in Logcat with the tag "Benchmark"

Every test in the Class using this @Rule must contain a single benchmark.

See the Benchmark Guide for more information on writing Benchmarks.

import androidx.benchmark.junit4.BenchmarkRule
import androidx.benchmark.junit4.measureRepeated
import androidx.test.ext.junit.runners.AndroidJUnit4

@RunWith(AndroidJUnit4::class)
class MyBenchmark {
    @get:Rule val benchmarkRule = BenchmarkRule()

    @Test
    fun measureWork() {
        benchmarkRule.measureRepeated { doSomeWork() }
    }
}

Summary

Nested types

Handle used for controlling measurement during measureRepeated.

Public constructors

Public functions
open Statement
apply(base: Statement, description: Description)
BenchmarkState

Object used for benchmarking in Java.

Public properties
MicrobenchmarkConfig

Extension functions
inline Unit

Benchmark a block of code.
inline Unit

Benchmark a block of code, which runs on the main thread, and can safely interact with UI.

Public constructors

BenchmarkRule

Added in 1.0.0
BenchmarkRule()

BenchmarkRule

Added in 1.2.0
@ExperimentalBenchmarkConfigApi
BenchmarkRule(config: MicrobenchmarkConfig)

Public functions

apply

Added in 1.0.0
open fun apply(base: Statement, description: Description): Statement

getState

Added in 1.0.0
fun getState(): BenchmarkState

Object used for benchmarking in Java.

@Rule
public BenchmarkRule benchmarkRule = new BenchmarkRule();

@Test
public void myBenchmark() {
    ...
    BenchmarkState state = benchmarkRule.getBenchmarkState();
    while (state.keepRunning()) {
        doSomeWork();
    }
    ...
}
Throws
kotlin.IllegalStateException

if the BenchmarkRule isn't correctly applied to a test.

Public properties

config

Added in 1.4.0-rc01
val config: MicrobenchmarkConfig

Extension functions

measureRepeated

inline fun BenchmarkRule.measureRepeated(crossinline block: BenchmarkRule.Scope.() -> Unit): Unit

Benchmark a block of code.

import androidx.benchmark.junit4.BenchmarkRule
import androidx.benchmark.junit4.measureRepeated
import androidx.test.ext.junit.runners.AndroidJUnit4

@RunWith(AndroidJUnit4::class)
class MyBenchmark {
    @get:Rule val benchmarkRule = BenchmarkRule()

    @Test
    fun measureWork() {
        benchmarkRule.measureRepeated { doSomeWork() }
    }
}
Parameters
crossinline block: BenchmarkRule.Scope.() -> Unit

The block of code to benchmark.

measureRepeatedOnMainThread

inline fun BenchmarkRule.measureRepeatedOnMainThread(crossinline block: BenchmarkRule.Scope.() -> Unit): Unit

Benchmark a block of code, which runs on the main thread, and can safely interact with UI.

While @UiThreadRule works for a standard test, it doesn't work for benchmarks of arbitrary duration, as they may run for much more than 5 seconds and suffer ANRs, especially in continuous runs.

import androidx.benchmark.junit4.BenchmarkRule
import androidx.benchmark.junit4.measureRepeated
import androidx.benchmark.junit4.measureRepeatedOnMainThread
import androidx.test.ext.junit.runners.AndroidJUnit4

@RunWith(AndroidJUnit4::class)
class MainThreadBenchmark {
    @get:Rule val benchmarkRule = BenchmarkRule()

    @Test
    fun measureWork() {
        benchmarkRule.measureRepeatedOnMainThread {
            // this block is run on the main thread
            doSomeWorkOnMainThread()
        }
    }
}
Parameters
crossinline block: BenchmarkRule.Scope.() -> Unit

The block of code to benchmark.
Throws
java.lang.Throwable

when an exception is thrown on the main thread.
kotlin.IllegalStateException

if a hard deadline is exceeded while the block is running on the main thread.