def compareScreenshot(self, element_or_selector, filename, threshold=0.1):
"""
Assert that a screenshot of an element is the same as a screenshot on disk,
within a given threshold.
:param element_or_selector:
Either a CSS selector as a string or a
:py:class:`~needle.driver.NeedleWebElement` object that represents
the element to capture.
:param name:
A name for the screenshot, which will be appended with ``.png``.
:param threshold:
The threshold for triggering a test failure.
"""
if not isinstance(filename, basestring):
raise NotImplementedError
baseline_file = os.path.join(self.baseline_directory, '%s.png' % filename)
output_file = os.path.join(self.output_directory, '%s.png' % filename)
if self.capture and os.path.exists(baseline_file):
self.skipTest('Not capturing %s, image already exists. If you '
'want to capture this element again, delete %s'
% (filename, baseline_file))
yield
if not isinstance(element_or_selector, NeedleWebElement):
element = self.driver.find_element_by_css_selector(element_or_selector)
else:
element = element_or_selector
if self.capture:
element.get_screenshot().save(baseline_file)
return
else:
screenshot = element.get_screenshot()
screenshot.save(output_file)
if self.use_perceptualdiff:
diff_filename = output_file.replace(".png", ".diff.ppm")
try:
# BUG: figure out how best to convert threshold distances to pixel counts
subprocess.check_call(["perceptualdiff", "-output", diff_filename,
baseline_file, output_file])
except subprocess.CalledProcessError:
raise AssertionError("The saved screenshot for '%s' did not match "
"the screenshot captured: see %s"
% (filename, diff_filename))
else:
baseline_image = Image.open(baseline_file)
diff = ImageDiff(screenshot, baseline_image)
distance = abs(diff.get_distance())
if distance > threshold:
raise AssertionError("The saved screenshot for '%s' did not match "
"the screenshot captured (by a distance of %.2f)"
% (filename, distance))
def assertScreenshot(self, element, name, threshold=0.1):
"""
Assert that a screenshot of an element is the same as a screenshot on disk,
within a given threshold.
:param element: Either a CSS selector as a string or a
:py:class:`~needle.driver.NeedleWebElement` object that
represents the element to capture.
:param name: A name for the screenshot, which will be appended with
``.png``.
:param threshold: The threshold for triggering a test failure.
"""
if isinstance(element, basestring):
element = self.driver.find_element_by_css_selector(element)
if isinstance(name, basestring):
filename = os.path.join(
os.path.dirname(_object_filename(self)),
'%s.png' % name
)
else:
# names can be filehandles for testing. This sucks - we
# should write out files to their correct location
filename = name
if self.capture:
if os.path.exists(filename):
self.skipTest('Not capturing %s, image already exists. If you '
'want to capture this element again, delete %s'
% (name, filename))
element.get_screenshot().save(filename)
else:
image = Image.open(filename)
# now take another screenshot and re open it (yea i know) but there were issues wth colours
screenshot_filename = filename.replace('.png','-compare.png')
screenshot = element.get_screenshot().save(screenshot_filename)
screenshot = Image.open(screenshot_filename)
diff = ImageDiff(screenshot, image)
distance = abs(diff.get_distance())
if distance > threshold:
raise AssertionError("The saved screenshot for '%s' did not match "
"the screenshot captured (by a distance of %.2f)"
% (name, distance))
def test_nrmsd_all_channels(self):
diff = ImageDiff(self.get_white_image(), self.get_black_image())
self.assertEqual(diff.get_nrmsd(), 1)
def test_distance_half_filled(self):
diff = ImageDiff(self.get_black_image(), self.get_half_filled_image())
self.assertAlmostEqual(diff.get_distance(), 10000.0 / 2, delta=0.001)
def test_distance_one_channel(self):
diff = ImageDiff(self.get_image((255, 0, 0)), self.get_black_image())
self.assertAlmostEqual(diff.get_distance(), 10000.0 / 3, delta=0.001)
def test_distance_all_channels(self):
diff = ImageDiff(self.get_white_image(), self.get_black_image())
self.assertAlmostEqual(diff.get_distance(), 100 * 100, delta=0.001)
def test_nrmsd_half_filled(self):
diff = ImageDiff(self.get_black_image(), self.get_half_filled_image())
self.assertEqual(diff.get_nrmsd(), math.sqrt(0.5))
def test_nrmsd_one_channel(self):
diff = ImageDiff(self.get_image((255, 0, 0)), self.get_black_image())
self.assertEqual(diff.get_nrmsd(), math.sqrt(1.0 / 3))
def compareScreenshot(self, element_or_selector, filename, threshold=0.1):
"""
Assert that a screenshot of an element is the same as a screenshot on disk,
within a given threshold.
