datatable-java: Header only datatable does not convert to empty list

[lsuski]

Summary

In cucumber v2 header only datatables | firstName | lastName | birthDate | converts to empty list. In cucumber v4.2.0 there is exception thrown in such case.
This could have changed in be42d30. @mpkorstanje could you tell if this is really a bug or expected behaviour currently.
However converting List<Map<String, Integer>> in such case works.

Possible Solution

Change DataTableTypeRegistryTableConverter to handle this situation

[mpkorstanje]

I'm having trouble working out why you'd get an error. Can you include the error, your step definition and your type registry configuration?

[lsuski]

I'm using only default converters. Add this test to DataTableTypeRegistryTableConverterTest

 @Test
    public void convert_to_empty_list__only_header() {
        final DataTable table = parse("",
                                      " | firstName | lastName | birthDate |"
        );
        assertEquals(emptyList(), converter.convert(table, LIST_OF_AUTHOR));
    }

It fails although this test convert_to_empty_maps__only_header passes

[mpkorstanje]

Cheers. That made it easy to spot. I'll have to think about the solution. It's a bit hard to explain.

[mpkorstanje]

What do you think of this? https://github.com/cucumber/cucumber/pull/540/files

Because of it convert_to_list_of_primitive will no longer works for tables that are too wide. Those couldn't ever be lists of primitives anyway. But we were doing it anyway. A behavior inherited from the original data table but undesirable in hindsight.

[lsuski]

Looks good for me

[stale]

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