Switched on deprecation warning for old API by default

CHANGES.md

@@ -3,8 +3,15 @@ The release versions are PyPi releases.
 
 ## Version 3.5 (as yet unreleased)
 
-This version of pyfakefs does not support Python 3.3. Python 3.3 users shall 
-keep using pyfakefs 3.4.3, or upgrade to a newer Python version.
+#### Changes
+  * This version of pyfakefs does not support Python 3.3. Python 3.3 users 
+    must keep using pyfakefs 3.4.3, or upgrade to a newer Python version.
+  * The deprecation warnings for the old API are now switched on by default.
+    To switch them off for legacy code, use:
+    ```python
+    from pyfakefs.deprecator import Deprecator
+    Deprecator.show_warnings = False
+    ```
 
 #### New Features
   * a module imported as another name (`import os as _os`) is now correctly 
@@ -21,8 +28,6 @@ keep using pyfakefs 3.4.3, or upgrade to a newer Python version.
   ([#423](../../issues/423)) 
   * added support for null device ([#418](../../issues/418))
 
-#### Infrastructure
-
 #### Fixes
   * file timestamps are now updated more according to the real behavior
     ([#435](../../issues/435))

README.md

@@ -64,7 +64,6 @@ pyfakefs is currently automatically tested:
   on Linux, with Python 2.7, and 3.4 to 3.7, using [Travis](https://travis-ci.org/jmcgeheeiv/pyfakefs)
 * [![Build Status](https://travis-ci.org/jmcgeheeiv/pyfakefs.svg)](https://travis-ci.org/jmcgeheeiv/pyfakefs)
   on MacOS, with Python 2.7, 3.6 and 3.7, using [Travis](https://travis-ci.org/jmcgeheeiv/pyfakefs)
-  [![Build Status](https://travis-ci.org/jmcgeheeiv/pyfakefs.svg)](https://travis-ci.org/jmcgeheeiv/pyfakefs)
 * [![Build status](https://ci.appveyor.com/api/projects/status/4o8j21ufuo056873/branch/master?svg=true)](https://ci.appveyor.com/project/jmcgeheeiv/pyfakefs/branch/master)
   on Windows, with Python 2.7, and 3.4 to 3.7 using [Appveyor](https://ci.appveyor.com/project/jmcgeheeiv/pyfakefs)
 

pyfakefs/deprecator.py

@@ -18,15 +18,15 @@
 class Deprecator(object):
     """Decorator class for adding deprecated functions.
 
-    Warnings are switched off by default.
-    To enable deprecation warnings, use:
+    Warnings are switched on by default.
+    To disable deprecation warnings, use:
 
     >>>  from pyfakefs.deprecator import Deprecator
     >>>
-    >>>  Deprecator.show_warnings = True
+    >>>  Deprecator.show_warnings = False
     """
 
-    show_warnings = False
+    show_warnings = True
 
     def __init__(self, use_instead=None, func_name=None):
         self.use_instead = use_instead