then:
        output.value == 'some message'
    }

    def writesNullText() {
        when:
        output.text(null)

        then:
        output.value == 'null'
    }

    def writesEndOfLine() {
        when:
        output.println()

        then:
        output.rawValue == SystemProperties.instance.lineSeparator
    }

    def appendsCharacter() {
        when: