introduce Kotlinx Benchmark tests (copied from #763)

buildSrc/src/main/kotlin/buildsrc/convention/kotlin-jvm.gradle.kts

@@ -11,8 +11,6 @@ plugins {
     id("buildsrc.convention.toolchain-jvm")
 }
 
-// note: all subprojects are currently Kotlin Multiplatform, so this convention plugin is unused
-
 java {
     withJavadocJar()
     withSourcesJar()

settings.gradle.kts

@@ -16,7 +16,8 @@ include(
     ":modules:mockk-agent",
     ":modules:mockk-dsl",
 
-    ":modules:client-tests",
+    ":test-modules:client-tests",
+    ":test-modules:performance-tests",
 )
 
 val androidSdkDetected: Boolean? by extra

test-modules/performance-tests/README.md

@@ -0,0 +1,31 @@
+This is a performance testing setup for `mockk` using [JMH](https://github.com/openjdk/jmh).
+
+### How to run
+
+There are two ways to execute the benchmark code
+
+#### 1. Basic with Gradle
+
+```shell
+./gradlew benchmark
+```
+
+It will use default configuration set in  [build.gradle.kts](build.gradle.kts) and print out the results
+
+#### 2. Advanced with JMH binary
+
+If you want access to more JMH features you can
+
+```shell
+./gradlew mainBenchmarkJar
+```
+
+to build the `.jar` file containing the benchmark code. It will be saved to `./build/benchmarks/main/jars` directory.
+
+From there you can run JMH with all the JMH-specific configuration options form CLI (even on different machine).
+
+```shell
+java -jar ./build/benchmarks/main/jars/performance-tests-main-jmh-<version>.jar -w 1 -i 2 -r 60s -prof jfr
+```
+
+which will attach the JFR profiler (not possible with `kontlinx-benchmark` executed from Gradle)

test-modules/performance-tests/build.gradle.kts

@@ -0,0 +1,30 @@
+import kotlinx.benchmark.gradle.JvmBenchmarkTarget
+import kotlinx.benchmark.gradle.benchmark
+
+plugins {
+    buildsrc.convention.`kotlin-jvm`
+    id("org.jetbrains.kotlinx.benchmark") version "0.4.5"
+}
+
+dependencies {
+    implementation("org.jetbrains.kotlinx:kotlinx-benchmark-runtime:0.4.5")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4")
+    implementation(projects.modules.mockk)
+}
+
+benchmark {
+    configurations {
+        named("main") {
+            iterationTime = 60
+            iterationTimeUnit = "sec"
+            iterations = 2
+            warmups = 1
+        }
+    }
+    targets {
+        register("main") {
+            this as JvmBenchmarkTarget
+            jmhVersion = "1.35"
+        }
+    }
+}

test-modules/performance-tests/src/main/kotlin/io/mockk/performance/JmhTest.kt

@@ -0,0 +1,23 @@
+package io.mockk.performance
+
+import io.mockk.every
+import io.mockk.mockk
+import org.openjdk.jmh.annotations.Benchmark
+import org.openjdk.jmh.annotations.BenchmarkMode
+import org.openjdk.jmh.annotations.Mode
+import org.openjdk.jmh.infra.Blackhole
+
+@BenchmarkMode(Mode.Throughput)
+open class JmhTest {
+
+    @Benchmark
+    fun simpleMockAndStub(blackhole: Blackhole) {
+        val mockedClass: MockedClass = mockk()
+        every { mockedClass.mockedFun() } returns "Hello, mockk!"
+        blackhole.consume(mockedClass)
+    }
+
+    class MockedClass {
+        fun mockedFun(): String = "Hello, world!"
+    }
+}