:param element_or_selector:
Either a CSS selector as a string or a
:py:class:`~needle.driver.NeedleWebElement` object that represents
the element to capture.
:param name:
A name for the screenshot, which will be appended with ``.png``.
:param threshold:
The threshold for triggering a test failure.
"""
if not isinstance(filename, basestring):
raise NotImplementedError
baseline_file = os.path.join(self.baseline_directory,
'%s.png' % filename)
output_file = os.path.join(self.output_directory, '%s.png' % filename)
if self.capture and os.path.exists(baseline_file):
self.skipTest('Not capturing %s, image already exists. If you '
'want to capture this element again, delete %s' %
(filename, baseline_file))
yield
if not isinstance(element_or_selector, NeedleWebElement):
element = self.driver.find_element_by_css_selector(
element_or_selector)
else:
element = element_or_selector
if self.capture:
element.get_screenshot().save(baseline_file)
return
else:
screenshot = element.get_screenshot()
screenshot.save(output_file)
if self.use_perceptualdiff:
diff_filename = output_file.replace(".png", ".diff.ppm")
try:
# BUG: figure out how best to convert threshold distances to pixel counts
subprocess.check_call([
"perceptualdiff", "-output", diff_filename,
baseline_file, output_file
])
except subprocess.CalledProcessError:
raise AssertionError(
"The saved screenshot for '%s' did not match "
"the screenshot captured: see %s" %
(filename, diff_filename))
else:
baseline_image = Image.open(baseline_file)
diff = ImageDiff(screenshot, baseline_image)
distance = abs(diff.get_distance())
if distance > threshold:
raise AssertionError(
"The saved screenshot for '%s' did not match "
"the screenshot captured (by a distance of %.2f)" %
(filename, distance))
def compareScreenshot(self, element_or_selector, file, threshold=0.1):
"""
Assert that a screenshot of an element is the same as a screenshot on disk,
within a given threshold.
:param element_or_selector:
Either a CSS selector as a string or a
:py:class:`~needle.driver.NeedleWebElement` object that represents
the element to capture.
:param file:
If a string, then assumed to be the filename for the screenshot,
which will be appended with ``.png``. Otherwise assumed to be
a file object for the baseline image.
:param threshold:
The threshold for triggering a test failure.
"""
yield # To allow using this method as a context manager
if not isinstance(element_or_selector, NeedleWebElement):
element = self.driver.find_element_by_css_selector(element_or_selector)
else:
element = element_or_selector
if isinstance(file, basestring):
baseline_file = os.path.join(self.baseline_directory, '%s.png' % file)
output_file = os.path.join(self.output_directory, '%s.png' % file)
if self.capture and os.path.exists(baseline_file):
self.skipTest('Not capturing %s, image already exists. If you '
'want to capture this element again, delete %s'
% (file, baseline_file))
if self.capture:
element.get_screenshot().save(baseline_file)
return
else:
baseline_image = Image.open(baseline_file)
fresh_screenshot = element.get_screenshot()
fresh_screenshot.save(output_file)
if self.use_perceptualdiff:
# TODO: figure out how best to convert threshold distances to pixel counts
diff_ppm = output_file.replace(".png", ".diff.ppm")
cmd = "%s -output %s %s %s" % (self.perceptualdiff_path, diff_ppm, baseline_file, output_file)
process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
perceptualdiff_stdout, _ = process.communicate()
if process.returncode == 0:
# No differences found
return
else:
if os.path.exists(diff_ppm):
if self.perceptualdiff_output_png:
# Convert the .ppm output to .png
diff_png = diff_ppm.replace("diff.ppm", "diff.png")
Image.open(diff_ppm).save(diff_png)
os.remove(diff_ppm)
diff_file_msg = ' (See %s)' % diff_png
else:
diff_file_msg = ' (See %s)' % diff_ppm
else:
diff_file_msg = ''
raise AssertionError("The saved screenshot for '%s' did not match "
"the screenshot captured%s:\n%s"
% (file, diff_file_msg, perceptualdiff_stdout))
else:
baseline_image = Image.open(file).convert('RGB')
fresh_screenshot = element.get_screenshot()
diff = ImageDiff(fresh_screenshot, baseline_image)
distance = abs(diff.get_distance())
if distance > threshold:
raise AssertionError("The given screenshot did not match the "
"screenshot captured (by a distance of %.2f)"
% distance)
