@Test
public void applyReturnsDefaultPlaceholder() {

    final PipelineElement input = PipelineElement.unresolved();
    final String params = "(" + KNOWN_PLACEHOLDER + ")";
    when(expressionResolver.resolveAsPipelineElement(anyString()))
            .thenReturn(PipelineElement.resolved(KNOWN_VALUE));
    assertThat(function.apply(input, params, expressionResolver)).contains(KNOWN_VALUE);
    verify(expressionResolver).resolveAsPipelineElement(KNOWN_PLACEHOLDER);
}