Deprecate raises(..., 'code(as_a_string)') / `warns(..., 'code(as_a_string)')

doc/en/assert.rst

@@ -100,10 +100,9 @@ If you want to write test code that works on Python 2.4 as well,
 you may also use two other ways to test for an expected exception::
 
     pytest.raises(ExpectedException, func, *args, **kwargs)
-    pytest.raises(ExpectedException, "func(*args, **kwargs)")
 
-both of which execute the specified function with args and kwargs and
-asserts that the given ``ExpectedException`` is raised.  The reporter will
+which will execute the specified function with args and kwargs and
+assert 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*.
 

doc/en/deprecations.rst

@@ -14,6 +14,41 @@ Below is a complete list of all pytest features which are considered deprecated.
 :class:`_pytest.warning_types.PytestWarning` or subclasses, which can be filtered using
 :ref:`standard warning filters <warnings>`.
 
+.. _raises-warns-exec:
+
+``raises`` / ``warns`` with a string as the second argument
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. deprecated:: 4.1
+
+Use the context manager form of these instead.  When necessary, invoke ``exec``
+directly.
+
+Example:
+
+.. code-block:: python
+
+    pytest.raises(ZeroDivisionError, "1 / 0")
+    pytest.raises(SyntaxError, "a $ b")
+
+    pytest.warns(DeprecationWarning, "my_function()")
+    pytest.warns(SyntaxWarning, "assert(1, 2)")
+
+Becomes:
+
+.. code-block:: python
+
+    with pytest.raises(ZeroDivisionError):
+        1 / 0
+    with pytest.raises(SyntaxError):
+        exec("a $ b")  # exec is required for invalid syntax
+
+    with pytest.warns(DeprecationWarning):
+        my_function()
+    with pytest.warns(SyntaxWarning):
+        exec("assert(1, 2)")  # exec is used to avoid a top-level warning
+
+
 Internal classes accessed through ``Node``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

doc/en/example/assertion/failure_demo.py

@@ -165,11 +165,11 @@ def globf(x):
 
 class TestRaises(object):
     def test_raises(self):
-        s = "qwe"  # NOQA
-        raises(TypeError, "int(s)")
+        s = "qwe"
+        raises(TypeError, int, s)
 
     def test_raises_doesnt(self):
-        raises(IOError, "int('3')")
+        raises(IOError, int, "3")
 
     def test_raise(self):
         raise ValueError("demo error")

doc/en/example/parametrize.rst

@@ -388,7 +388,8 @@ parametrizer`_ but in a lot less code::
             assert a == b
 
         def test_zerodivision(self, a, b):
-            pytest.raises(ZeroDivisionError, "a/b")
+            with pytest.raises(ZeroDivisionError):
+                a / b
 
 Our test generator looks up a class-level definition which specifies which
 argument sets to use for each test function.  Let's run it: