From 4a17553c25da15a94e178e9b3a27f684d2c4e07f Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Wed, 5 Nov 2025 20:08:15 -0500
Subject: [PATCH 1/8] Support view on environment for commits and compare pages
 in rapid diffs

---
 .../rapid_diffs/app_component.html.haml       |   2 +-
 app/components/rapid_diffs/app_component.rb   |   2 +-
 .../rapid_diffs/diff_file_component.rb        |   8 +-
 .../rapid_diffs/diff_file_header_component.rb |  30 +++-
 .../concerns/rapid_diffs/resource.rb          |   6 +-
 .../rapid_diffs/streaming_resource.rb         |  14 +-
 app/controllers/projects/commit_controller.rb |   7 +-
 .../projects/compare_controller.rb            |   3 +-
 app/helpers/commits_helper.rb                 |   2 +-
 app/presenters/rapid_diffs/base_presenter.rb  |   5 +-
 .../rapid_diffs/commit_presenter.rb           |   4 +-
 locale/gitlab.pot                             |   3 +
 .../rapid_diffs/diff_file_component_spec.rb   |  22 ++-
 .../diff_file_header_component_spec.rb        |  91 +++++++++++
 .../concerns/rapid_diffs/resource_spec.rb     |  37 +++++
 .../rapid_diffs/streaming_resource_spec.rb    | 144 ++++++++++++++++++
 spec/features/projects/view_on_env_spec.rb    |  69 +++++++--
 .../rapid_diffs/base_presenter_spec.rb        |  42 +++++
 18 files changed, 459 insertions(+), 32 deletions(-)

diff --git a/app/components/rapid_diffs/app_component.html.haml b/app/components/rapid_diffs/app_component.html.haml
index 622ceb854db4d8..ff5f84fa98a96b 100644
--- a/app/components/rapid_diffs/app_component.html.haml
+++ b/app/components/rapid_diffs/app_component.html.haml
@@ -40,7 +40,7 @@
               - if diffs_list?
                 = diffs_list
               - else
-                = render RapidDiffs::DiffFileComponent.with_collection(diffs_slice, parallel_view: parallel_view?)
+                = render RapidDiffs::DiffFileComponent.with_collection(diffs_slice, parallel_view: parallel_view?, environment: environment)
             - if diffs_stream_url
               %div{ data: { stream_remaining_diffs: true } }
             - else
diff --git a/app/components/rapid_diffs/app_component.rb b/app/components/rapid_diffs/app_component.rb
index 9bf74b59e2132a..3c745bd9af176d 100644
--- a/app/components/rapid_diffs/app_component.rb
+++ b/app/components/rapid_diffs/app_component.rb
@@ -8,7 +8,7 @@ class AppComponent < ViewComponent::Base
     attr_reader :presenter
 
     delegate :diffs_stream_url, :reload_stream_url, :diffs_stats_endpoint, :diff_files_endpoint, :diff_file_endpoint,
-      :should_sort_metadata_files?, :diffs_slice, :lazy?, to: :presenter
+      :should_sort_metadata_files?, :diffs_slice, :lazy?, :environment, to: :presenter
 
     delegate :diff_view, :current_user, to: :helpers
 
diff --git a/app/components/rapid_diffs/diff_file_component.rb b/app/components/rapid_diffs/diff_file_component.rb
index 6735be9229a6d9..00b7420524f7e3 100644
--- a/app/components/rapid_diffs/diff_file_component.rb
+++ b/app/components/rapid_diffs/diff_file_component.rb
@@ -7,9 +7,10 @@ class DiffFileComponent < ViewComponent::Base
 
     renders_one :header
 
-    def initialize(diff_file:, parallel_view: false)
+    def initialize(diff_file:, parallel_view: false, environment: nil)
       @diff_file = diff_file
       @parallel_view = parallel_view
+      @environment = environment
     end
 
     def id
@@ -46,7 +47,10 @@ def viewer_component_instance
     end
 
     def default_header
-      render RapidDiffs::DiffFileHeaderComponent.new(diff_file: @diff_file)
+      render RapidDiffs::DiffFileHeaderComponent.new(
+        diff_file: @diff_file,
+        environment: @environment
+      )
     end
 
     # enables virtual rendering through content-visibility: auto, significantly boosts client performance
diff --git a/app/components/rapid_diffs/diff_file_header_component.rb b/app/components/rapid_diffs/diff_file_header_component.rb
index 97092301a70bc4..ed95f050b23688 100644
--- a/app/components/rapid_diffs/diff_file_header_component.rb
+++ b/app/components/rapid_diffs/diff_file_header_component.rb
@@ -5,9 +5,10 @@ class DiffFileHeaderComponent < ViewComponent::Base
     include ButtonHelper
     include DiffHelper
 
-    def initialize(diff_file:, additional_menu_items: [])
+    def initialize(diff_file:, additional_menu_items: [], environment: nil)
       @diff_file = diff_file
       @additional_menu_items = additional_menu_items
+      @environment = environment
     end
 
     def file_title_chunks
@@ -36,12 +37,13 @@ def copy_path_button
     end
 
     def menu_items
-      [
+      @menu_items ||= [
         view_file_menu_item,
+        view_on_environment_menu_item,
         *@additional_menu_items
       ]
-      .filter_map { |item| item unless item.nil? }
-      .sort_by { |item| item[:position] || Float::INFINITY }
+                        .compact
+                        .sort_by { |item| item[:position] || Float::INFINITY }
     end
 
