this.buildStateFactory = buildStateFactory;
    }

    @Override
    public RootBuildState getRootBuild() {
        if (rootBuild == null) {
            throw new IllegalStateException("Root build is not defined.");
        }
        return rootBuild;
    }

    @Override
    public RootBuildState createRootBuild(BuildDefinition buildDefinition) {
        if (rootBuild != null) {

        return includedBuild
    }

    RootBuildState rootBuild(TestFile rootDir = tmpDir.createDir("root-dir")) {
        def settings = Stub(SettingsInternal)
        def gradle = Stub(GradleInternal)
        def buildController = buildController(settings, gradle)
        def build = Stub(RootBuildState)

        services.add(buildController)

            this.rootProject = rootProject
        }
    }

    class RootBuildFixture {
        final RootBuildState state
        final ProjectState rootProject
        final ProjectState defaultProject
        final Set<ProjectState> rootChildProjects

        RootBuildFixture(RootBuildState state, ProjectState rootProject, Set<ProjectState> rootChildProjects, ProjectState defaultProject) {
            this.state = state

import org.gradle.execution.TaskSelector;
import org.gradle.internal.build.BuildState;
import org.gradle.internal.build.BuildStateRegistry;
import org.gradle.internal.build.IncludedBuildState;
import org.gradle.internal.build.RootBuildState;
import org.gradle.util.Path;
import org.gradle.util.internal.NameMatcher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nullable;
import javax.inject.Inject;

            graphBuilder?.invoke(builder, rootBuildState())

            for (build in builds) {
                if (build is BuildWithWork) {
                    builder.withWorkGraph(build.build.state) {
                        it.setScheduledWork(build.workGraph)
                    }
                }
            }
        }
    }

    private
    fun rootBuildState() =
        host.service<BuildState>()

import org.gradle.internal.build.BuildModelControllerServices;
import org.gradle.internal.build.BuildState;
import org.gradle.internal.build.BuildStateRegistry;
import org.gradle.internal.build.RootBuildState;
import org.gradle.internal.buildprocess.BuildProcessScopeServices;
import org.gradle.internal.buildtree.BuildTreeLifecycleController;
import org.gradle.internal.buildtree.BuildTreeModelControllerServices;