[Debian-astro-maintainers] Bug#1011178: python-fitsio: testsuite fails with cfitsio 4.1.0

[Aurelien Jarno]

Source: python-fitsio
Version: 1.1.7+dfsg-1
Severity: normal
Tags: upstream patch
Forwarded: https://github.com/esheldon/fitsio/pull/349

The python-fitsio testsuite fails when ran against cfitsio 4.1.0:

| testCompressPreserveZeros (fitsio.test.TestReadWrite)
| Test writing and reading gzip compressed image ... Warning: CFITSIO does not allow subtractive_dither_2 when using Hcompress algorithm.
| Will use subtractive_dither_1 instead.
| FAIL

...

| ======================================================================
| FAIL: testCompressPreserveZeros (fitsio.test.TestReadWrite)
| Test writing and reading gzip compressed image
| ----------------------------------------------------------------------
| Traceback (most recent call last):
|   File "/usr/lib/python3/dist-packages/fitsio/test.py", line 1375, in testCompressPreserveZeros
|     assert rdata[zind[0], zind[1]] == 0.0
| AssertionError
| 
| ----------------------------------------------------------------------
| Ran 60 tests in 1.072s

A full test log is available:
https://ci.debian.net/data/autopkgtest/testing/amd64/p/python-fitsio/21835539/log.gz

The problem is that cfitsio 4.1.0 removed support for
SUBTRACTIVE_DITHER_2 when using the HCOMPRESS algorithm, which is
exactly (one of) the configuration tested in testCompressPreserveZeros.

The fix is to stop testing the HCOMPRESS algorithm, a fix is available
there:
https://github.com/esheldon/fitsio/pull/349