Fix broken links

Author: pfheatwole

doc/en/fixture.rst

@@ -11,7 +11,7 @@ pytest fixtures: explicit, modular, scalable
 
 .. _`xUnit`: http://en.wikipedia.org/wiki/XUnit
 .. _`purpose of test fixtures`: http://en.wikipedia.org/wiki/Test_fixture#Software
-.. _`Dependency injection`: http://en.wikipedia.org/wiki/Dependency_injection#Definition
+.. _`Dependency injection`: http://en.wikipedia.org/wiki/Dependency_injection
 
 The `purpose of test fixtures`_ is to provide a fixed baseline
 upon which tests can reliably and repeatedly execute.   pytest fixtures

doc/en/goodpractices.rst

@@ -147,7 +147,7 @@ dependencies are isolated from the system Python installation.
 If you frequently release code and want to make sure that your actual
 package passes all tests you may want to look into `tox`_, the
 virtualenv test automation tool and its `pytest support
-<http://testrun.org/tox/latest/example/pytest.html>`_.
+<https://tox.readthedocs.io/en/latest/example/pytest.html>`_.
 Tox helps you to setup virtualenv environments with pre-defined
 dependencies and then executing a pre-configured test command with
 options.  It will run tests against the installed package and not

doc/en/writing_plugins.rst

@@ -172,7 +172,7 @@ If a package is installed this way, ``pytest`` will load
 .. note::
 
     Make sure to include ``Framework :: Pytest`` in your list of
-    `PyPI classifiers <https://python-packaging-user-guide.readthedocs.io/en/latest/distributing/#classifiers>`_
+    `PyPI classifiers <https://python-packaging-user-guide.readthedocs.io/distributing/#classifiers>`_
     to make it easy for users to find your plugin.