Capturing Human Intelligence - ApprovalTests is an open source assertion/verification library to aid testing.
approvaltests
is the ApprovalTests port for Python.
For more information see: www.approvaltests.com.
##What can I use ApprovalTests for?
You can use ApprovalTests to verify objects that require more than a simple assert including long strings, large arrays,
and complex hash structures and objects. ApprovalTests really shines when you need a more granular look at the test
failure. Sometimes, trying to find a small difference in a long string printed to STDOUT is just too hard!
ApprovalTests solves this problem by providing reporters which let you view the test results in one of many popular diff
utilities.
##SETUP
From pypi:
pip install approvaltests
##GETTING STARTED
import unittest
from approvaltests.Approvals import verify
from approvaltests.GenericDiffReporterFactory import GenericDiffReporterFactory
class GettingStartedTest(unittest.TestCase):
def setUp(self):
self.reporter = GenericDiffReporterFactory().get_first_working()
def test_simple(self):
verify('Hello', self.reporter)
if __name__ == "__main__":
unittest.main()
Approvals work by comparing the test results to a golden master. If no golden master exists you can create a snapshot
of the current test results and use that as the golden master. The reporter helps you manage the golden master.
Whenever your current results differ from the golden master, the reporter will launch an external application and then
change some part of the system. Either you will update the master because you expected the changes and they are good,
or you will go back to your code and update or roll back your changes to get your results back in line with the
golden master.
The reporter is used both to alert you to changes in your test output, and to provide a tool to update the golden
master. So, diff and merge utilities make very good reporters. Approvals come with a few reporters configured,
supporting Linux, Mac OSX, and Windows. In the example shown above, we use the GenericDiffReporterFactory
to find
and select the first diff utility that exists on our system. Later, we pass that reporter to the verify method so that
it can be used if the test fails.
You don't have to do it this way. You can request a specific reporter from the factory using the get
method
class GettingStartedTest(unittest.TestCase):
def setUp(self):
self.factory = GenericDiffReporterFactory()
def test_simple(self):
verify('Hello', self.factory.get('BeyondCompare4'))
Or you can build your own GenericDiffReporter on the fly
class GettingStartedTest(unittest.TestCase):
def test_simple(self):
verify('Hello', GenericDiffReporter(('Custom', 'C:/my/favorite/diff/utility.exe')))
As long as C:/my/favorite/diff/utility.exe
can be invoked from the command line using the format utility.exe file1 file2
then it will be compatible with GenericDiffReporter. Otherwise you will have to derive your own reporter, which
we won't cover here.
To wrap up things up, I should note that you can completely replace the collection of reporters known to the reporter factory by writing your own JSON file and loading it.
For example if you had C:/myreporters.json
[
[
"BeyondCompare4",
"C:/Program Files (x86)/Beyond Compare 4/BCompare.exe"
],
[
"WinMerge",
"C:/Program Files (x86)/WinMerge/WinMergeU.exe"
],
[
"Tortoise",
"C:/Program Files (x86)/TortoiseSVN/bin/tortoisemerge.exe"
]
]
You could then use that file by loading it into the factory:
import unittest
from approvaltests.Approvals import verify
from approvaltests.GenericDiffReporterFactory import GenericDiffReporterFactory
class GettingStartedTest(unittest.TestCase):
def setUp(self):
factory = GenericDiffReporterFactory()
factory.load('C:/myreporters.json')
self.reporter = factory.get_first_working()
def test_simple(self):
verify('Hello', self.reporter)
if __name__ == "__main__":
unittest.main()
Of course, if you have some interesting new reporters in myreporters.json
then please consider updating the
reporters.json
file that ships with Approvals and submitting a pull request.
##SUPPORT AND DOCUMENTATION
-
ApprovalTests Homepage: http://www.approvaltests.com