when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }


    def "supplies no installations for wrong os"() {
        given:
        def supplier = new OsXInstallationSupplier(OperatingSystem.WINDOWS, osxJavaHomeCommand)

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

    def "supplies no installations for non-existing directory"() {
        given:
        assert candidates.deleteDir()

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

    def "supplies single installations for single candidate"() {
        def jdk = temporaryFolder.createDir("11.0.6.hs-adpt")
        given:
        def supplier = createSupplier([jdk] as Set)

        when:
        def directories = supplier.get()

        then:

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }


    def "supplies no installations for empty directory"() {
        given:
        def supplier = new LinuxInstallationSupplier(OperatingSystem.LINUX, emptyDir)

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

    def "supplies no installations for non-existing directory"() {
        given:
        assert candidates.deleteDir()

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

    def "supplies no installations for non-existing directory"() {
        given:
        assert candidates.deleteDir()

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        buildOptions.getJavaInstallationsFromEnvironment() >> ["JDK8", "JDK9"]
        def directories = consistentOrder(supplier.get())

        then:
        directories.size() == 2
        directories[0].location == jdk8
        directories[0].source == "environment variable 'JDK8'"
        directories[1].location == jdk9
        directories[1].source == "environment variable 'JDK9'"
    }

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

    def "supplies no installations for non-existing directory"() {
        given:
        assert candidates.deleteDir()

        when:
        def directories = supplier.get()

        then:
        directories.isEmpty()
    }

        when:
        def directories = supplier.get()

        then:
        directoriesAsStablePaths(directories) == stablePaths([new File("/usr/lib/jvm/adoptopenjdk-16.jdk").absolutePath])
        directories*.source == ["Maven Toolchains"]

        where:

 * Build root directories are always watchable hierarchies.
 * Watching the build root directories is better since they are less likely to be deleted and
 * nearly no changes to the watched directories are necessary when running builds on the same project.
 *