A simple Python script used for comparing two folders containing screenshots after an Espresso/Spoon run. One folder contains your base screenshots the other folder your newly screenshots. Use this as your last regression resort to see if Espresso overlooked something.

image-comparator

#!/usr/bin/python
import glob
import os
import sys
from subprocess import Popen, PIPE

# Script that will compare screenshots to a set of previous screenshots
# first arg: full path to base screenshots
# second arg: full path to spoon output dir

# Presumes you have `ImageMagick` compare tool on your path

# Exit codes
# 1: Supplied arguments are not directories
# 2: Folders have different amounts of files (for comparison we ask them to be the same)

old_folder_path = "old/"  # sys.argv[1]
spoon_path = "new/"  # sys.argv[2]

# Tolerance allowance between screenshots
FUZZINESS_LEVEL = "5%"
# Folder where different images will be stored
DIFF_SAVE_IMG_FOLDER = "dff/"


# { "testClass$$methodName" : "fileName" }
def get_screenshot_dictionary(path):
    local_dict = dict()
    for pngFile in glob.iglob(os.path.join(path, "*", "*", "*.png")):
        class_name_method_name_file_name = [path_piece for path_piece in pngFile.split("/")[-3:]]
        key = "%s$$%s" % (class_name_method_name_file_name[0], class_name_method_name_file_name[1])
        local_dict[key] = class_name_method_name_file_name[2]

    return local_dict


def check_if_argument_is_directory():
    return os.path.isdir(old_folder_path) and os.path.isdir(spoon_path)


def has_same_amount_files(old_dict, new_dict):
    return len(old_dict) == len(new_dict)


def get_file_name_for(path, dic, class_name_with_method_name):
    class_name, method_name = class_name_with_method_name.split("$$")
    abs_path = '/'.join([path, class_name, method_name, dic[class_name_with_method_name]])
    full_path = "%s/%s" % (os.path.dirname(os.path.abspath(__file__)), abs_path)
    return full_path


def do_image_diffing(old_dict, new_dict):
    make_folder(DIFF_SAVE_IMG_FOLDER)

    for classNameWithMethodName, fileName in old_dict.items():
        if classNameWithMethodName in new_dict:
            old_file = get_file_name_for(old_folder_path, old_dict, classNameWithMethodName)
            new_file = get_file_name_for(spoon_path, new_dict, classNameWithMethodName)
            diff_file = "%s%s" % (DIFF_SAVE_IMG_FOLDER, classNameWithMethodName)

            if is_a_file(old_file) and is_a_file(new_file):
                diff = Popen(
                    ['compare',
                     '-highlight-color', 'red',
                     '-compose', 'src',
                     '-channel', 'RGBA',
                     '-metric', 'PSNR',
                     '-fuzz', '100%',
                     old_file, new_file, diff_file], stdin=PIPE, stdout=PIPE, stderr=PIPE).communicate()[1]

                print diff
                if diff == "inf\n":
                    remove_file(diff_file)


# <editor-fold desc="Helper functions">

def is_a_file(full_file_path):
    return os.path.isfile(full_file_path)


def remove_file(full_file_path):
    os.remove(full_file_path)


def make_folder(with_name):
    if not os.path.exists(with_name):
        os.makedirs(with_name)


# </editor-fold>

if __name__ == "__main__":
    if check_if_argument_is_directory():
        old_screenshot_dict = get_screenshot_dictionary(old_folder_path)
        new_screenshot_dict = get_screenshot_dictionary(spoon_path)
        if has_same_amount_files(old_screenshot_dict, new_screenshot_dict):
            do_image_diffing(old_screenshot_dict, new_screenshot_dict)
        else:
            sys.exit(2)
    else:
        sys.exit(1)