merge Ronny's changes, add some documentation and changelog entries

--HG--
branch : trunk

CHANGELOG

@@ -4,6 +4,14 @@ Changes between 1.3.1 and 1.3.x
 New features 
 ++++++++++++++++++
 
+- fix issue103: introduce additional "with py.test.raises(exc):" form, example::
+
+    with py.test.raises(ZeroDivisionError):
+        x = 0
+        1 / x
+
+  (thanks Ronny Pfannschmidt) 
+
 - Funcarg factories can now dynamically apply a marker to a 
   test invocation.  This is particularly useful if a factory
   provides parameters to a test which you expect-to-fail:

doc/test/features.txt

@@ -130,14 +130,20 @@ first failed and then succeeded.
 asserting expected exceptions 
 ----------------------------------------
 
-In order to write assertions about exceptions, you use
+In order to write assertions about exceptions, you can use
-one of two forms::
+``py.test.raises`` as a context manager like this:: 
 
-    py.test.raises(Exception, func, *args, **kwargs) 
+    with py.test.raises(ZeroDivisionError):
-    py.test.raises(Exception, "func(*args, **kwargs)")
+        1 / 0
+
+If you want to write test code that works on Python2.4 as well, 
+you may also use two other ways to test for an expected exception::
+
+    py.test.raises(ExpectedException, func, *args, **kwargs) 
+    py.test.raises(ExpectedException, "func(*args, **kwargs)")
 
 both of which execute the specified function with args and kwargs and
-asserts that the given ``Exception`` is raised.  The reporter will
+asserts that the given ``ExpectedException`` is raised.  The reporter will
 provide you with helpful output in case of failures such as *no
 exception* or *wrong exception*.
 

py/_path/gateway/__init__.py

@@ -1 +0,0 @@
-#

py/_path/gateway/channeltest.py

@@ -1,65 +0,0 @@
-import threading
-
-
-class PathServer:
-
-    def __init__(self, channel):
-        self.channel = channel
-        self.C2P = {}
-        self.next_id = 0
-        threading.Thread(target=self.serve).start()
-
-    def p2c(self, path):
-        id = self.next_id
-        self.next_id += 1
-        self.C2P[id] = path
-        return id
-
-    def command_LIST(self, id, *args):
-        path = self.C2P[id]
-        answer = [(self.p2c(p), p.basename) for p in path.listdir(*args)]
-        self.channel.send(answer)
-
-    def command_DEL(self, id):
-        del self.C2P[id]
-
-    def command_GET(self, id, spec):
-        path = self.C2P[id]
-        self.channel.send(path._getbyspec(spec))
-
-    def command_READ(self, id):
-        path = self.C2P[id]
-        self.channel.send(path.read())
-
-    def command_JOIN(self, id, resultid, *args):
-        path = self.C2P[id]
-        assert resultid not in self.C2P
-        self.C2P[resultid] = path.join(*args)
-
-    def command_DIRPATH(self, id, resultid):
-        path = self.C2P[id]
-        assert resultid not in self.C2P
-        self.C2P[resultid] = path.dirpath()
-
-    def serve(self):
-        try:
-            while 1:
-                msg = self.channel.receive()
-                meth = getattr(self, 'command_' + msg[0])
-                meth(*msg[1:])
-        except EOFError:
-            pass
-
-if __name__ == '__main__':
-    import py
-    gw = execnet.PopenGateway()
-    channel = gw._channelfactory.new()
-    srv = PathServer(channel)
-    c = gw.remote_exec("""
-        import remotepath
-        p = remotepath.RemotePath(channel.receive(), channel.receive())
-        channel.send(len(p.listdir()))
-    """)
-    c.send(channel)
-    c.send(srv.p2c(py.path.local('/tmp')))
-    print(c.receive())

py/_path/gateway/channeltest2.py

@@ -1,21 +0,0 @@
-import py
-from remotepath import RemotePath
-
-
-SRC = open('channeltest.py', 'r').read()
-
-SRC += '''
-import py
-srv = PathServer(channel.receive())
-channel.send(srv.p2c(py.path.local("/tmp")))
-'''
-
-
-#gw = execnet.SshGateway('codespeak.net')
-gw = execnet.PopenGateway()
-gw.remote_init_threads(5)
-c = gw.remote_exec(SRC, stdout=py.std.sys.stdout, stderr=py.std.sys.stderr)
-subchannel = gw._channelfactory.new()
-c.send(subchannel)
-
-p = RemotePath(subchannel, c.receive())

