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import io
from functools import partial
from pytest_regressions.testing import check_regression_fixture_workflow
def test_image_regression(image_regression, datadir):
import matplotlib
# this ensures matplot lib does not use a GUI backend (such as Tk)
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import numpy as np
t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2 * np.pi * t)
fig, ax = plt.subplots()
ax.plot(t, s)
ax.set(
xlabel="time (s)",
ylabel="voltage (mV)",
title="About as simple as it gets, folks",
)
ax.grid()
image_filename = datadir / "test.png"
fig.savefig(str(image_filename))
image_regression.check(image_filename.read_bytes(), diff_threshold=1.0)
def test_image_regression_workflow(pytester, monkeypatch, datadir):
import sys
from PIL import Image
def get_image(color):
f = io.BytesIO()
img = Image.new("RGB", (100, 100), color)
img.save(f, "PNG")
return f.getvalue()
monkeypatch.setattr(sys, "get_image", partial(get_image, "white"), raising=False)
source = """
import sys
def test_1(image_regression):
contents = sys.get_image()
image_regression.check(contents)
"""
def get_file_contents():
fn = pytester.path / "test_file" / "test_1.png"
assert fn.is_file()
return fn.read_bytes()
check_regression_fixture_workflow(
pytester,
source,
data_getter=get_file_contents,
data_modifier=lambda: monkeypatch.setattr(
sys, "get_image", partial(get_image, "black"), raising=False
),
expected_data_1=get_image("white"),
expected_data_2=get_image("black"),
)
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