Upgrade to coverage 3.7.1 and have it auto-build itself on first use.

third_party/coverage-3.6/doc/excluding.rst

-.. _excluding:
-
-============================
-Excluding code from coverage
-============================
-
-:history: 20090613T090500, brand new docs.
-:history: 20100224T200900, updated for 3.3.
-:history: 20100725T211700, updated for 3.4.
-:history: 20110604T184400, updated for 3.5.
-
-
-You may have code in your project that you know won't be executed, and you want
-to tell coverage to ignore it.  For example, you may have debugging-only code
-that won't be executed during your unit tests. You can tell coverage to exclude
-this code during reporting so that it doesn't clutter your reports with noise
-about code that you don't need to hear about.
-
-Coverage will look for comments marking clauses for exclusion.  In this code,
-the "if debug" clause is excluded from reporting::
-
-    a = my_function1()
-    if debug:   # pragma: no cover
-        msg = "blah blah"
-        log_message(msg, a)
-    b = my_function2()
-
-Any line with a comment of "pragma: no cover" is excluded.  If that line
-introduces a clause, for example, an if clause, or a function or class
-definition, then the entire clause is also excluded.  Here the __repr__
-function is not reported as missing::
-
-    class MyObject(object):
-        def __init__(self):
-            blah1()
-            blah2()
-
-        def __repr__(self): # pragma: no cover
-            return "<MyObject>"
-
-Excluded code is executed as usual, and its execution is recorded in the
-coverage data as usual. When producing reports though, coverage excludes it from
-the list of missing code.
-
-
-Branch coverage
----------------
-
-When measuring :ref:`branch coverage <branch>`, a condtional will not be
-counted as a branch if one of its choices is excluded::
-
-    def only_one_choice(x):
-        if x:
-            blah1()
-            blah2()
-        else:       # pragma: no cover
-            # x is always true.
-            blah3()
-
-Because the ``else`` clause is excluded, the ``if`` only has one possible
-next line, so it isn't considered a branch at all.
-
-
-Advanced exclusion
-------------------
-
-Coverage identifies exclusions by matching lines against a list of regular
-expressions. Using :ref:`configuration files <config>` or the coverage
-:ref:`API <api>`, you can add to that list. This is useful if you have
-often-used constructs to exclude that can be matched with a regex. You can
-exclude them all at once without littering your code with exclusion pragmas.
-
-For example, you might decide that __repr__ functions are usually only used
-in debugging code, and are uninteresting to test themselves.  You could exclude
-all of them by adding a regex to the exclusion list::
-
-    [report]
-    exclude_lines = def __repr__
-
-For example, here's a list of exclusions I've used::
-
-    [report]
-    exclude_lines =
-        pragma: no cover
-        def __repr__
-        if self.debug:
-        if settings.DEBUG
-        raise AssertionError
-        raise NotImplementedError
-        if 0:
-        if __name__ == .__main__.:
-
-Note that when using the ``exclude_lines`` option in a configuration file, you
-are taking control of the entire list of regexes, so you need to re-specify the
-default "pragma: no cover" match if you still want it to apply.
-
-A similar pragma, "no branch", can be used to tailor branch coverage
-measurement.  See :ref:`branch` for details.
-
-
-Excluding source files
-----------------------
-
-See :ref:`source` for ways to limit what files coverage.py measures or reports
-on.