How to use User Keyword Arguments with default values in RobotFramework

Question

Can someone explain me how to use default values for optional keyword arguments in connection with data-driven testcases?

As you can see in my example not all default values are used in some cases:

*** Test Cases ***
| testArgs | [Template] | doSomething
| | 111 : 222 : 333 : 444
| | xxx : 222 : 333 : 444 | xxx
| | 111 : xxx : 333 : 444 | | xxx
| | 111 : xxx : 333 : 444 | ${EMPTY} | xxx
| | None : xxx : 333 : 444 | ${None} | xxx
| | None : xxx : 333 : 444 | ${null} | xxx
| | 111 : 222 : xxx : 444  | | | xxx

*** Keywords ***
| doSomething
| | [Arguments] | ${expected} | ${arg1}=111 | ${arg2}=222 | ${arg3}=333 | ${arg4}=444
| | Log | exp: ${expected}
| | ${rc} | Set Variable | ${arg1} : ${arg2} : ${arg3} : ${arg4}
| | Log | arg: ${rc}
| | Run Keyword If  | '${rc}' == '${expected}'  
| | ... | Log | === equal ===
| | ... | ELSE  
| | ... | Log | !!! diff !!!
| | Log | **************************
| | Should be equal | ${rc} | ${expected}

Result:

testArgs                                                              | FAIL |
Several failures occurred:
1)  : xxx : 333 : 444 != 111 : xxx : 333 : 444
2)  : xxx : 333 : 444 != 111 : xxx : 333 : 444
3)  :  : xxx : 444 != 111 : 222 : xxx : 444

I know that I can use named arguments to set specific keyword arguments. But this is only possible in keyword-driven testcases.

Regards, Tom

Answer 1

Call the specific keyword only with which argument you wanted to pass. eg:

*** Test Cases ***
TEST
    MyKeyword   a=1    c=3

*** Keywords ***
MyKeywords
    [Arguments]   ${a}=0   ${b}=2   ${c}=3

Here, I am not passing argument 'b'. By default it will take b=2

Answer 2

An example from the Robot Framework User Guide:

*** Keywords ***
    Two Arguments With Defaults
    [Arguments]    ${arg1}=default 1    ${arg2}=${VARIABLE}
    [Documentation]    This keyword takes 0-2 arguments
    Log    1st argument ${arg1}
    Log    2nd argument ${arg2}

 *** Test Cases ***
Example
    Two Arguments With Defaults    arg2=new value

So Peter Bingham is right:

*** Test Cases ***
TEST
    MyKeyword   a=1    c=3

*** Keywords ***
MyKeywords
    [Arguments]   ${a}=0   ${b}=2   ${c}=3