Use default redirect when nothing matches.

Issue #86

tests/test_handler.py

@@ -40,8 +40,8 @@ def test_redirect_with_mime_match(self, urihandler):
     def test_redirect_with_mime_no_match(self, urihandler):
         req = testing.DummyRequest(accept="application/pdf")
         req.host_url = "http://test.urihandler.org"
-        with pytest.raises(HTTPNotAcceptable):
-            urihandler.handle("http://test.urihandler.org/foobar/18", req)
+        res = urihandler.handle("http://test.urihandler.org/foobar/18", req)
+        assert res == "http://localhost:5555/foobar/18"
 
     def test_redirect_default_mime(self, urihandler):
         req = testing.DummyRequest()

urihandler/handler.py

@@ -34,23 +34,39 @@ def handle(self, uri, request):
             if m:
                 redirect = u["redirect"]
                 if isinstance(redirect, dict):
-                    if isinstance(request.accept, AcceptNoHeader):
-                        redirect = redirect.get("default")
-                        if not redirect:
-                            raise HTTPNotAcceptable()
-                    else:
-                        for mime, redirect in redirect.items():
-                            if mime in request.accept:
-                                break
-                        else:
-                            # No matching mime was found.
-                            raise HTTPNotAcceptable()
+                    redirect = _get_redirect_based_on_accept_header(request.accept, redirect)
                 redirect = redirect.format(**m.groupdict())
                 log.debug(f"Match found. Redirecting to {redirect}.")
                 return redirect
         return None
 
 
+def _get_redirect_based_on_accept_header(accept_header, redirect_rule):
+    """
+    Return the redirect rule based on accept header.
+
+    At its core it simply looks for a matching mime between accept header
+    and the configured mime type redirects. But exceptions apply.
+
+    If there is no accept header specified or if no matching mime is found,
+    the default will be returned. If default is not set, HTTP 406 gets raised.
+    """
+    default = redirect_rule.get("default")
+    if isinstance(accept_header, AcceptNoHeader):
+        if not default:
+            raise HTTPNotAcceptable()
+        return default
+
+    for mime, redirect in redirect_rule.items():
+        if mime in accept_header:
+            return redirect
+
+    if not default:
+        raise HTTPNotAcceptable()
+
+    return default
+
+
 def _build_uri_handler(registry, handlerconfig):
     """
     :param pyramid.registry.Registry registry: Pyramid registry