Custom datatable transformer for cucumber-jvm

Question

I want to create custom datatable transformer in cucumber. This is how my feature looks like:

Given board
| o | _ | _ |
| o | _ | _ |
| o | _ | _ |

And I want to put it into custom object. Let's say that it looks like this:

class Board {

    private List<List<String>> board;

    public Board(List<List<String>> board) {
        this.board = board;
    }

}

My step definition should look like this:

@Given("^board$")
public void board(Board board) throws Throwable {
    // todo
}

Step definition works fine for DataTable class and List<List<String>>

@Given("^board$")
public void board(DataTable board) throws Throwable {
    // this works fine
}

And this also works fine

@Given("^board$")
public void board(List<List<String>> board) throws Throwable {
    // this also works fine
}

I tried to find a solution on the internet but without any success. I also tried to create Transformer but, as I see, it works fine only for strings (I want to use Datatable or List> at the input):

class BoardTransformer extends Transformer<Board> {

    @Override
    public Board transform(String value) {
        // TODO Auto-generated method stub
        return null;
    }

}

What is your cucumber-JVM version? – nilesh Feb 05 '15 at 16:40 — nilesh, Feb 05 '15 at 16:40
You should really upgrade your Cucumber! – M.P. Korstanje Sep 11 '18 at 14:26 — M.P. Korstanje, Sep 11 '18 at 14:26

score 4 · Answer 1 · answered Sep 11 '18 at 14:25

In cucumber 3.x you can use the TypeRegistryConfigurer to inform Cucumber how it should create Board objects from DataTable. Because you want to transform the whole table to a single object you have to use a TableTransformer rather then TableCellTransformer,TableEntryTransformer or TableRowTransformer.

You can place the TypeRegistryConfigurer anywhere on the glue path.

package io.cucumber.java.test;

import io.cucumber.core.api.TypeRegistryConfigurer;
import io.cucumber.core.api.TypeRegistry;
import io.cucumber.datatable.DataTableType;
import io.cucumber.datatable.TableTransformer;

import java.util.List;
import java.util.Locale;

import static java.util.Locale.ENGLISH;

public class TypeRegistryConfiguration implements TypeRegistryConfigurer {

    @Override
    public Locale locale() {
        return ENGLISH;
    }


    @Override
    public void configureTypeRegistry(TypeRegistry typeRegistry) {
        typeRegistry.defineDataTableType(new DataTableType(
            Board.class,
            (TableTransformer<Board>) table -> new Board(table.cells())));

    }

    static class Board {

        private final List<List<String>> board;

        private Board(List<List<String>> board) {
            this.board = board;
        }
    }
}

score 1 · Answer 2 · answered Dec 10 '18 at 09:06

In older version of cucumber, as per your stated 1.2.2, you would have to request a list of your object as each row of the data table (from a feature file perspective) is seen as a different object e.g.

@Given("^board$")
public void board(List<Board> board) throws Throwable {
    // process however you want
}

a lot of cucumber has changed from v3 onwards regarding data tables e.g. switching from XStream to Jackson

but as previously advised, upgrade your Cucumber version if possible

score 0 · Answer 3 · answered Oct 03 '16 at 15:11

0

If you can go with

@Given("^board$")
public void board(List<List<String>> board) throws Throwable {
...

Why don't you just create your Board object right after

Board board2 = new Board(board);

It doen't look like you need a transformer.

answered Oct 03 '16 at 15:11

Jefe infiltrado

364
2
15

A transformer is never "needed" it is just nicer and clearer to not clutter the code with technical details. Your answer does not help much ... – Ar3s Feb 12 '19 at 13:53

score 0 · Answer 4 · answered Sep 10 '18 at 11:51

Assuming the goal is to separate the "nasty parameter transform stuff" from the "actual test code", so that I can use nice objects in my test code, the best I have been able to come up with is to make use of Jackson ObjectMapper (or some other de/serialization lib that supports Map to Object).

For example:

private ObjectMapper objectMapper = new ObjectMapper();

@When("I do some thing with input dataTable")
public void i_do_some_thing_with_input_dataTable(DataTable dataTable) {
    List<Map<String,String>> values = dataTable.asMaps(String.class, String.class);
    List<MyObject> inputs = values.stream().map(i -> objectMapper.convertValue(i,MyObject.class)).collect(Collectors.toList());

    inputs.forEach(i-> {
        //Do things with the input.
    });
}

You can/should ofcourse wrap this conversion in some nice service class that you can inject into / instantiate in your test.

This code assumes the following:

you are using data tables with headers
you have fields in MyObject with names that correspond to the headers in the table
MyObject has appropriate getter/setters for each field.

Custom datatable transformer for cucumber-jvm

4 Answers4