property.set(null)
    }

    protected void nullConvention(def property) {
        property.convention(null)
    }

    def host = Mock(PropertyHost)

    protected void assertPropertyValueIs(T expected, PropertyInternal<?> property) {
        assert property.present
        T actual = property.get()
        assertEqualValues(expected, actual)
    }

        property.convention((Iterable) null)
    }

    def property = property()

    protected void assertValueIs(C expected, PropertyInternal<?> property = this.property) {
        assertPropertyValueIs(expected, property)
    }

    protected void assertEqualValues(C expected, C actual) {
        assert actual instanceof ImmutableCollection
        assert immutableCollectionType.isInstance(actual)

        return brokenSupplier(String)
    }

    protected void assertValueIs(Map<String, String> expected, MapProperty<String, String> property = this.property) {
        assertPropertyValueIs(expected, property)
    }

    protected void assertEqualValues(Map<String, String> expected, Map<String, String> actual) {
        actual.each {
            assert it.key instanceof String