     def heading_id
@@ -92,5 +94,25 @@ def view_file_menu_item
         position: 1
       }
     end
+
+    def view_on_environment_menu_item
+      return unless @environment
+
+      file_path = @diff_file.new_path || @diff_file.old_path
+      commit_sha = @diff_file.content_sha
+
+      environment_path = @environment.external_url_for(file_path, commit_sha)
+      return unless environment_path
+
+      {
+        text: helpers.safe_format(
+          s_('RapidDiffs|View on %{environment}'),
+          environment: @environment.formatted_external_url
+        ),
+        href: environment_path,
+        extraAttrs: { target: '_blank', rel: 'noopener noreferrer' },
+        position: 2
+      }
+    end
   end
 end
diff --git a/app/controllers/concerns/rapid_diffs/resource.rb b/app/controllers/concerns/rapid_diffs/resource.rb
index afa0accfa219d1..4430146c46092e 100644
--- a/app/controllers/concerns/rapid_diffs/resource.rb
+++ b/app/controllers/concerns/rapid_diffs/resource.rb
@@ -53,8 +53,12 @@ def diffs_resource(options = {})
       raise NotImplementedError
     end
 
+    def environment
+      @environment
+    end
+
     def diff_file_component(base_args)
-      ::RapidDiffs::DiffFileComponent.new(**base_args)
+      ::RapidDiffs::DiffFileComponent.new(**base_args, environment: environment)
     end
 
     def find_diff_file(extra_options, old_path, new_path)
diff --git a/app/controllers/concerns/rapid_diffs/streaming_resource.rb b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
index cfc4f0545124aa..8abd471a3f237f 100644
--- a/app/controllers/concerns/rapid_diffs/streaming_resource.rb
+++ b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
@@ -85,12 +85,22 @@ def stream_diff_collection(options, view_context)
       response.stream.write(diff_files_collection(skipped).render_in(view_context)) unless skipped.empty?
     end
 
+    def environment
+      @environment
+    end
+
     def diff_file_component(diff_file)
-      ::RapidDiffs::DiffFileComponent.new(diff_file: diff_file, parallel_view: view == :parallel)
+      ::RapidDiffs::DiffFileComponent.new(
+        diff_file: diff_file,
+        parallel_view: view == :parallel,
+        environment: environment)
     end
 
     def diff_files_collection(diff_files)
-      ::RapidDiffs::DiffFileComponent.with_collection(diff_files, parallel_view: view == :parallel)
+      ::RapidDiffs::DiffFileComponent.with_collection(
+        diff_files,
+        parallel_view: view == :parallel,
+        environment: environment)
     end
 
     def stream_diff_blobs(options, view_context)
diff --git a/app/controllers/projects/commit_controller.rb b/app/controllers/projects/commit_controller.rb
index 84d52244b2ff63..9cfa9dafe86cc1 100644
--- a/app/controllers/projects/commit_controller.rb
+++ b/app/controllers/projects/commit_controller.rb
@@ -16,7 +16,9 @@ class Projects::CommitController < Projects::ApplicationController
   before_action :authorize_read_code!
   before_action :authorize_read_pipeline!, only: [:pipelines]
   before_action :commit
-  before_action :define_commit_vars, only: [:show, :diff_for_path, :diff_files, :pipelines, :merge_requests]
+  before_action :define_commit_vars, only: [
+    :show, :diff_for_path, :diff_files, :pipelines, :merge_requests, :rapid_diffs
+  ]
   before_action :define_commit_box_vars, only: [:show, :pipelines, :rapid_diffs]
   before_action :define_note_vars, only: [:show, :diff_for_path, :diff_files, :discussions]
   before_action :authorize_edit_tree!, only: [:revert, :cherry_pick]
@@ -172,7 +174,8 @@ def rapid_diffs
       diff_view,
       commit_diff_options,
       nil,
-      current_user
+      current_user,
+      @environment
     )
 
     show
diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 289844bbb5147e..4f601cd466d210 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -42,7 +42,8 @@ def show
         compare,
         diff_view,
         diff_options,
-        compare_params
+        compare_params,
+        @environment
       )
       return render action: :rapid_diffs
     end
diff --git a/app/helpers/commits_helper.rb b/app/helpers/commits_helper.rb
index 43695d948ff26b..692df57cb20138 100644
--- a/app/helpers/commits_helper.rb
+++ b/app/helpers/commits_helper.rb
@@ -279,7 +279,7 @@ def view_on_environment_button(commit_sha, diff_new_path, environment)
       button_options: {
         rel: 'noopener noreferrer',
         title: "View on #{environment.formatted_external_url}",
-        class: 'has-tooltip',
+        class: 'has-tooltip gl-ml-3',
         data: { container: 'body' }
       }
     )
diff --git a/app/presenters/rapid_diffs/base_presenter.rb b/app/presenters/rapid_diffs/base_presenter.rb
index e41a63fb02bf31..7dc6fc6a82ecc6 100644
--- a/app/presenters/rapid_diffs/base_presenter.rb
+++ b/app/presenters/rapid_diffs/base_presenter.rb
@@ -2,13 +2,16 @@
 
 module RapidDiffs
   class BasePresenter < Gitlab::View::Presenter::Delegated
-    def initialize(subject, diff_view, diff_options, request_params = nil)
+    def initialize(subject, diff_view, diff_options, request_params = nil, environment = nil)
       super(subject)
       @diff_view = diff_view
       @diff_options = diff_options
       @request_params = request_params
+      @environment = environment
     end
 
