get rid of reference to old test runner + update test instructions

psutil/tests/README.rst

@@ -1,14 +1,40 @@
 Instructions for running tests
 ==============================
 
-* There are two ways of running tests. As a "user", if psutil is already
-  installed and you just want to test it works::
+Setup:
+
+.. code-block:: bash
+
+    make install-pydeps-test  # install pytest
+
+There are two ways of running tests. As a "user", if psutil is already
+installed and you just want to test it works on your system:
+
+.. code-block:: bash
 
     python -m psutil.tests
 
-  As a "developer", if you have a copy of the source code and you wish to hack
-  on psutil::
+As a "developer", if you have a copy of the source code and you're working on
+it:
+
+.. code-block:: bash
+
+    make test
+
+You can run tests in parallel with:
+
+.. code-block:: bash
+
+    make test-parallel
+
+You can run a specific test with:
+
+.. code-block:: bash
+
+    make test ARGS=psutil.tests.test_system.TestDiskAPIs
+
+You can run memory leak tests with:
+
+.. code-block:: bash
 
-    make install-pydeps  # install missing third-party deps
-    make test           # serial run
-    make test-parallel  # parallel run
+    make test-parallel

psutil/tests/__main__.py

@@ -6,7 +6,7 @@
 $ python -m psutil.tests.
 """
 
-from .runner import main
+import pytest
 
 
-main()
+pytest.main(["-v", "-s", "--tb=short"])