### Build tree state

"Build tree" is another name for the build definition.
The "build tree state" holds the state for the entire build definition for a single build execution within a session.

The build tree state is managed by the `BuildTreeState` class.
An instance is created at the start of a build execution and discarded at the end of the execution.

### Build state

            assertConfirmationCount(build1)
            assertConfirmationCount(build2)
            assertConfirmationCount(build3)
        }
        replaceSocketReceiver { additionalRequests++ }

        then:
        waitCloseAndFinish(build1)
        build2.waitForFinish()
        build3.waitForFinish()
        assertConfirmationCount(build1)
        assertConfirmationCount(build2)
        assertConfirmationCount(build3)

        expect:
        // Wait for each build to list versions
        httpServer.expectConcurrent(repo.listVersions(), repo.listVersions())
        // Only one build should clone
        repo.expectCloneSomething()

        executer.withTasks('resolve')
        def build1 = executer.start()

        executer.withTasks('resolve')
        def build2 = executer.start()

        build1.waitForFinish()

    @Shared
    def project = TestUtil.builder(temporaryFolder).withName("root").build()
    @Shared
    def child1 = ProjectBuilder.builder().withName("child1").withParent(project).build()
    @Shared
    def child2 = ProjectBuilder.builder().withName("child2").withParent(project).build()

    def "builds model"() {
        def builder = new GradleBuildBuilder(project.services.get(BuildStateRegistry))

        task build1(type:BuildSrcTask) {
            doLast {
                ${server.callFromBuild('build1')}
            }
        }

        task build2(type:BuildSrcTask) {
            doLast {
                ${server.callFromBuild('build2')}
            }
        }
        """

        server.expectConcurrent("build1", "build2")

        when:

    }

    @Test
    void testBuild() {
        Model model = new Model();
        Build build = new Build();
        build.setOutputDirectory("myOutputDirectory");
        model.setBuild(build);
        Build build2 = model.getBuild();
        assertNotNull(build2);
        assertEquals("myOutputDirectory", build2.getOutputDirectory());
        model.setBuild(null);
        assertNull(model.getBuild());
    }

        // Serialize an inner child here so that the BaseObject.childrenTracking is non null
        Build build = model.getBuild();

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try (ObjectOutputStream oos = new ObjectOutputStream(baos)) {
            oos.writeObject(build);
        }

        Build build2;
        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());

        def build1 = executer.start()
        block1.waitForAllPendingCalls()

        // Start build 2 then wait until it has run both 'a' and 'b'.
        executer.withTasks("a", "b", "block2")
        executer.withArgument("--info")
        def build2 = executer.start()
        block2.waitForAllPendingCalls()

        // Finish up build 1 and 2
        block1.releaseAll() // finish build 1 while build 2 is still running

        // Block until second build has produced blue things
        def build2 = executer.withTasks("redThings", "blueThings", "block2").start()
        block2.waitForAllPendingCalls()

        // Finish up first build while second build is still running
        block1.releaseAll()
        def result1 = build1.waitForFinish()

        block2.releaseAll()
        def result2 = build2.waitForFinish()

        then:

        // Finish up build 1 and 2
        block1.releaseAll() // finish build 1 while build 2 is still running
        build1.waitForFinish()
        block2.releaseAll()
        build2.waitForFinish()
    }