+    attr_reader :environment
+
     def diffs_stream_url
       return reload_stream_url(diff_view: @diff_view) if offset == 0
       return if offset.nil? || offset >= diffs_count
diff --git a/app/presenters/rapid_diffs/commit_presenter.rb b/app/presenters/rapid_diffs/commit_presenter.rb
index 24fef6988dd945..ec9be55bd768e2 100644
--- a/app/presenters/rapid_diffs/commit_presenter.rb
+++ b/app/presenters/rapid_diffs/commit_presenter.rb
@@ -6,8 +6,8 @@ class CommitPresenter < BasePresenter
 
     presents ::Commit, as: :resource
 
-    def initialize(subject, diff_view, diff_options, request_params = nil, current_user = nil)
-      super(subject, diff_view, diff_options, request_params)
+    def initialize(subject, diff_view, diff_options, request_params = nil, current_user = nil, environment = nil)
+      super(subject, diff_view, diff_options, request_params, environment)
       @current_user = current_user
     end
 
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index 9053489adbb0e4..e19356f41f80fb 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -54707,6 +54707,9 @@ msgstr ""
 msgid "RapidDiffs|View file at %{codeStart}%{commit}%{codeEnd}"
 msgstr ""
 
+msgid "RapidDiffs|View on %{environment}"
+msgstr ""
+
 msgid "Rate Limits"
 msgstr ""
 
diff --git a/spec/components/rapid_diffs/diff_file_component_spec.rb b/spec/components/rapid_diffs/diff_file_component_spec.rb
index e693c821bfe346..655383e49276de 100644
--- a/spec/components/rapid_diffs/diff_file_component_spec.rb
+++ b/spec/components/rapid_diffs/diff_file_component_spec.rb
@@ -13,7 +13,8 @@
     it 'renders the default header when no custom header is provided' do
       allow_next_instance_of(
         RapidDiffs::DiffFileHeaderComponent,
-        diff_file: diff_file
+        diff_file: diff_file,
+        environment: nil
       ) do |instance|
         allow(instance).to receive(:render_in).and_return('diff-file-header')
       end
@@ -32,6 +33,25 @@
 
       expect(result.css('.custom-header').text).to eq('Custom Header')
     end
+
+    context 'with environment' do
+      let_it_be(:project) { build_stubbed(:project, :repository) }
+      let_it_be(:environment) { build_stubbed(:environment, project: project) }
+
+      it 'renders the default header with environment when no custom header is provided' do
+        allow_next_instance_of(
+          RapidDiffs::DiffFileHeaderComponent,
+          diff_file: diff_file,
+          environment: environment
+        ) do |instance|
+          allow(instance).to receive(:render_in).and_return('diff-file-header-with-env')
+        end
+
+        result = render_component(environment: environment)
+
+        expect(result.to_html).to include('diff-file-header-with-env')
+      end
+    end
   end
 
   def render_component(**args, &block)
diff --git a/spec/components/rapid_diffs/diff_file_header_component_spec.rb b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
index 0491f88a77fde3..fa166a5b885c39 100644
--- a/spec/components/rapid_diffs/diff_file_header_component_spec.rb
+++ b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
@@ -190,6 +190,97 @@
         expect(item).not_to have_key('position')
       end
     end
+
+    context 'with environment' do
+      let(:project) { diff_file.repository.project }
+      let(:environment) { build(:environment, project: project, external_url: 'https://test.example.com') }
+      let(:environment_path) { "https://test.example.com/#{diff_file.new_path}" }
+
+      before do
+        allow(environment).to receive(:formatted_external_url).and_return('test.example.com')
+        allow(environment).to receive(:external_url_for)
+                                .with(diff_file.new_path, content_sha)
+                                .and_return(environment_path)
+      end
+
+      it 'renders "View on environment" menu item' do
+        render_component(environment: environment)
+
+        options_menu_items = Gitlab::Json.parse(page.find('script', visible: false).text)
+
+        view_on_env_item = options_menu_items.find { |item| item['text']&.include?('View on') }
+
+        expect(view_on_env_item).not_to be_nil
+        expect(view_on_env_item['text']).to include('test.example.com')
+        expect(view_on_env_item['href']).to eq(environment_path)
+        expect(view_on_env_item['extraAttrs']['target']).to eq('_blank')
+        expect(view_on_env_item['extraAttrs']['rel']).to eq('noopener noreferrer')
+      end
+
+      it 'uses correct file path and SHA when calling external_url_for' do
+        expect(environment).to receive(:external_url_for)
+                                 .with(diff_file.new_path, content_sha)
+                                 .and_return(environment_path)
+
+        render_component(environment: environment)
+      end
+
+      context 'when file is renamed' do
+        before do
+          allow(diff_file).to receive(:new_path).and_return('new/file/path.rb')
+          allow(diff_file).to receive(:old_path).and_return('old/file/path.rb')
+        end
+
+        it 'uses new_path for environment URL generation' do
+          expect(environment).to receive(:external_url_for)
+                                   .with(diff_file.new_path, content_sha)
+                                   .once
+                                   .and_return(environment_path)
+
+          render_component(environment: environment)
+        end
+      end
+
+      context 'when environment has no route map for the file' do
+        before do
+          allow(environment).to receive(:external_url_for)
+                                  .with(diff_file.new_path, content_sha)
+                                  .and_return(nil)
+        end
+
+        it 'does not render "View on environment" menu item' do
+          render_component(environment: environment)
+
+          options_menu_items = Gitlab::Json.parse(page.find('script', visible: false).text)
+
+          view_on_env_item = options_menu_items.find { |item| item['text']&.include?('View on') }
+
+          expect(view_on_env_item).to be_nil
+        end
+      end
+    end
+
+    context 'without environment' do
+      it 'does not render "View on environment" menu item when environment is nil' do
+        render_component(environment: nil)
+
+        options_menu_items = Gitlab::Json.parse(page.find('script', visible: false).text)
+
+        view_on_env_item = options_menu_items.find { |item| item['text']&.include?('View on') }
+
+        expect(view_on_env_item).to be_nil
+      end
+
+      it 'does not render "View on environment" menu item when environment is not provided' do
+        render_component
+
+        options_menu_items = Gitlab::Json.parse(page.find('script', visible: false).text)
+
+        view_on_env_item = options_menu_items.find { |item| item['text']&.include?('View on') }
+
+        expect(view_on_env_item).to be_nil
+      end
+    end
   end
 
