Fix a bug in the way `default_renderer` is applied.

When an explicit `content_type` is specified to `pecan.expose()`, it should
always take precendece over the `default_renderer` specified at the application
level.

Fixes-bug: #1465688

Change-Id: I633777a3d682f17b7f61cbe691c6e93f2ce2a310

3 files changed, 22 insertions, 5 deletions

diff --git a/pecan/core.py b/pecan/core.py
index 14b9ad3..050687c 100644
--- a/pecan/core.py
+++ b/pecan/core.py
@@ -585,9 +585,11 @@ class PecanBase(object):
         template = content_types.get(pecan_state['content_type'])
 
         # check if for controller override of template
-        template = pecan_state.get('override_template', template) or (
-            'json' if self.default_renderer == 'json' else None
-        )
+        template = pecan_state.get('override_template', template)
+        if template is None and cfg['explicit_content_type'] is False:
+            if self.default_renderer == 'json':
+                template = 'json'
+
         pecan_state['content_type'] = pecan_state.get(
             'override_content_type',
             pecan_state['content_type']
diff --git a/pecan/decorators.py b/pecan/decorators.py
index 68195a9..15808d4 100644
--- a/pecan/decorators.py
+++ b/pecan/decorators.py
@@ -23,9 +23,9 @@ def when_for(controller):
 
 
 def expose(template=None,
-           content_type='text/html',
            generic=False,
-           route=None):
+           route=None,
+           **kw):
 
     '''
     Decorator used to flag controller methods as being "exposed" for
@@ -46,6 +46,8 @@ def expose(template=None,
                   wanted to route a function to `some-special-path'.
     '''
 
+    content_type = kw.get('content_type', 'text/html')
+
     if template == 'json':
         content_type = 'application/json'
 
@@ -54,6 +56,7 @@ def expose(template=None,
         f.exposed = True
 
         cfg = _cfg(f)
+        cfg['explicit_content_type'] = 'content_type' in kw
 
         if route:
             # This import is here to avoid a circular import issue
diff --git a/pecan/tests/test_base.py b/pecan/tests/test_base.py
index 785b522..44f87db 100644
--- a/pecan/tests/test_base.py
+++ b/pecan/tests/test_base.py
@@ -1957,6 +1957,18 @@ class TestEngines(PecanTestCase):
         result = dict(json.loads(r.body.decode()))
         assert result == {'name': 'Bill'}
 
+    def test_default_json_renderer_with_explicit_content_type(self):
+
+        class RootController(object):
+            @expose(content_type='text/plain')
+            def index(self, name='Bill'):
+                return name
+
+        app = TestApp(Pecan(RootController(), default_renderer='json'))
+        r = app.get('/')
+        assert r.status_int == 200
+        assert r.body == b_("Bill")
+
 
 class TestDeprecatedRouteMethod(PecanTestCase):