[Qgis-developer] Adding new provider for QGIS

[Nyall Dawson]

Hi David, (and cc'ing back in qgis-dev)

When you open a pull request against the main QGIS master repo, the
automated test suite (https://travis-ci.org/qgis/QGIS) will kick in and run
a test build and run all the existing unit tests to avoid regressions. It
will also run some "meta" tests, checking code quality and adherence to the
code standards.

So that's the first step - open your PR against QGIS master (not against
your fork), and see how this goes. Then you basically keep revising your
branch and pushing to github and for each new push Travis will retest until
you get a green light.

The next step is adding new tests to cover your work. Without tests it
*will* break in some future QGIS release, so that's why testing is
mandatory for something like this. The provider test also runs a bunch of
complex cases against each provider to ensure that they correctly handle a
bunch of corner cases, so it will help ensure that your provider is well
behaved and stable.

Here's some other provider tests which are good models to copy from:

https://github.com/qgis/QGIS/blob/master/tests/src/python/test_provider_shapefile.py

https://github.com/qgis/QGIS/blob/master/tests/src/python/test_provider_spatialite.py

(Note that both also implement additional tests specific to that provider,
eg testRepack for shapefiles). The ms-sql provider test is a good example
of a minimal test, which only implements the things required for the
generic provider test (although you could also omit the
enableCompiler/disableComplier methods if you haven't implemented an
expression compiler for db2 yet). Then you'll also need to include relevant
test data - see
https://github.com/qgis/QGIS/tree/master/tests/testdata/provider for what's
expected in the test files, eg
https://github.com/qgis/QGIS/blob/master/tests/testdata/provider/testdata_mssql.sql
.

Hope that helps!

Nyall



On 26 Jan 2016 10:05, "David Adler" <dadler at adtechgeospatial.com> wrote:
>
> I'm not clear on what the "automated CI" is or how one runs is.
>
> We did a fork and pull to our fork to do the development.
>
> I'm still a bit hazy on setting up and running the tests.  Does a
database need to be operational in order to run the tests?
test_provider_mssql.py doesn't look like it does much.
>
>
> On 1/25/2016 4:24 PM, Nyall Dawson wrote:
>>
>>
>> On 26 Jan 2016 07:57, "David Adler" <dadler at adtechgeospatial.com> wrote:
>> >
>> > We would like to add a DB2 provider to QGIS so that QGIS users can
access spatial tables on DB2 for LUW and DB2 for z/OS.
>> >
>> > We have implemented and tested much of this based on an existing
database provider.
>> >
>> > What is the mechanism to have this reviewed and approved?
>>
>> Open a pull request on github, and let the automated CI run its checks
over the code.
>>
>> Tips to get things reviewed/merged faster:
>> - Make sure all your API additions are correctly documented
>> - Include unit tests. At a minimum a new vector provider needs a test
which inherits from ProviderTestCase. See
tests/src/python/test_provider_mssql.py for an example. This ensures that
the provider behaves consistently with what QGIS expects from a vector data
provider.
>>
>> Nyall
>>
>> >
>> >
>> >
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