writing unit test for calc functions

Markus Mohrhard markus.mohrhard at googlemail.com
Sat Apr 16 22:33:06 UTC 2016

Hey Winfried,

On Sat, Apr 16, 2016 at 5:29 PM, Winfried Donkers <
winfried.libreoffice at gmail.com> wrote:

> Hi Markus,
> @Winfried: You are writing most of the spreadsheet functions right now.
>> Would that be something that would help you add tests for all new
>> functions? You could add your test cases directly in the spreadsheet and
>> use it for manual checking as well as later for an automated test.
> I would like to add unit tests like
> sc/qa/unit/data/xlsx/functions-excel-2010.xlsx and tested in
> sc/qa/unit/subsequent_export-test.cxx (test principle conceived by Kohei),
> e.g. no csv files but an xlsx-document saved by Excel. The document
> contains boolean verifications is such a way that one cell (here Sheet1.E2)
> needs to be checked in the unit test for all functions in the document.
> Only if that cell contains a false value, the individual verifications for
> each function needs to be traversed to provide a message which function(s)
> went wrong.
> With the xlsx, both excel-import of the function and the function itself
> are tested.
> As at that time csv files were to be used for testing the special cases
> and various use cases of each function, and Raal seemed to pick up that
> part, I never went farther than the above-mentioned xlsx-document.
> Of course the principle as used in the above test file can perfectly be
> used for more elaborate unit tests, removing the need for csv files. it is
> also possible for non-developers to create these test files, as long as the
> 'verification cells' are in a fixed row or column. The only developer
> action needed would be to include the file, like in
> sc/qa/unit/subsequent_export-test.cxx for the excel2010/2013 functions.
> For the Excel2016 functions, on which I have bee working since last
> autumn, the FORECAST_ETS functions present a problem for me as far as
> testing is concerned. The results of the functions depend on the algorithms
> used (and thresholds used) to find optimum values for coefficients, and
> will always differ between Excel and Calc. Even with Calc I can imagine an
> improvement of the algorithm leading to different results. It wouldn't seem
> right to have to modify the unit test as well in that case. As for the
> other functions, There still being developed/evaluated and unit tests are
> on my to-do-list, just a providing a basis for Calc help.

Well the advantage would be that you could write the document while you
implement the function. You can add all the test cases that you would
normally use for manual checking into that document and at the end when
everything works just include it into the automated testing.

> One (personal) remark: deciding which use cases, which values, etc. to use
> for unit tests is a bit of a vague area for me. Arguments can be of
> different types (e.g. string, double, single/double external/internal
> reference, matrix, single value or range), can have almost unlimited
> different values and can be optional. Testing all use cases would fill a
> lot of cells and doesn't seem practical to me. But for deciding which use
> cases to test and which to skip clear guidelines would be a great help (for
> me at least).

Ideally all special cases would be tested. It does not matter how many
cases that are and of course we don't need all at once but in an ideal
world you have a test case for each possible branch in the code. Basically
while implementing a new function I would add at least tests for all the
special cases that I encounter during the implementation, e.g. handling for
optional parameters, special handling for some values, ... Normally you
need to write such a test anyway for your manual tests as you need to
manually test your change. The difference to our present workflow would
just be that instead of doing this in a temporary document that you throw
away at some point you just collect all these cases and include them in the
test framework.

> Does all this match with your ideas?

Yes, I think we basically agree. I'll see that I work on a template that
can be used and that makes it easy to write such tests.

> Winfried
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