在 python 中对实现 ImageDraw 的方法进行单元测试
Carrying out unit testing in python on a method that implements ImageDraw
我目前正在尝试使用 pytest 模块为我正在处理的项目创建单元测试。我正在尝试测试基于一组像素绘制椭圆的 'add_point' 方法。我想要做的是检查 'draw' 以确保已成功创建椭圆。不幸的是，我不知道该怎么做，所以我们将不胜感激。到目前为止，这是我的代码：
(A) TheSlicePreviewMaker.py
import os, Image, ImageDraw, ImageFont
from json_importer import json_importer
class SlicePreviewer(object):
def __init__(self):
self.screen_size = (470, 470)
self.background_colour = (86,0,255)
self.platform_fill_colour = (100, 100, 100)
self.platform_outline_colour = (0, 0, 0)
self.platform_window = (0,0,469,469)
self.point_colour = (0,0,255)
self.config_object = json_importer("ConfigFile.txt")
self.image = None
def initialise_image(self):
self.image = Image.new('RGB',self.screen_size,self.background_colour)
draw = ImageDraw.Draw(self.image)
draw.rectangle(self.platform_window,outline=self.platform_outline_colour,fill=self.platform_fill_colour)
del draw
def add_point(self, px, py):
x1 = px - 1
y1 = py - 1
x2 = px + 1
y2 = py + 1
draw = ImageDraw.Draw(self.image)
draw.ellipse((x1,y1,x2,y2),outline=self.point_colour,fill=self.point_colour)
return draw #del draw
def save_image(self, file_name):
self.image.save(file_name, "BMP")
(B) test_TheSlicePreviewMaker.py
from TheSlicePreviewMaker import SlicePreviewer
slice_preview = SlicePreviewer()
class TestSlicePreviewer:
def test_init(self):
'''check that the config file object has been created on init'''
assert slice_preview.config_object != None
def test_initialise_image(self):
'''verify if the image has been successfully initialised'''
assert slice_preview.image.mode == 'RGB'
def test_add_point(self):
'''has the point been drawn successfully?'''
draw = slice_preview.add_point(196,273)
assert something
import pytest
if __name__ == '__main__':
pytest.main("--capture=sys -v")
SN：我已经运行TheSlicePreviewMaker.py分别检查了它生成的位图文件，所以我知道代码是有效的。我想要实现的是对此进行单元测试，这样我就不必每次都去检查位图了。
一种方法是手动检查生成的图像，如果你觉得没问题，将其保存在测试旁边并使用图像差异算法（例如 ImageChops.difference）获得一个阈值，你可以用于确保未来的测试 运行 仍在绘制相同的图像。
例如：
# contents of conftest.py
from PIL import ImageChops, ImageDraw, Image
import pytest
import os
import py.path
import math
import operator
def rms_diff(im1, im2):
"""Calculate the root-mean-square difference between two images
Taken from: http://snipplr.com/view/757/compare-two-pil-images-in-python/
"""
h1 = im1.histogram()
h2 = im2.histogram()
def mean_sqr(a,b):
if not a:
a = 0.0
if not b:
b = 0.0
return (a-b)**2
return math.sqrt(reduce(operator.add, map(mean_sqr, h1, h2))/(im1.size[0]*im1.size[1]))
class ImageDiff:
"""Fixture used to make sure code that generates images continues to do so
by checking the difference of the genereated image against known good versions.
