Made it possible to create the session after start_response is called but before the first content is sent to the server

2 files changed, 67 insertions, 4 deletions

diff --git a/paste/session.py b/paste/session.py
index b10601f..c2feac6 100644
--- a/paste/session.py
+++ b/paste/session.py
@@ -42,18 +42,29 @@ class SessionMiddleware(object):
     def __call__(self, environ, start_response):
         session_factory = SessionFactory(environ, **self.factory_kw)
         environ['paste.session.factory'] = session_factory
+        remember_headers = []
 
         def session_start_response(status, headers, exc_info=None):
             if not session_factory.created:
+                remember_headers[:] = [status, headers]
                 return start_response(status, headers)
             headers.append(session_factory.set_cookie_header())
             return start_response(status, headers, exc_info)
 
         app_iter = self.application(environ, session_start_response)
-        if session_factory.used:
-            return wsgilib.add_close(app_iter, session_factory.close)
-        else:
-            return app_iter
+        def start():
+            if session_factory.created and remember_headers:
+                # Tricky bastard used the session after start_response
+                status, headers = remember_headers
+                headers.append(session_factory.set_cookie_header())
+                exc = ValueError(
+                    "You cannot get the session after content from the "
+                    "app_iter has been returned")
+                start_response(status, headers, (exc.__class__, exc, None))
+        def close():
+            if session_factory.used:
+                session_factory.close()
+        return wsgilib.add_start_close(app_iter, start, close)
 
 class SessionFactory(object):
 
diff --git a/tests/test_session.py b/tests/test_session.py
new file mode 100644
index 0000000..621d284
--- /dev/null
+++ b/tests/test_session.py
@@ -0,0 +1,52 @@
+from paste.session import SessionMiddleware
+from paste.fixture import TestApp
+
+info = []
+
+def wsgi_app(environ, start_response):
+    pi = environ.get('PATH_INFO', '')
+    if pi in ('/get1', '/get2'):
+        if pi == '/get1':
+            sess = environ['paste.session.factory']()
+        start_response('200 OK', [('content-type', 'text/plain')])
+        if pi == '/get2':
+            sess = environ['paste.session.factory']()
+        if 'info' in sess:
+            return [str(sess['info'])]
+        else:
+            return ['no-info']
+    if pi in ('/put1', '/put2'):
+        if pi == '/put1':
+            sess = environ['paste.session.factory']()
+            sess['info']  = info[0]
+        start_response('200 OK', [('content-type', 'text/plain')])
+        if pi == '/put2':
+            sess = environ['paste.session.factory']()
+            sess['info']  = info[0]
+        return ['foo']
+
+wsgi_app = SessionMiddleware(wsgi_app)
+    
+def test_app1():
+    app = TestApp(wsgi_app)
+    res = app.get('/get1')
+    assert res.body == 'no-info'
+    res = app.get('/get2')
+    assert res.body == 'no-info'
+    info[:] = ['test']
+    res = app.get('/put1')
+    res = app.get('/get1')
+    assert res.body == 'test'
+    res = app.get('/get2')
+    assert res.body == 'test'
+
+def test_app2():
+    app = TestApp(wsgi_app)
+    info[:] = ['fluff']
+    res = app.get('/put2')
+    res = app.get('/get1')
+    assert res.body == 'fluff'
+    res = app.get('/get2')
+    assert res.body == 'fluff'
+    
+