Issue #18566: Clarify unittest setUp, tearDown doc. Patch by Nitika Agarwal.

Doc/library/unittest.rst

@@ -719,9 +719,9 @@ Test cases
    .. method:: setUp()
 
       Method called to prepare the test fixture.  This is called immediately
-      before calling the test method; any exception raised by this method will
+      before calling the test method; other than :exc:`AssertionError` or :exc:`SkipTest`, 
-      be considered an error rather than a test failure. The default
+      any exception raised by this method will be considered an error rather than 
-      implementation does nothing.
+      a test failure. The default implementation does nothing.
 
 
    .. method:: tearDown()
@@ -729,10 +729,10 @@ Test cases
       Method called immediately after the test method has been called and the
       result recorded.  This is called even if the test method raised an
       exception, so the implementation in subclasses may need to be particularly
-      careful about checking internal state.  Any exception raised by this
+      careful about checking internal state.  Any exception, other than :exc:`AssertionError` 
-      method will be considered an error rather than a test failure.  This
+      or :exc:`SkipTest`, raised by this method will be considered an error rather than a 
-      method will only be called if the :meth:`setUp` succeeds, regardless of
+      test failure.  This method will only be called if the :meth:`setUp` succeeds, 
-      the outcome of the test method. The default implementation does nothing.
+      regardless of the outcome of the test method. The default implementation does nothing.
 
 
    .. method:: setUpClass()

Misc/ACKS

@@ -18,6 +18,7 @@ David Abrahams
 Marc Abramowitz
 Ron Adam
 Ali Afshar
+Nitika Agarwal
 Jim Ahlstrom
 Farhan Ahmad
 Matthew Ahrens