[OSM-dev] (Multi)Polygon handling

nimix melchiormoos at gmail.com
Fri Jul 13 14:06:18 BST 2012


Peter Wendorff wrote
> 
> 
>> My following of web standards has convinced me it is necessary to define
>> the
>> expected output in every case, including invalid ones, or you will have
>> differing implementations. I've been giving it some thought as to what
>> needs
>> to be tested, and I don't think it's excessive. I'd estimate 25-50 small
>> tests would cover everything.
> +1
> But it should be possible to reject false polygon models.
> So to say:
> - any application "must" deal with correct tagging in the same way 
> (which is defined by the corresponding test cases)
> - if an application interprets wrong polygons, it "must" do it in the 
> way which is defined by the corresponding test cases
> - but(!) every application is allowed to reject these polygons because 
> of errors
> - any application is encouraged to report wrong polygons detected to 
> users who may be able to fix that in the database.
> 
> 


That sounds reasonable. But we need to agree on what is valid and what is
treated as invalid. In the testsuite of closed ways that I commited to
github I defined an output for every case, but I'm not sure if the inputs
are valid. My guess would be:
1) Definitely valid
2) valid
3-5 not sure
6) invalid
7) valid
8) not sure
9) invalid
10) valid
11,12) invalid

For everybody not willing to look on github: 
I'm talking about the polygons in [1] from bottom to top.
[1] https://dl.dropbox.com/u/58628/polygontest.osm

Best regards,
Melchior

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