How to load data from a file, for a unit test, in python?

Question

I've written a specialized HTML parser, that I want to unit test with a couple of sample webpages I've downloaded.

In Java, I've used class resources, to load data into unit tests, without having to rely on them being at a particular path on the file system. Is there a way to do this in Python?

I found the doctest.testfile() function, but that appears to be specific to doctests. I'd like to just get a file handle, to a particular HTML file, which is relative to the current module.

Thanks in advance for any suggestions!

Anto · Accepted Answer · 2016-09-22 09:13:51Z

89

To load data from a file in a unittest, if the testdata is on the same dir as unittests, one solution :

TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), 'testdata.html')


class MyTest(unittest.TestCase)

   def setUp(self):
       self.testdata = open(TESTDATA_FILENAME).read()

   def test_something(self):
       ....

edited Sep 22, 2016 at 9:13

Anto

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answered Nov 8, 2011 at 11:36

Ferran

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2 Comments

Kim Over a year ago

Using the 'new' python pathlib this command becomes: TEST_FILE = pathlib.Path(__file__).parent.joinpath("testdata.html") and then TEST_FILE.open(). Remember to import pathlib and please note the suggestion in the answer from @LeilaHC to properly close the testfile again, e.g. in the tearDown method.

kojiro Over a year ago

pkg_resources is a tool that comes with setuptools. If a package is installed, even with just pip install -e or ./setup.py develop, then pkg_resources can find resource files just by knowing __name__.

Leila Hadj-Chikh · Accepted Answer · 2019-01-30 15:43:57Z

25

This is based on Ferran's answer, but it closes the file during MyTest.tearDown() to avoid 'ResourceWarning: unclosed file':

TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), 'testdata.html')


class MyTest(unittest.TestCase)

   def setUp(self):
       self.testfile = open(TESTDATA_FILENAME)
       self.testdata = self.testfile.read()

   def tearDown(self):
       self.testfile.close()

   def test_something(self):
       ....

answered Jan 30, 2019 at 15:43

Leila Hadj-Chikh

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1 Comment

Splendor Over a year ago

For visibility, it might be better to edit Ferran's answer with your addition.

Christian Alis · Accepted Answer · 2011-11-08 10:26:52Z

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You can also use a StringIO or cStringIO to simulate a string containing your file's contents as a file.

answered Nov 8, 2011 at 10:26

Christian Alis

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1 Comment

cberner Over a year ago

Ya, I thought of that, but it would require that I put all the HTML into a python file as a string, which I don't like as it's > 3k lines long

Community · Accepted Answer · 2017-05-23 12:02:34Z

1

I guess your task boils down to what's given here to get the current file. Then extend that path by the path to you HTML file and open it.

edited May 23, 2017 at 12:02

CommunityBot

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answered Nov 8, 2011 at 9:50

Johannes Charra

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