WeasyPrint v57.0: failures in test_gradient.py

[FelixSchwarz]

I tried to update WeasyPrint to v57 in Fedora rawhide but there are two failures in test_gradient.py (build server results). Full build logs (including versions) via koji but I extracted the pytest output so maybe you can see the problem quicker that way:

=================================== FAILURES ===================================
___________________________ test_linear_gradients_5 ____________________________
assert_pixels = <function assert_pixels.<locals>.<lambda> at 0x7f4f2333cd60>
    @assert_no_logs
    def test_linear_gradients_5(assert_pixels):
>       assert_pixels('''
            rBrrrBrrrB
            rBrrrBrrrB
            rBrrrBrrrB
            rBrrrBrrrB
            rBrrrBrrrB
        ''', '''
          <style>@page { size: 10px 5px; background: repeating-linear-gradient(
          to right, blue 50%, blue 60%, red 60%, red 90%
        )''')
/builddir/build/BUILD/weasyprint-57.0/tests/draw/test_gradient.py:68: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/builddir/build/BUILD/weasyprint-57.0/tests/conftest.py:98: in <lambda>
    return lambda *args, **kwargs: draw.assert_pixels(
/builddir/build/BUILD/weasyprint-57.0/tests/draw/__init__.py:55: in assert_pixels
    assert_pixels_equal(name, width, height, pixels, expected_pixels)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'linear_gradients_5', width = 10, height = 5
raw = <ImagingCore object at 0x7f4f24552db0>
expected_raw = [(255, 0, 0), (0, 0, 255), (255, 0, 0), (255, 0, 0), (255, 0, 0), (0, 0, 255), ...]
tolerance = 0
    def assert_pixels_equal(name, width, height, raw, expected_raw, tolerance=0):
        """Take 2 matrices of pixels and assert that they are the same."""
        if raw != expected_raw:  # pragma: no cover
            pixels = zip_longest(raw, expected_raw, fillvalue=(-1, -1, -1))
            for i, (value, expected) in enumerate(pixels):
                if expected is None:
                    continue
                if any(abs(value - expected) > tolerance
                       for value, expected in zip(value, expected)):
                    actual_height = len(raw) // width
                    write_png(name, raw, width, actual_height)
                    expected_raw = [
                        pixel or (255, 255, 255) for pixel in expected_raw]
                    write_png(f'{name}.expected', expected_raw, width, height)
                    x = i % width
                    y = i // width
>                   assert 0, (
                        f'Pixel ({x}, {y}) in {name}: '
                        f'expected rgba{expected}, got rgba{value}')
E                   AssertionError: Pixel (0, 0) in linear_gradients_5: expected rgba(255, 0, 0), got rgba(255, 255, 255)
/builddir/build/BUILD/weasyprint-57.0/tests/draw/__init__.py:104: AssertionError
------------------------------ Captured log call -------------------------------
...
___________________________ test_linear_gradients_12 ___________________________
assert_pixels = <function assert_pixels.<locals>.<lambda> at 0x7f4f21f2b060>
    @assert_no_logs
    def test_linear_gradients_12(assert_pixels):
>       assert_pixels('''
            BBBBBBBBB
            BBBBBBBBB
            BBBBBBBBB
            BBBBBBBBB
            BBBBBBBBB
        ''', '''<style>@page { size: 9px 5px; background:
          repeating-linear-gradient(to right, red 3px, blue 3px, blue 4px, red 4px
        )''')
/builddir/build/BUILD/weasyprint-57.0/tests/draw/test_gradient.py:159: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/builddir/build/BUILD/weasyprint-57.0/tests/conftest.py:98: in <lambda>
    return lambda *args, **kwargs: draw.assert_pixels(
/builddir/build/BUILD/weasyprint-57.0/tests/draw/__init__.py:55: in assert_pixels
    assert_pixels_equal(name, width, height, pixels, expected_pixels)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'linear_gradients_12', width = 9, height = 5
raw = <ImagingCore object at 0x7f4f23bbb550>
expected_raw = [(0, 0, 255), (0, 0, 255), (0, 0, 255), (0, 0, 255), (0, 0, 255), (0, 0, 255), ...]
tolerance = 0
    def assert_pixels_equal(name, width, height, raw, expected_raw, tolerance=0):
        """Take 2 matrices of pixels and assert that they are the same."""
        if raw != expected_raw:  # pragma: no cover
            pixels = zip_longest(raw, expected_raw, fillvalue=(-1, -1, -1))
            for i, (value, expected) in enumerate(pixels):
                if expected is None:
                    continue
                if any(abs(value - expected) > tolerance
                       for value, expected in zip(value, expected)):
                    actual_height = len(raw) // width
                    write_png(name, raw, width, actual_height)
                    expected_raw = [
                        pixel or (255, 255, 255) for pixel in expected_raw]
                    write_png(f'{name}.expected', expected_raw, width, height)
                    x = i % width
                    y = i // width
>                   assert 0, (
                        f'Pixel ({x}, {y}) in {name}: '
                        f'expected rgba{expected}, got rgba{value}')
E                   AssertionError: Pixel (0, 0) in linear_gradients_12: expected rgba(0, 0, 255), got rgba(255, 255, 255)
/builddir/build/BUILD/weasyprint-57.0/tests/draw/__init__.py:104: AssertionError
------------------------------ Captured log call -------------------------------
...
=============================== warnings summary ===============================
...
=========================== short test summary info ============================
FAILED tests/draw/test_gradient.py::test_linear_gradients_5 - AssertionError:...
FAILED tests/draw/test_gradient.py::test_linear_gradients_12 - AssertionError...
====== 2 failed, 1870 passed, 41 xfailed, 8 warnings in 90.75s (0:01:30) =======

I guess next thing is that you are asking me for the PDF generated in the test as you did previously? I can do that but not today.

[liZe]

I think that these bugs are caused by Ghostscript’s bug 705225. They appear only with Ghostscript 9.56, but not with 9.55 or 10.0.

[FelixSchwarz]

Ah, I see. As you provided a very specific reference, Fedora has now a PR to cherry-pick that patch to its ghostscript package until ghostscript 10.0 is added Fedora.