def METHOD_NAME(fortran_reader):
    ''' Test that the frontend creates a RoutineSymbol of
    UnknownFortranType for a named interface block when the symbol
    name has already been declared. '''
    test_module = '''
    module test_mod
      type test
      end type test
      interface test
        module procedure test_code
      end interface test
    contains
      function test_code()
      end function test_code
    end module test_mod
    '''
    file_container = fortran_reader.psyir_from_source(test_module)
    container = file_container.children[0]
    assert isinstance(container, Container)
    # type symbol
    assert container.symbol_table.lookup("test")
    test_symbol = container.symbol_table.lookup("test")
    assert isinstance(test_symbol, DataTypeSymbol)
    # interface symbol
    assert container.symbol_table.lookup("_psyclone_internal_test")
    test_symbol = container.symbol_table.lookup("_psyclone_internal_test")
    assert isinstance(test_symbol, RoutineSymbol)
    assert isinstance(test_symbol.datatype, UnknownFortranType)
    assert (test_symbol.datatype.declaration == "interface test\n"
            "  module procedure test_code\n"
            "end interface test")
    assert test_symbol.visibility == Symbol.Visibility.PUBLIC