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+# Unit and integration testing
+
+## Running the tests
+The unit and integration tests can be executed by invoking `tox` from any
+path under the project directory.
+
+```
+$ tox
+```
+
+Or by invoking `aggregate_tests.py` from the
+[tests](https://github.com/theupdateframework/tuf/tree/develop/tests)
+directory.
+
+```
+$ python aggregate_tests.py
+```
+
+Note: integration tests end in `_integration.py`.
+
+If you wish to run a particular unit test, navigate to the tests directory and
+run that specific unit test.  For example:
+
+```
+$ python test_updater.py
+```
+
+It it also possible to run the test cases of a unit test.  For instance:
+
+```
+$ python -m unittest test_updater.TestMultiRepoUpdater.test_get_one_valid_targetinfo
+```
+
+## Setup
+The unit and integration tests operate on static metadata available in the
+[repository_data
+directory](https://github.com/theupdateframework/tuf/tree/develop/tests/repository_data/).
+Before running the tests, static metadata is first copied to temporary
+directories and modified, as needed, by the tests.
+
+The test modules typically spawn HTTP(S) servers that serve metadata and target
+files for the the unit tests.  The [map
+file](https://github.com/theupdateframework/tuf/tree/develop/tests/repository_data)
+specifies the location of the test repositories and other properties.  For
+specific targets and metadata provided by the tests repositories, please
+inspect their [respective
+metadata](https://github.com/theupdateframework/tuf/tree/develop/tests/repository_data/repository).
+