"""
def __init__(self, request):
self.directory = py.path.local(request.node.fspath.dirname) / request.node.fspath.purebasename
self.expected_name = (request.node.name + '.png')
self.expected_filename = self.directory / self.expected_name
def check(self, im, max_threshold=0.0):
__tracebackhide__ = True
local = py.path.local(os.getcwd()) / self.expected_name
if not self.expected_filename.check(file=1):
msg = '\nExpecting image at %s, but it does not exist.\n'
msg += '-> Generating here: %s'
im.save(str(local))
pytest.fail(msg % (self.expected_filename, local))
else:
expected = Image.open(str(self.expected_filename))
rms_value = rms_diff(im, expected)
if rms_value > max_threshold:
im.save(str(local))
msg = '\nrms_value %s > max_threshold of %s.\n'
msg += 'Obtained image saved at %s'
pytest.fail(msg % (rms_value, max_threshold, str(local)))
@pytest.fixture
def image_diff(request):
return ImageDiff(request)
现在您可以在测试中使用 image_diff 夹具。例如：
def create_image():
""" dummy code that generates an image, simulating some actual code """
im = Image.new('RGB', (100, 100), (0, 0, 0))
draw = ImageDraw.Draw(im)
draw.ellipse((10, 10, 90, 90), outline=(0, 0, 255),
fill=(255, 255, 255))
return im
def test_generated_image(image_diff):
im = create_image()
image_diff.check(im)
第一次 运行 此测试将失败并显示以下输出：
================================== FAILURES ===================================
____________________________ test_generated_image _____________________________
image_diff = <test_foo.ImageDiff instance at 0x029ED530>
def test_generated_image(image_diff):
im = create_image()
> image_diff.check(im)
E Failed:
E Expecting image at X:\temp\sandbox\img-diff\test_foo\test_generated_image.png, but it does not exist.
E -> Generating here: X:\temp\sandbox\img-diff\test_generated_image.png
然后您可以手动检查图像，如果一切正常，请将其移动到与测试文件同名的目录中，以测试名称为文件名加上“.png”扩展名。从现在开始，每当测试 运行s 时，它都会检查图像是否在可接受的范围内相似。
假设您更改代码并生成略有不同的图像，测试现在将像这样失败：
================================== FAILURES ===================================
____________________________ test_generated_image _____________________________
image_diff = <test_foo.ImageDiff instance at 0x02A4B788>
def test_generated_image(image_diff):
im = create_image()
> image_diff.check(im)
E Failed:
E rms_value 2.52 > max_threshold of 0.0.
E Obtained image saved at X:\temp\sandbox\img-diff\test_generated_image.png
test_foo.py:63: Failed
========================== 1 failed in 0.03 seconds ===========================
代码需要一些改进，但应该是一个好的开始。您可以找到此代码的一个版本 here.
干杯，
我目前正在尝试使用 pytest 模块为我正在处理的项目创建单元测试。我正在尝试测试基于一组像素绘制椭圆的 'add_point' 方法。我想要做的是检查 'draw' 以确保已成功创建椭圆。不幸的是，我不知道该怎么做，所以我们将不胜感激。到目前为止，这是我的代码：
(A) TheSlicePreviewMaker.py
import os, Image, ImageDraw, ImageFont
from json_importer import json_importer
class SlicePreviewer(object):
def __init__(self):
self.screen_size = (470, 470)
self.background_colour = (86,0,255)
self.platform_fill_colour = (100, 100, 100)
self.platform_outline_colour = (0, 0, 0)
self.platform_window = (0,0,469,469)
self.point_colour = (0,0,255)
self.config_object = json_importer("ConfigFile.txt")
self.image = None
def initialise_image(self):
self.image = Image.new('RGB',self.screen_size,self.background_colour)
draw = ImageDraw.Draw(self.image)
draw.rectangle(self.platform_window,outline=self.platform_outline_colour,fill=self.platform_fill_colour)
del draw
def add_point(self, px, py):
x1 = px - 1
y1 = py - 1
x2 = px + 1
y2 = py + 1
draw = ImageDraw.Draw(self.image)
draw.ellipse((x1,y1,x2,y2),outline=self.point_colour,fill=self.point_colour)
return draw #del draw
def save_image(self, file_name):
self.image.save(file_name, "BMP")
(B) test_TheSlicePreviewMaker.py
from TheSlicePreviewMaker import SlicePreviewer
slice_preview = SlicePreviewer()
class TestSlicePreviewer:
def test_init(self):
'''check that the config file object has been created on init'''
assert slice_preview.config_object != None
def test_initialise_image(self):
'''verify if the image has been successfully initialised'''
assert slice_preview.image.mode == 'RGB'
def test_add_point(self):
'''has the point been drawn successfully?'''
