============================================================== test session starts ===============================================================
platform linux -- Python 3.9.5, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: /tmp/matplotlib, configfile: pytest.ini
collected 24 items                                                                                                                               

lib/matplotlib/tests/test_backend_pgf.py ........F........sss....                                                                          [100%]

==================================================================== FAILURES ====================================================================
_______________________________________________________________ test_xelatex[pdf] ________________________________________________________________

expected = '/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex-expected.pdf'
actual = '/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf', tol = 0, in_decorator = True

    def compare_images(expected, actual, tol, in_decorator=False):
        """
        Compare two "image" files checking differences within a tolerance.
    
        The two given filenames may point to files which are convertible to
        PNG via the `.converter` dictionary. The underlying RMS is calculated
        with the `.calculate_rms` function.
    
        Parameters
        ----------
        expected : str
            The filename of the expected image.
        actual : str
            The filename of the actual image.
        tol : float
            The tolerance (a color value difference, where 255 is the
            maximal difference).  The test fails if the average pixel
            difference is greater than this value.
        in_decorator : bool
            Determines the output format. If called from image_comparison
            decorator, this should be True. (default=False)
    
        Returns
        -------
        None or dict or str
            Return *None* if the images are equal within the given tolerance.
    
            If the images differ, the return value depends on  *in_decorator*.
            If *in_decorator* is true, a dict with the following entries is
            returned:
    
            - *rms*: The RMS of the image difference.
            - *expected*: The filename of the expected image.
            - *actual*: The filename of the actual image.
            - *diff_image*: The filename of the difference image.
            - *tol*: The comparison tolerance.
    
            Otherwise, a human-readable multi-line string representation of this
            information is returned.
    
        Examples
        --------
        ::
    
            img1 = "./baseline/plot.png"
            img2 = "./output/plot.png"
            compare_images(img1, img2, 0.001)
    
        """
        actual = os.fspath(actual)
        if not os.path.exists(actual):
            raise Exception("Output image %s does not exist." % actual)
        if os.stat(actual).st_size == 0:
            raise Exception("Output image file %s is empty." % actual)
    
        # Convert the image to png
        expected = os.fspath(expected)
        if not os.path.exists(expected):
            raise IOError('Baseline image %r does not exist.' % expected)
        extension = expected.split('.')[-1]
        if extension != 'png':
>           actual = convert(actual, cache=True)

actual     = '/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf'
expected   = '/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex-expected.pdf'
extension  = 'pdf'
in_decorator = True
tol        = 0

lib/matplotlib/testing/compare.py:435: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
lib/matplotlib/testing/compare.py:310: in convert
    converter[path.suffix[1:]](path, newpath)
        cache      = True
        cache_dir  = PosixPath('/home/mgorny/.cache/matplotlib/test_cache')
        cached_path = PosixPath('/home/mgorny/.cache/matplotlib/test_cache/5e7b55f5b7b4068856ffc1421de85fe0.png')
        filename   = '/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf'
        hash_value = '5e7b55f5b7b4068856ffc1421de85fe0'
        newpath    = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex_pdf.png')
        path       = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf')
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <matplotlib.testing.compare._GSConverter object at 0x7ff5847b23a0>
orig = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf')
dest = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex_pdf.png')

    def __call__(self, orig, dest):
        if not self._proc:
            self._proc = subprocess.Popen(
                [mpl._get_executable_info("gs").executable,
                 "-dNOSAFER", "-dNOPAUSE", "-sDEVICE=png16m"],
                # As far as I can see, ghostscript never outputs to stderr.
                stdin=subprocess.PIPE, stdout=subprocess.PIPE)
            try:
                self._read_until(b"\nGS")
            except _ConverterError as err:
                raise OSError("Failed to start Ghostscript") from err
    
        def encode_and_escape(name):
            return (os.fsencode(name)
                    .replace(b"\\", b"\\\\")
                    .replace(b"(", br"\(")
                    .replace(b")", br"\)"))
    
        self._proc.stdin.write(
            b"<< /OutputFile ("
            + encode_and_escape(dest)
            + b") >> setpagedevice ("
            + encode_and_escape(orig)
            + b") run flush\n")
        self._proc.stdin.flush()
        # GS> if nothing left on the stack; GS<n> if n items left on the stack.
        err = self._read_until(b"GS")
        stack = self._read_until(b">")
        if stack or not os.path.exists(dest):
>           stack_size = int(stack[1:]) if stack else 0
E           ValueError: invalid literal for int() with base 10: b'ate missing from Resources.\n        Output may be incorrect.\nGS'

dest       = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex_pdf.png')
encode_and_escape = <function _GSConverter.__call__.<locals>.encode_and_escape at 0x7ff5a467a5e0>
err        = b"Processing pages 1 through 1.\nPage 1\n\n   **** Error 'gs' ignored -- Ext"
orig       = PosixPath('/tmp/matplotlib/result_images/test_backend_pgf/pgf_xelatex.pdf')
self       = <matplotlib.testing.compare._GSConverter object at 0x7ff5847b23a0>
stack      = b'tate missing from Resources.\n        Output may be incorrect.\nGS'

lib/matplotlib/testing/compare.py:160: ValueError
============================================================ short test summary info =============================================================
FAILED lib/matplotlib/tests/test_backend_pgf.py::test_xelatex[pdf] - ValueError: invalid literal for int() with base 10: b'ate missing from Res...
==================================================== 1 failed, 20 passed, 3 skipped in 44.09s ====================================================