   def create_instance(**args)
diff --git a/spec/controllers/concerns/rapid_diffs/resource_spec.rb b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
index 0b025499769518..e49bb100a332f7 100644
--- a/spec/controllers/concerns/rapid_diffs/resource_spec.rb
+++ b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
@@ -67,6 +67,27 @@ def with_custom_diff_options
 
       controller.new.call_diff_file_component(args)
     end
+
+    context 'when environment is nil' do
+      let(:environment) { nil }
+
+      it 'creates a DiffFileComponent with nil environment' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
+                                                     .with(**base_args, environment: nil)
+
+        controller.diff_file_component(base_args)
+      end
+
+      it 'passes through all base_args to the component' do
+        additional_args = { parallel_view: true, some_option: 'value' }
+        full_args = base_args.merge(additional_args)
+
+        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
+                                                     .with(**full_args, environment: environment)
+
+        controller.diff_file_component(full_args)
+      end
+    end
   end
 
   describe '#find_diff_file' do
@@ -88,4 +109,20 @@ def with_custom_diff_options
       expect(controller_instance.call_find_diff_file(extra_options, old_path, new_path)).to eq(diff_file)
     end
   end
+
+  describe '#environment' do
+    context 'when environment is set' do
+      it 'returns the environment' do
+        expect(controller.environment).to eq(environment)
+      end
+    end
+
+    context 'when environment is not set' do
+      let(:environment) { nil }
+
+      it 'returns nil' do
+        expect(controller.environment).to be_nil
+      end
+    end
+  end
 end
diff --git a/spec/controllers/concerns/rapid_diffs/streaming_resource_spec.rb b/spec/controllers/concerns/rapid_diffs/streaming_resource_spec.rb
index f1db1e84dcee1b..38cf553a5d0d20 100644
--- a/spec/controllers/concerns/rapid_diffs/streaming_resource_spec.rb
+++ b/spec/controllers/concerns/rapid_diffs/streaming_resource_spec.rb
@@ -49,6 +49,150 @@ def diff_options
     end
   end
 
+  describe '#environment' do
+    let(:controller_instance) { controller.new }
+
+    context 'when environment is set' do
+      let(:environment) { build(:environment) }
+
+      before do
+        controller_instance.instance_variable_set(:@environment, environment)
+      end
+
+      it 'returns the environment' do
+        expect(controller_instance.send(:environment)).to eq(environment)
+      end
+    end
+
+    context 'when environment is not set' do
+      it 'returns nil' do
+        expect(controller_instance.send(:environment)).to be_nil
+      end
+    end
+  end
+
+  describe '#diff_file_component' do
+    let(:controller_instance) { controller.new }
+    let(:diff_file) { build(:diff_file) }
+
+    before do
+      allow(controller_instance).to receive_message_chain(:helpers, :diff_view).and_return(:inline)
+    end
+
+    context 'when environment is nil' do
+      it 'creates a DiffFileComponent with nil environment' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
+                                                     .with(
+                                                       diff_file: diff_file,
+                                                       parallel_view: false,
+                                                       environment: nil
+                                                     )
+
+        controller_instance.send(:diff_file_component, diff_file)
+      end
+    end
+
+    context 'when environment is set' do
+      let(:environment) { build(:environment) }
+
+      before do
+        controller_instance.instance_variable_set(:@environment, environment)
+      end
+
+      it 'creates a DiffFileComponent with the environment' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
+                                                     .with(
+                                                       diff_file: diff_file,
+                                                       parallel_view: false,
+                                                       environment: environment
+                                                     )
+
+        controller_instance.send(:diff_file_component, diff_file)
+      end
+    end
+
+    context 'when view is parallel' do
+      let(:environment) { build(:environment) }
+
+      before do
+        allow(controller_instance).to receive_message_chain(:helpers, :diff_view).and_return(:parallel)
+        controller_instance.instance_variable_set(:@environment, environment)
+      end
+
+      it 'creates a DiffFileComponent with parallel_view: true' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
+                                                     .with(
+                                                       diff_file: diff_file,
+                                                       parallel_view: true,
+                                                       environment: environment
+                                                     )
+
+        controller_instance.send(:diff_file_component, diff_file)
+      end
+    end
+  end
+
+  describe '#diff_files_collection' do
+    let(:controller_instance) { controller.new }
+    let(:diff_files) { [build(:diff_file), build(:diff_file)] }
+
+    before do
+      allow(controller_instance).to receive_message_chain(:helpers, :diff_view).and_return(:inline)
+    end
+
+    context 'when environment is nil' do
+      it 'creates a DiffFileComponent collection with nil environment' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:with_collection)
+                                                     .with(
+                                                       diff_files,
+                                                       parallel_view: false,
+                                                       environment: nil
+                                                     )
+
+        controller_instance.send(:diff_files_collection, diff_files)
+      end
+    end
+
+    context 'when environment is set' do
+      let(:environment) { build(:environment) }
+
+      before do
+        controller_instance.instance_variable_set(:@environment, environment)
+      end
+
+      it 'creates a DiffFileComponent collection with the environment' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:with_collection)
+                                                     .with(
+                                                       diff_files,
+                                                       parallel_view: false,
+                                                       environment: environment
+                                                     )
+
+        controller_instance.send(:diff_files_collection, diff_files)
+      end
+    end
+
+    context 'when view is parallel' do
+      let(:environment) { build(:environment) }
+
+      before do
+        allow(controller_instance).to receive_message_chain(:helpers, :diff_view).and_return(:parallel)
+        controller_instance.instance_variable_set(:@environment, environment)
+      end
+
+      it 'creates a DiffFileComponent collection with parallel_view: true' do
+        expect(::RapidDiffs::DiffFileComponent).to receive(:with_collection)
+                                                     .with(
+                                                       diff_files,
+                                                       parallel_view: true,
+                                                       environment: environment
+                                                     )
+
+        controller_instance.send(:diff_files_collection, diff_files)
+      end
+    end
+  end
+
   describe '#diffs' do
     let(:controller_instance) { controller.new }
     let(:mock_resource) { instance_double(::Commit) }
diff --git a/spec/features/projects/view_on_env_spec.rb b/spec/features/projects/view_on_env_spec.rb
index a790a64ee8c5e8..cb262c6e8b9a3c 100644
--- a/spec/features/projects/view_on_env_spec.rb
+++ b/spec/features/projects/view_on_env_spec.rb
@@ -67,11 +67,11 @@
           end
         end
 