draw = slice_preview.add_point(196,273)
assert something
import pytest
if __name__ == '__main__':
pytest.main("--capture=sys -v")
SN：我已经运行TheSlicePreviewMaker.py分别检查了它生成的位图文件，所以我知道代码是有效的。我想要实现的是对此进行单元测试，这样我就不必每次都去检查位图了。
一种方法是手动检查生成的图像，如果你觉得没问题，将其保存在测试旁边并使用图像差异算法（例如 ImageChops.difference）获得一个阈值，你可以用于确保未来的测试 运行 仍在绘制相同的图像。
例如：
# contents of conftest.py
from PIL import ImageChops, ImageDraw, Image
import pytest
import os
import py.path
import math
import operator
def rms_diff(im1, im2):
"""Calculate the root-mean-square difference between two images
Taken from: http://snipplr.com/view/757/compare-two-pil-images-in-python/
"""
h1 = im1.histogram()
h2 = im2.histogram()
def mean_sqr(a,b):
if not a:
a = 0.0
if not b:
b = 0.0
return (a-b)**2
return math.sqrt(reduce(operator.add, map(mean_sqr, h1, h2))/(im1.size[0]*im1.size[1]))
class ImageDiff:
"""Fixture used to make sure code that generates images continues to do so
by checking the difference of the genereated image against known good versions.
"""
def __init__(self, request):
self.directory = py.path.local(request.node.fspath.dirname) / request.node.fspath.purebasename
self.expected_name = (request.node.name + '.png')
self.expected_filename = self.directory / self.expected_name
def check(self, im, max_threshold=0.0):
__tracebackhide__ = True
local = py.path.local(os.getcwd()) / self.expected_name
if not self.expected_filename.check(file=1):
msg = '\nExpecting image at %s, but it does not exist.\n'
msg += '-> Generating here: %s'
im.save(str(local))
pytest.fail(msg % (self.expected_filename, local))
else:
expected = Image.open(str(self.expected_filename))
rms_value = rms_diff(im, expected)
if rms_value > max_threshold:
im.save(str(local))
msg = '\nrms_value %s > max_threshold of %s.\n'
msg += 'Obtained image saved at %s'
pytest.fail(msg % (rms_value, max_threshold, str(local)))
@pytest.fixture
def image_diff(request):
return ImageDiff(request)
现在您可以在测试中使用 image_diff 夹具。例如：
def create_image():
""" dummy code that generates an image, simulating some actual code """
im = Image.new('RGB', (100, 100), (0, 0, 0))
draw = ImageDraw.Draw(im)
draw.ellipse((10, 10, 90, 90), outline=(0, 0, 255),
fill=(255, 255, 255))
return im
def test_generated_image(image_diff):
im = create_image()
image_diff.check(im)
第一次 运行 此测试将失败并显示以下输出：
================================== FAILURES ===================================
____________________________ test_generated_image _____________________________
image_diff = <test_foo.ImageDiff instance at 0x029ED530>
def test_generated_image(image_diff):
im = create_image()
> image_diff.check(im)
E Failed:
E Expecting image at X:\temp\sandbox\img-diff\test_foo\test_generated_image.png, but it does not exist.
E -> Generating here: X:\temp\sandbox\img-diff\test_generated_image.png
然后您可以手动检查图像，如果一切正常，请将其移动到与测试文件同名的目录中，以测试名称为文件名加上“.png”扩展名。从现在开始，每当测试 运行s 时，它都会检查图像是否在可接受的范围内相似。
假设您更改代码并生成略有不同的图像，测试现在将像这样失败：
================================== FAILURES ===================================
____________________________ test_generated_image _____________________________
image_diff = <test_foo.ImageDiff instance at 0x02A4B788>
def test_generated_image(image_diff):
im = create_image()
> image_diff.check(im)
E Failed:
E rms_value 2.52 > max_threshold of 0.0.
E Obtained image saved at X:\temp\sandbox\img-diff\test_generated_image.png
test_foo.py:63: Failed
========================== 1 failed in 0.03 seconds ===========================
代码需要一些改进，但应该是一个好的开始。您可以找到此代码的一个版本 here.
干杯，