From 387878f39c403c4b2fced56704ca9832ba5395f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bartek=20Bu=C5=82at?= <barthez@users.noreply.github.com>
Date: Mon, 8 May 2017 16:23:13 +0200
Subject: [PATCH] Clean view context when controller changes (#799)

When we reassign controller it is the right thing to do to clear current
view context stored in request store. Consider a case when view context
was built before the request was made (usage of `h` helper in class level
context). View context is built from default controller and has no
information about the request. During first request
`Draper::ViewContext.current.controller` will be different than
`Draper::ViewContext.controller`.
---
 lib/draper/view_context.rb       |  4 +++-
 spec/draper/view_context_spec.rb | 28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/draper/view_context.rb b/lib/draper/view_context.rb
index 9634d25..d0d05bb 100644
--- a/lib/draper/view_context.rb
+++ b/lib/draper/view_context.rb
@@ -20,8 +20,10 @@ module Draper
       RequestStore.store[:current_controller]
     end
 
-    # Sets the current controller.
+    # Sets the current controller. Clears view context when we are setting
+    # different controller.
     def self.controller=(controller)
+      clear! if RequestStore.store[:current_controller] != controller
       RequestStore.store[:current_controller] = controller
     end
 
diff --git a/spec/draper/view_context_spec.rb b/spec/draper/view_context_spec.rb
index 1816cd1..e62008c 100644
--- a/spec/draper/view_context_spec.rb
+++ b/spec/draper/view_context_spec.rb
@@ -32,6 +32,34 @@ module Draper
         ViewContext.controller = :stored_controller
         expect(store[:current_controller]).to be :stored_controller
       end
+
+      it "cleans context when controller changes" do
+        store = {
+          current_controller: :stored_controller,
+          current_view_context: :stored_view_context
+        }
+
+        allow(RequestStore).to receive_messages store: store
+
+        ViewContext.controller = :other_stored_controller
+
+        expect(store).to include(current_controller: :other_stored_controller)
+        expect(store).not_to include(:current_view_context)
+      end
+
+      it "doesn't clean context when controller is the same" do
+        store = {
+          current_controller: :stored_controller,
+          current_view_context: :stored_view_context
+        }
+
+        allow(RequestStore).to receive_messages store: store
+
+        ViewContext.controller = :stored_controller
+
+        expect(store).to include(current_controller: :stored_controller)
+        expect(store).to include(current_view_context: :stored_view_context)
+      end
     end
 
     describe ".current" do