-        context 'when visiting a comparison for the commit' do
+        context 'when visiting the commit' do
           before do
             sign_in(user)
 
-            visit project_compare_path(project, from: 'master', to: sha)
+            visit project_commit_path(project, sha)
 
             wait_for_requests
           end
@@ -82,26 +82,68 @@
         end
       end
 
-      context 'when visiting a blob on the branch' do
+      context 'with rapid diffs' do
         before do
-          sign_in(user)
+          stub_feature_flags(rapid_diffs_on_compare_show: true)
+        end
 
-          visit project_blob_path(project, File.join(branch_name, file_path))
+        context 'when visiting a comparison for the branch' do
+          before do
+            sign_in(user)
 
-          wait_for_requests
+            visit project_compare_path(project, from: 'master', to: branch_name)
+
+            wait_for_requests
+          end
+
+          it 'has a "View on env" button in the file header menu' do
+            diff_file = all_by_testid('rd-diff-file').find do |file|
+              file.has_text?(file_path)
+            end
+            diff_file.find('button[data-click="toggleOptionsMenu"]').click
+
+            expect(page).to have_link(
+              'View on feature.review.example.com',
+              href: 'http://feature.review.example.com/ruby/feature'
+            )
+          end
         end
 
-        it 'has a "View on env" button' do
-          click_button 'File actions'
-          expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
+        context 'when visiting the commit' do
+          before do
+            sign_in(user)
+
+            visit project_commit_path(project, sha, rapid_diffs: true)
+
+            wait_for_requests
+          end
+
+          it 'has a "View on env" button' do
+            first_file = find_by_testid('rd-diff-file')
+            first_file.find('button[data-click="toggleOptionsMenu"]').click
+
+            expect(page).to have_link(
+              'View on feature.review.example.com',
+              href: 'http://feature.review.example.com/ruby/feature'
+            )
+          end
+
+          it 'opens the environment URL in a new tab' do
+            first_file = find_by_testid('rd-diff-file')
+            first_file.find('button[data-click="toggleOptionsMenu"]').click
+
+            link = page.find_link('View on feature.review.example.com')
+            expect(link[:target]).to eq('_blank')
+            expect(link[:rel]).to include('noopener')
+          end
         end
       end
 
-      context 'when visiting a blob on the commit' do
+      context 'when visiting a blob on the branch' do
         before do
           sign_in(user)
 
-          visit project_blob_path(project, File.join(sha, file_path))
+          visit project_blob_path(project, File.join(branch_name, file_path))
 
           wait_for_requests
         end
@@ -112,16 +154,17 @@
         end
       end
 
-      context 'when visiting the commit' do
+      context 'when visiting a blob on the commit' do
         before do
           sign_in(user)
 
-          visit project_commit_path(project, sha)
+          visit project_blob_path(project, File.join(sha, file_path))
 
           wait_for_requests
         end
 
         it 'has a "View on env" button' do
+          click_button 'File actions'
           expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
         end
       end
diff --git a/spec/presenters/rapid_diffs/base_presenter_spec.rb b/spec/presenters/rapid_diffs/base_presenter_spec.rb
index 2b0fc202fa44bf..0a8c02b6026671 100644
--- a/spec/presenters/rapid_diffs/base_presenter_spec.rb
+++ b/spec/presenters/rapid_diffs/base_presenter_spec.rb
@@ -5,6 +5,48 @@
 RSpec.describe RapidDiffs::BasePresenter, feature_category: :source_code_management do
   subject(:presenter) { described_class.new(Class.new, :inline, {}) }
 
