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import io
import pkgutil
import pytest
import altair as alt
from altair.utils.execeval import eval_block
from tests import examples_arguments_syntax
from tests import examples_methods_syntax
try:
import altair_saver # noqa: F401
except ImportError:
altair_saver = None
try:
import vl_convert as vlc # noqa: F401
except ImportError:
vlc = None
def iter_examples_filenames(syntax_module):
for _importer, modname, ispkg in pkgutil.iter_modules(syntax_module.__path__):
if ispkg or modname.startswith("_"):
continue
yield modname + ".py"
@pytest.mark.parametrize(
"syntax_module", [examples_arguments_syntax, examples_methods_syntax]
)
def test_render_examples_to_chart(syntax_module):
for filename in iter_examples_filenames(syntax_module):
source = pkgutil.get_data(syntax_module.__name__, filename)
chart = eval_block(source)
if chart is None:
raise ValueError(
f"Example file {filename} should define chart in its final "
"statement."
)
try:
assert isinstance(chart.to_dict(), dict)
except Exception as err:
raise AssertionError(
f"Example file {filename} raised an exception when "
f"converting to a dict: {err}"
) from err
@pytest.mark.parametrize(
"syntax_module", [examples_arguments_syntax, examples_methods_syntax]
)
def test_from_and_to_json_roundtrip(syntax_module):
"""Tests if the to_json and from_json (and by extension to_dict and from_dict)
work for all examples in the Example Gallery.
"""
for filename in iter_examples_filenames(syntax_module):
source = pkgutil.get_data(syntax_module.__name__, filename)
chart = eval_block(source)
if chart is None:
raise ValueError(
f"Example file {filename} should define chart in its final "
"statement."
)
try:
first_json = chart.to_json()
reconstructed_chart = alt.Chart.from_json(first_json)
# As the chart objects are not
# necessarily the same - they could use different objects to encode the same
# information - we do not test for equality of the chart objects, but rather
# for equality of the json strings.
second_json = reconstructed_chart.to_json()
assert first_json == second_json
except Exception as err:
raise AssertionError(
f"Example file {filename} raised an exception when "
f"doing a json conversion roundtrip: {err}"
) from err
# We do not apply the save_engine mark to this test. This mark is used in
# the build GitHub Action workflow to select the tests which should be rerun
# with some of the saving engines uninstalled. This would not make sense for this test
# as here it is only interesting to run it with all saving engines installed.
# Furthermore, the runtime of this test is rather long.
@pytest.mark.parametrize("engine", ["vl-convert", "altair_saver"])
@pytest.mark.parametrize(
"syntax_module", [examples_arguments_syntax, examples_methods_syntax]
)
def test_render_examples_to_png(engine, syntax_module):
for filename in iter_examples_filenames(syntax_module):
if engine == "vl-convert" and vlc is None:
pytest.skip("vl_convert not importable; cannot run mimebundle tests")
elif engine == "altair_saver":
if altair_saver is None:
pytest.skip("altair_saver not importable; cannot run png tests")
if "png" not in altair_saver.available_formats("vega-lite"):
pytest.skip("altair_saver not configured to save to png")
source = pkgutil.get_data(syntax_module.__name__, filename)
chart = eval_block(source)
out = io.BytesIO()
chart.save(out, format="png", engine=engine)
assert out.getvalue().startswith(b"\x89PNG")
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