torchtestcase

torch-test-case

Using Python's unittest package turns out to be cumbersome when we are working with PyTorch and need to write assertions that include tensors, parameters, and so forth. The main reason for this is that PyTorch tensors are compared element-wise by default, which is why assertions provided by the class unittest.TestCase do not work out-of-the-box. A possible workaround is to use TestCase.assertTrue for any assertion that we need to make, yet this commonly leads to convoluted code that is hard to read and maintain.

The module torchtestcase defines the class TorchTestCase, which extends unittest.TestCase such that many assertions support instances of various PyTorch classes.

Updates:

• Version 2018.1 has been released, and supports PyTorch 0.4 now.
• Version 2018.2 has been released, and introduces the specification of a permissible deviation for tensor equality assertions.

Installation

This module can be installed from PyPI:

pip install torchtestcase

PyTorch Assertions

This section describes those assertions provided by the class TorchTestCase that support PyTorch. If you are not familiar with the package unittest, then read about it first here.

Notice: With the release of PyTorch 0.4.0, tensors and variables have been merged, which means that Variables are treated just like any other tensors, and thus there is no need to make use of the class torch.autograd.Variable anymore. Accordingly, assertions for Variables in particular have been removed in version 2018.1 of torchtestcase.

1. Equality Assertions

(assertEqual, assertNotEqual)

Equality assertions support objects that are any kind of PyTorch tensors as well as instances of torch.nn.Parameter and torch.nn.utils.rnn.PackedSequence. Notice, however, that an AssertionError is raised if the compared objects are instances of different types:

self.assertEqual(torch.zeros(4), nn.Parameter(torch.zeros(4)))  # -> AssertionError

Occasionally, we do not expect two tensors to match each other exactly, which is the case if we anticipate numerical instabilities, for example. For any such case, TorchTestCase provides the possibility to specify a certain tolerance:

self.eps = 0.001                                          # specify tolerance for equality assertions
self.assertEqual(torch.zeros(3), 0.001 * torch.ones(3))   # -> no AssertionError
self.assertEqual(torch.zeros(3), 0.0011 * torch.ones(3))  # -> AssertionError

Notice that a specified tolerance is taken into account for equality assertions between two tensors only.

2. Order Assertions

(assertGreater, assertGreaterEqual, assertLess, assertLessEqual)

In general, order assertions are assumed to be fulfilled if they hold element-wise. For example:

x = torch.FloatTensor([0, 0, 1])
y = torch.FloatTensor([1, 1, 1])
self.assertLessEqual(x, y)  # -> no AssertionError
self.assertLess(x, y)       # -> AssertionError

In addition, it is possible to compare tensors or Parameters to a number, in which case each element of the considered data tensor is compared to the same. For example, if we want to ensure that every element of a tensor lies in the unit interval, then we may use the following assertions:

self.assertGreaterEqual(some_tensor, 0)
self.assertLessEqual(some_tensor, 1)

When we make order assertions, then we usually do not care about the actual types of the objects involved. Therefore, it is possible to compare different kinds of tensors with each other as well as with Parameters:

self.assertLess(torch.zeros(3), nn.Parameter(torch.ones(3)))  # -> no AssertionError