+  describe '#initialize' do
+    context 'when environment is provided' do
+      let(:environment) { build(:environment) }
+      let(:presenter_with_env) { described_class.new(Class.new, :inline, {}, nil, environment) }
+
+      it 'sets the environment' do
+        expect(presenter_with_env.environment).to eq(environment)
+      end
+    end
+
+    context 'when environment is not provided' do
+      it 'sets environment to nil' do
+        expect(presenter.environment).to be_nil
+      end
+    end
+
+    context 'when environment is explicitly nil' do
+      let(:presenter_with_nil_env) { described_class.new(Class.new, :inline, {}, nil, nil) }
+
+      it 'sets environment to nil' do
+        expect(presenter_with_nil_env.environment).to be_nil
+      end
+    end
+  end
+
+  describe '#environment' do
+    context 'when environment is set' do
+      let(:environment) { build(:environment) }
+      let(:presenter_with_env) { described_class.new(Class.new, :inline, {}, nil, environment) }
+
+      it 'returns the environment' do
+        expect(presenter_with_env.environment).to eq(environment)
+      end
+    end
+
+    context 'when environment is not set' do
+      it 'returns nil' do
+        expect(presenter.environment).to be_nil
+      end
+    end
+  end
+
   describe 'abstract methods' do
     it 'raises a NotImplementedError for #diffs_stats_endpoint' do
       expect { presenter.diffs_stats_endpoint }.to raise_error(NotImplementedError)
-- 
GitLab


From 80763b7e698dc22c79296cfd36e65228f99b421c Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Wed, 12 Nov 2025 23:23:21 -0500
Subject: [PATCH 2/8] Fix view environment in compare page

---
 app/controllers/projects/compare_diffs_stream_controller.rb | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/app/controllers/projects/compare_diffs_stream_controller.rb b/app/controllers/projects/compare_diffs_stream_controller.rb
index f73e9b91c5059f..ccfa120ebcfe27 100644
--- a/app/controllers/projects/compare_diffs_stream_controller.rb
+++ b/app/controllers/projects/compare_diffs_stream_controller.rb
@@ -4,6 +4,8 @@ module Projects
   class CompareDiffsStreamController < Projects::CompareController
     include RapidDiffs::StreamingResource
 
+    before_action :define_environment
+
     private
 
     def resource
-- 
GitLab


From c06f0ca3e8b5fd6fc91891fcae68c76ae566309c Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Thu, 13 Nov 2025 15:47:56 -0500
Subject: [PATCH 3/8] Fix test failures

# Conflicts:
#	spec/components/rapid_diffs/commit_app_component_spec.rb
---
 .../rapid_diffs/app_component_spec.rb         |  1 +
 .../rapid_diffs/commit_app_component_spec.rb  |  4 ++-
 .../concerns/rapid_diffs/resource_spec.rb     | 33 ++++++++++---------
 3 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/spec/components/rapid_diffs/app_component_spec.rb b/spec/components/rapid_diffs/app_component_spec.rb
index 354296e7f53f5b..5607b8a9b8cca8 100644
--- a/spec/components/rapid_diffs/app_component_spec.rb
+++ b/spec/components/rapid_diffs/app_component_spec.rb
@@ -27,6 +27,7 @@
       diff_files_endpoint: diff_files_endpoint,
       diff_file_endpoint: diff_file_endpoint,
       should_sort_metadata_files?: should_sort_metadata_files,
+      environment: nil,
       lazy?: lazy
     )
   end
diff --git a/spec/components/rapid_diffs/commit_app_component_spec.rb b/spec/components/rapid_diffs/commit_app_component_spec.rb
index 969298d6d35028..589897997ba1a1 100644
--- a/spec/components/rapid_diffs/commit_app_component_spec.rb
+++ b/spec/components/rapid_diffs/commit_app_component_spec.rb
@@ -23,7 +23,9 @@
       register_path: register_path,
       sign_in_path: sign_in_path,
       report_abuse_path: report_abuse_path,
-      markdown_docs_path: markdown_docs_path
+      markdown_docs_path: markdown_docs_path,
+      environment: nil,
+      lazy?: lazy
     )
   end
 
diff --git a/spec/controllers/concerns/rapid_diffs/resource_spec.rb b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
index e49bb100a332f7..023226e966f2e8 100644
--- a/spec/controllers/concerns/rapid_diffs/resource_spec.rb
+++ b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
@@ -61,31 +61,32 @@ def with_custom_diff_options
 
   describe '#diff_file_component' do
     it 'initializes a DiffFileComponent with the given arguments' do
-      args = { parallel_view: :parallel }
+      args = { diff_file: instance_double(Gitlab::Git::Diff), parallel_view: :parallel }
 
-      expect(RapidDiffs::DiffFileComponent).to receive(:new).with(**args)
+      expect(RapidDiffs::DiffFileComponent).to receive(:new).with(**args, environment: nil)
 
       controller.new.call_diff_file_component(args)
     end
 
     context 'when environment is nil' do
-      let(:environment) { nil }
-
       it 'creates a DiffFileComponent with nil environment' do
+        base_args = { diff_file: instance_double(Gitlab::Git::Diff) }
+
         expect(::RapidDiffs::DiffFileComponent).to receive(:new)
                                                      .with(**base_args, environment: nil)
 
-        controller.diff_file_component(base_args)
+        controller.new.call_diff_file_component(base_args)
       end
 
       it 'passes through all base_args to the component' do
+        base_args = { diff_file: instance_double(Gitlab::Git::Diff) }
         additional_args = { parallel_view: true, some_option: 'value' }
         full_args = base_args.merge(additional_args)
 
         expect(::RapidDiffs::DiffFileComponent).to receive(:new)
-                                                     .with(**full_args, environment: environment)
+                                                     .with(**full_args, environment: nil)
 
-        controller.diff_file_component(full_args)
+        controller.new.call_diff_file_component(full_args)
       end
     end
   end
@@ -111,17 +112,19 @@ def with_custom_diff_options
   end
 
   describe '#environment' do
-    context 'when environment is set' do
-      it 'returns the environment' do
-        expect(controller.environment).to eq(environment)
-      end
+    it 'returns nil by default' do
+      controller_instance = controller.new
+
+      expect(controller_instance.send(:environment)).to be_nil
     end
 
