@Test
public void testGetNumericAttributeValue_attributeNotPresent() {

    final Variable variable = mock(Variable.class);
    when(variable.findAttribute(anyString())).thenReturn(null);
    final Number value = NcTools.getNumericAttributeValue(variable, "is_not_there");
    assertNull(value);
    verify(variable, times(1)).findAttribute(anyString());
    verifyNoMoreInteractions(variable);
}