First, create a custom task that generates MD5 hashes of a configurable set of files.

In a new directory, create a `buildSrc/build.gradle(.kts)` file:

====
include::sample[dir="snippets/workerApi/md5CustomTask/kotlin",files="buildSrc/build.gradle.kts[]"]
include::sample[dir="snippets/workerApi/md5CustomTask/groovy",files="buildSrc/build.gradle[]"]
====

        } else {
            assert configurationCacheReusedIn(output2)
        }

        where:
        api << LauncherApi.values()
    }

    def "Can run tasks from nested included build buildSrc"() {
        given:
        def runTestClass = withIncludedBuildBuildSrcTest(api)

        when:
        def output1 = runTestClass.apply('TestClass1')

        then:
        notThrown(Exception)

     * Runs the given action against a new, empty work graph. This allows tasks to be run while calculating the task graph of the build tree, for example to run `buildSrc` tasks or
     * to build local plugins in an included build.
     */
    @Nonnull(when = When.UNKNOWN)
    <T> T withNewWorkGraph(Function<? super BuildTreeWorkGraph, T> action);

        fixture.assertStateUpdated {
            fileChanged("a/build.gradle")
            fileChanged("b/build.gradle")
            projectConfigured(":buildSrc")
            projectConfigured(":")
            modelsCreated(":a", ":b")
            modelsReused(":", ":buildSrc")
        }

        when:
        executer.withArguments(ENABLE_CLI)
        def model4 = runBuildAction(new FetchCustomModelForEachProjectInParallel())

== Step 1. Understanding Incremental Builds
It's important to know that Gradle optimizes your build in a variety of ways.
One such optimization is called _incremental builds_.

An _incremental build_ is a build that avoids running tasks whose inputs did not change since the previous build, making the execution of such tasks unnecessary.

        notifications.started(EvaluateSettingsBuildOperationType.Details, [settingsDir: file('a').absolutePath, settingsFile: file('a/settings.gradle').absolutePath, buildPath: ":a"])
        notifications.started(EvaluateSettingsBuildOperationType.Details, [settingsDir: file('a/buildSrc').absolutePath, settingsFile: file('a/buildSrc/settings.gradle').absolutePath, buildPath: ":a:buildSrc"])

    }

    def "can depend on task from subproject of composing build"() {
        given:
        createDirs("buildA", "buildA/a1")
        buildA.settingsFile << """
    include 'a1'
"""
        buildA.buildFile << """
    task("top-level") {
        dependsOn ':a1:delegate'
    }

    project(':a1') {
        task delegate {

    @Requires(value = IntegTestPreconditions.NotEmbeddedExecutor, reason = "classloader isolation does not work here in embedded mode")
    @InspectsExecutedTasks
    def "buildSrc classes are not visible to injected classes"() {
        plugin.build()
        def buildSrcSrcDir = file("buildSrc/src/main/groovy/org/gradle/test")

        // these class names intentionally clash with what we are injecting

        given:
        def pluginBuilder = new PluginBuilder(file("plugin"))
        pluginBuilder.addSettingsPlugin """
            settings.gradle.allprojects {
                println "Hello from root build's plugin"
            }
        """, "org.gradle.test.MyPlugin", "MyPlugin"

        pluginBuilder.prepareToExecute()

        settingsFile << """
            includeBuild("plugin")
        """

* The build's output;
* The build's logging (i.e. console output);
* The set of tasks executed by the build and their results (e.g. FAILED, UP-TO-DATE etc.).