-    context 'when environment is not set' do
-      let(:environment) { nil }
+    context 'when environment instance variable is set' do
+      it 'returns the environment' do
+        controller_instance = controller.new
+        environment = instance_double(Environment)
+        controller_instance.instance_variable_set(:@environment, environment)
 
-      it 'returns nil' do
-        expect(controller.environment).to be_nil
+        expect(controller_instance.send(:environment)).to eq(environment)
       end
     end
   end
-- 
GitLab


From f3fbad6b3be82fbbedbca07120b02e56c72f2ee2 Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Mon, 24 Nov 2025 15:27:12 -0500
Subject: [PATCH 4/8] Address test comments

---
 .../rapid_diffs/diff_file_header_component.rb |  2 +-
 .../diff_file_header_component_spec.rb        | 19 +++-----
 .../concerns/rapid_diffs/resource_spec.rb     | 11 -----
 spec/features/projects/view_on_env_spec.rb    | 38 ++++++----------
 .../rapid_diffs/base_presenter_spec.rb        | 44 ++++---------------
 5 files changed, 29 insertions(+), 85 deletions(-)

diff --git a/app/components/rapid_diffs/diff_file_header_component.rb b/app/components/rapid_diffs/diff_file_header_component.rb
index ed95f050b23688..4406e3da777f8e 100644
--- a/app/components/rapid_diffs/diff_file_header_component.rb
+++ b/app/components/rapid_diffs/diff_file_header_component.rb
@@ -37,7 +37,7 @@ def copy_path_button
     end
 
     def menu_items
-      @menu_items ||= [
+      [
         view_file_menu_item,
         view_on_environment_menu_item,
         *@additional_menu_items
diff --git a/spec/components/rapid_diffs/diff_file_header_component_spec.rb b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
index fa166a5b885c39..a1fbc4e6ad1647 100644
--- a/spec/components/rapid_diffs/diff_file_header_component_spec.rb
+++ b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
@@ -217,27 +217,20 @@
         expect(view_on_env_item['extraAttrs']['rel']).to eq('noopener noreferrer')
       end
 
-      it 'uses correct file path and SHA when calling external_url_for' do
-        expect(environment).to receive(:external_url_for)
-                                 .with(diff_file.new_path, content_sha)
-                                 .and_return(environment_path)
-
-        render_component(environment: environment)
-      end
-
       context 'when file is renamed' do
         before do
           allow(diff_file).to receive(:new_path).and_return('new/file/path.rb')
           allow(diff_file).to receive(:old_path).and_return('old/file/path.rb')
+          allow(environment).to receive(:external_url_for) do |path, _sha|
+            path == diff_file.new_path ? environment_path : nil
+          end
         end
 
         it 'uses new_path for environment URL generation' do
-          expect(environment).to receive(:external_url_for)
-                                   .with(diff_file.new_path, content_sha)
-                                   .once
-                                   .and_return(environment_path)
-
           render_component(environment: environment)
+
+          expect(page).to have_content('View on test.example.com')
+          expect(page).to have_content(environment_path)
         end
       end
 
diff --git a/spec/controllers/concerns/rapid_diffs/resource_spec.rb b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
index 023226e966f2e8..775d0d8a587b6b 100644
--- a/spec/controllers/concerns/rapid_diffs/resource_spec.rb
+++ b/spec/controllers/concerns/rapid_diffs/resource_spec.rb
@@ -77,17 +77,6 @@ def with_custom_diff_options
 
         controller.new.call_diff_file_component(base_args)
       end
-
-      it 'passes through all base_args to the component' do
-        base_args = { diff_file: instance_double(Gitlab::Git::Diff) }
-        additional_args = { parallel_view: true, some_option: 'value' }
-        full_args = base_args.merge(additional_args)
-
-        expect(::RapidDiffs::DiffFileComponent).to receive(:new)
-                                                     .with(**full_args, environment: nil)
-
-        controller.new.call_diff_file_component(full_args)
-      end
     end
   end
 
diff --git a/spec/features/projects/view_on_env_spec.rb b/spec/features/projects/view_on_env_spec.rb
index cb262c6e8b9a3c..0064b9052dcf13 100644
--- a/spec/features/projects/view_on_env_spec.rb
+++ b/spec/features/projects/view_on_env_spec.rb
@@ -51,31 +51,19 @@
       context 'with legacy diffs' do
         before do
           stub_feature_flags(rapid_diffs_on_compare_show: false)
+          sign_in(user)
+          visit page_path
+          wait_for_requests
         end
 
-        context 'when visiting a comparison for the branch' do
-          before do
-            sign_in(user)
-
-            visit project_compare_path(project, from: 'master', to: branch_name)
-
-            wait_for_requests
-          end
-
-          it 'has a "View on env" button' do
-            expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
-          end
+        where(:page_path) do
+          [
+            lazy { project_compare_path(project, from: 'master', to: branch_name) },
+            lazy { project_commit_path(project, sha) }
+          ]
         end
 
-        context 'when visiting the commit' do
-          before do
-            sign_in(user)
-
-            visit project_commit_path(project, sha)
-
-            wait_for_requests
-          end
-
+        with_them do
           it 'has a "View on env" button' do
             expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
           end
@@ -100,7 +88,7 @@
             diff_file = all_by_testid('rd-diff-file').find do |file|
               file.has_text?(file_path)
             end
-            diff_file.find('button[data-click="toggleOptionsMenu"]').click
+            diff_file.find('button:has([data-testid="ellipsis_v-icon"])').click
 
             expect(page).to have_link(
               'View on feature.review.example.com',
@@ -118,9 +106,9 @@
             wait_for_requests
           end
 
