DEV: improve usability of subfolder specs

Previously people were not consistent about mocking which left internals in
a fragile state when running subfolder specs.

This introduces a simple helper `set_subfolder` which you can use to set
the subfolder for the spec. It takes care of proper configuration of subfolder
and teardown.

```
# usage
set_subfolder "/my_amazing_subfolder"
```

You should no longer stub base_uri or global_settings

spec/components/cooked_post_processor_spec.rb

@@ -558,14 +558,12 @@ describe CookedPostProcessor do
         end
 
         let(:cpp) { CookedPostProcessor.new(post, disable_loading_image: true) }
-        let(:base_url) { "http://test.localhost/subfolder" }
-        let(:base_uri) { "/subfolder" }
 
         before do
+          set_subfolder "/subfolder"
+
           SiteSetting.max_image_height = 2000
           SiteSetting.create_thumbnails = true
-          Discourse.stubs(:base_url).returns(base_url)
-          Discourse.stubs(:base_uri).returns(base_uri)
           FastImage.expects(:size).returns([1750, 2000])
           OptimizedImage.expects(:resize).returns(true)
 

spec/components/file_store/local_store_spec.rb

@@ -114,11 +114,6 @@ describe FileStore::LocalStore do
 
   end
 
-  def stub_for_subfolder
-    GlobalSetting.stubs(:relative_url_root).returns('/forum')
-    Discourse.stubs(:base_uri).returns("/forum")
-  end
-
   describe "#absolute_base_url" do
 
     it "is present" do
@@ -126,7 +121,7 @@ describe FileStore::LocalStore do
     end
 
     it "supports subfolder" do
-      stub_for_subfolder
+      set_subfolder "/forum"
       expect(store.absolute_base_url).to eq("http://test.localhost/forum/uploads/default")
     end
 
@@ -139,7 +134,7 @@ describe FileStore::LocalStore do
     end
 
     it "supports subfolder" do
-      stub_for_subfolder
+      set_subfolder "/forum"
       expect(store.relative_base_url).to eq("/forum/uploads/default")
     end
 

spec/components/file_store/s3_store_spec.rb

@@ -386,8 +386,7 @@ describe FileStore::S3Store do
 
       # none of this should matter at all
       # subfolder should not leak into uploads
-      global_setting :relative_url_root, '/community'
-      Discourse.stubs(:base_uri).returns("/community")
+      set_subfolder "/community"
 
       url = "//s3-upload-bucket.s3.dualstack.us-east-1.amazonaws.com/livechat/original/gif.png"
 

spec/components/pretty_text_spec.rb

@@ -269,12 +269,8 @@ describe PrettyText do
       fab!(:user) { Fabricate(:user) }
 
       context "subfolder" do
-        before do
-          GlobalSetting.stubs(:relative_url_root).returns("/forum")
-          Discourse.stubs(:base_uri).returns("/forum")
-        end
-
         it "should have correct avatar url" do
+          set_subfolder "/forum"
           md = <<~MD
             [quote="#{user.username}, post:123, topic:456, full:true"]
             ddd
@@ -331,12 +327,9 @@ describe PrettyText do
     end
 
     context 'subfolder' do
-      before do
-        GlobalSetting.stubs(:relative_url_root).returns('/forum')
-        Discourse.stubs(:base_uri).returns("/forum")
-      end
-
       it "handles user and group mentions correctly" do
+        set_subfolder "/forum"
+
         Fabricate(:user, username: 'user1')
         Fabricate(:group, name: 'groupA', mentionable_level: Group::ALIAS_LEVELS[:everyone])
 

spec/components/topic_view_spec.rb

@@ -214,12 +214,8 @@ describe TopicView do
     end
 
     context 'subfolder' do
-      before do
-        GlobalSetting.stubs(:relative_url_root).returns('/forum')
-        Discourse.stubs(:base_uri).returns("/forum")
-      end
-
       it "provides the correct absolute url" do
+        set_subfolder "/forum"
         expect(topic_view.absolute_url).to eq("http://test.localhost/forum/t/#{topic.slug}/#{topic.id}")
       end
     end

spec/components/url_helper_spec.rb

@@ -33,7 +33,8 @@ describe UrlHelper do
       store = stub
       store.expects(:has_been_uploaded?).returns(false)
       Discourse.stubs(:store).returns(store)
-      Discourse.stubs(:base_uri).returns("/subpath")
+
+      set_subfolder "/subpath"
       expect(UrlHelper.is_local("/subpath/assets/javascripts/all.js")).to eq(true)
     end