py/_path/gateway/remotepath.py

@@ -1,47 +0,0 @@
-import py, itertools
-from py._path import common
-
-COUNTER = itertools.count()
-
-class RemotePath(common.PathBase):
-    sep = '/'
-
-    def __init__(self, channel, id, basename=None):
-        self._channel = channel
-        self._id = id
-        self._basename = basename
-        self._specs = {}
-
-    def __del__(self):
-        self._channel.send(('DEL', self._id))
-
-    def __repr__(self):
-        return 'RemotePath(%s)' % self.basename
-
-    def listdir(self, *args):
-        self._channel.send(('LIST', self._id) + args)
-        return [RemotePath(self._channel, id, basename)
-                for (id, basename) in self._channel.receive()]
-
-    def dirpath(self):
-        id = ~COUNTER.next()
-        self._channel.send(('DIRPATH', self._id, id))
-        return RemotePath(self._channel, id)
-
-    def join(self, *args):
-        id = ~COUNTER.next()
-        self._channel.send(('JOIN', self._id, id) + args)
-        return RemotePath(self._channel, id)
-
-    def _getbyspec(self, spec):
-        parts = spec.split(',')
-        ask = [x for x in parts  if x not in self._specs]
-        if ask:
-            self._channel.send(('GET', self._id, ",".join(ask)))
-            for part, value in zip(ask, self._channel.receive()):
-                self._specs[part] = value
-        return [self._specs[x] for x in parts]
-
-    def read(self):
-        self._channel.send(('READ', self._id))
-        return self._channel.receive()

py/_plugin/pytest_runner.py

@@ -353,18 +353,30 @@ def xfail(reason=""):
 xfail.Exception = XFailed
 
 def raises(ExpectedException, *args, **kwargs):
-    """ if args[0] is callable: raise AssertionError if calling it with 
+    """ assert that a code block/function call raises an exception. 
+        
+        If using Python 2.5 or above, you may use this function as a 
+        context manager::
+
+        >>> with raises(ZeroDivisionError):
+        ...    1/0
+
+        Or you can one of two forms: 
+
+        if args[0] is callable: raise AssertionError if calling it with 
         the remaining arguments does not raise the expected exception.  
         if args[0] is a string: raise AssertionError if executing the
         the string in the calling scope does not raise expected exception. 
-        for examples:
+        examples:
-        x = 5
+        >>> x = 5
-        raises(TypeError, lambda x: x + 'hello', x=x)
+        >>> raises(TypeError, lambda x: x + 'hello', x=x)
-        raises(TypeError, "x + 'hello'")
+        >>> raises(TypeError, "x + 'hello'")
     """
-    __tracebackhide__ = True 
+    __tracebackhide__ = True
-    assert args
+
-    if isinstance(args[0], str):
+    if not args:
+        return RaisesContext(ExpectedException)
+    elif isinstance(args[0], str):
         code, = args
         assert isinstance(code, str)
         frame = sys._getframe(1)
@@ -391,6 +403,26 @@ def raises(ExpectedException, *args, **kwargs):
     raise ExceptionFailure(msg="DID NOT RAISE", 
                            expr=args, expected=ExpectedException) 
 
+
+class RaisesContext(object):
+
+    def __init__(self, ExpectedException):
+        self.ExpectedException = ExpectedException
+        self.excinfo = None
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *tp):
+        __tracebackhide__ = True
+        if tp[0] is None:
+            raise ExceptionFailure(msg="DID NOT RAISE",
+                                   expr=(),
+                                   expected=self.ExpectedException)
+        self.excinfo = py.code.ExceptionInfo(tp)
+        return issubclass(self.excinfo.type, self.ExpectedException)
+
+
 raises.Exception = ExceptionFailure
 
 def importorskip(modname, minversion=None):

testing/plugin/test_pytest_runner.py

@@ -340,6 +340,37 @@ class TestRaises:
         except py.test.raises.Exception:
             pass
 
+    @py.test.mark.skipif('sys.version < "2.5"')
+    def test_raises_as_contextmanager(self, testdir):
+        testdir.makepyfile("""
+            from __future__ import with_statement
+            import py
+
+            def test_simple():
+                with py.test.raises(ZeroDivisionError) as ctx:
+                    1/0
+
+                print ctx.excinfo
+                assert ctx.excinfo.type is ZeroDivisionError
+
+
+            def test_noraise():
+                with py.test.raises(py.test.raises.Exception):
+                    with py.test.raises(ValueError):
+                           int()
+
+            def test_raise_wrong_exception_passes_by():
+                with py.test.raises(ZeroDivisionError):
+                    with py.test.raises(ValueError):
+                           1/0
+        """)
+        result = testdir.runpytest()
+        result.stdout.fnmatch_lines([
+            '*3 passed*',
+        ])
+
+
+
 def test_pytest_exit():
     try:
         py.test.exit("hello")