-          it 'has a "View on env" button' do
+          it 'has a "View on env" button in the file header menu' do
             first_file = find_by_testid('rd-diff-file')
-            first_file.find('button[data-click="toggleOptionsMenu"]').click
+            first_file.find('button:has([data-testid="ellipsis_v-icon"])').click
 
             expect(page).to have_link(
               'View on feature.review.example.com',
@@ -130,7 +118,7 @@
 
           it 'opens the environment URL in a new tab' do
             first_file = find_by_testid('rd-diff-file')
-            first_file.find('button[data-click="toggleOptionsMenu"]').click
+            first_file.find('button:has([data-testid="ellipsis_v-icon"])').click
 
             link = page.find_link('View on feature.review.example.com')
             expect(link[:target]).to eq('_blank')
diff --git a/spec/presenters/rapid_diffs/base_presenter_spec.rb b/spec/presenters/rapid_diffs/base_presenter_spec.rb
index 0a8c02b6026671..604e4a84e4bfcd 100644
--- a/spec/presenters/rapid_diffs/base_presenter_spec.rb
+++ b/spec/presenters/rapid_diffs/base_presenter_spec.rb
@@ -3,47 +3,21 @@
 require 'spec_helper'
 
 RSpec.describe RapidDiffs::BasePresenter, feature_category: :source_code_management do
-  subject(:presenter) { described_class.new(Class.new, :inline, {}) }
+  let(:diff_view) { :inline }
+  let(:diff_options) { {} }
+  let(:environment) { nil }
 
-  describe '#initialize' do
-    context 'when environment is provided' do
-      let(:environment) { build(:environment) }
-      let(:presenter_with_env) { described_class.new(Class.new, :inline, {}, nil, environment) }
-
-      it 'sets the environment' do
-        expect(presenter_with_env.environment).to eq(environment)
-      end
-    end
+  subject(:presenter) { described_class.new(Class.new, diff_view, diff_options, nil, environment) }
 
-    context 'when environment is not provided' do
-      it 'sets environment to nil' do
-        expect(presenter.environment).to be_nil
-      end
-    end
+  describe '#environment' do
+    subject(:method) { presenter.environment }
 
-    context 'when environment is explicitly nil' do
-      let(:presenter_with_nil_env) { described_class.new(Class.new, :inline, {}, nil, nil) }
+    it { is_expected.to be_nil }
 
-      it 'sets environment to nil' do
-        expect(presenter_with_nil_env.environment).to be_nil
-      end
-    end
-  end
-
-  describe '#environment' do
-    context 'when environment is set' do
+    context 'when environment is provided' do
       let(:environment) { build(:environment) }
-      let(:presenter_with_env) { described_class.new(Class.new, :inline, {}, nil, environment) }
-
-      it 'returns the environment' do
-        expect(presenter_with_env.environment).to eq(environment)
-      end
-    end
 
-    context 'when environment is not set' do
-      it 'returns nil' do
-        expect(presenter.environment).to be_nil
-      end
+      it { is_expected.to eq(environment) }
     end
   end
 
-- 
GitLab


From 34a1b36deb2c4473f938febe64c9f7c0692e5c6d Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Mon, 24 Nov 2025 15:46:05 -0500
Subject: [PATCH 5/8] Remove `rapid_diffs` from `before_action`

---
 app/controllers/projects/commit_controller.rb | 23 +++++++++++--------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/app/controllers/projects/commit_controller.rb b/app/controllers/projects/commit_controller.rb
index 9cfa9dafe86cc1..4feeb4d6ab488b 100644
--- a/app/controllers/projects/commit_controller.rb
+++ b/app/controllers/projects/commit_controller.rb
@@ -16,9 +16,9 @@ class Projects::CommitController < Projects::ApplicationController
   before_action :authorize_read_code!
   before_action :authorize_read_pipeline!, only: [:pipelines]
   before_action :commit
-  before_action :define_commit_vars, only: [
-    :show, :diff_for_path, :diff_files, :pipelines, :merge_requests, :rapid_diffs
-  ]
+  before_action :define_commit_vars, only: [:show, :diff_for_path, :diff_files, :pipelines, :merge_requests]
+  before_action :define_environment,
+    only: [:show, :rapid_diffs, :diff_for_path, :diff_files, :pipelines, :merge_requests]
   before_action :define_commit_box_vars, only: [:show, :pipelines, :rapid_diffs]
   before_action :define_note_vars, only: [:show, :diff_for_path, :diff_files, :discussions]
   before_action :authorize_edit_tree!, only: [:revert, :cherry_pick]
@@ -165,6 +165,15 @@ def cherry_pick
     )
   end
 
+  def define_environment
+    @environment ||= ::Environments::EnvironmentsByDeploymentsFinder.new(
+      @project,
+      current_user,
+      commit: @commit,
+      find_latest: true
+    ).execute.last
+  end
+
   def rapid_diffs
     return render_404 unless ::Feature.enabled?(:rapid_diffs_on_commit_show, current_user, type: :wip)
 
@@ -175,7 +184,7 @@ def rapid_diffs
       commit_diff_options,
       nil,
       current_user,
-      @environment
+      define_environment
     )
 
     show
@@ -227,12 +236,6 @@ def define_commit_vars
     return git_not_found! unless commit
 
     @diffs = commit.diffs(commit_diff_options)
-    @environment = ::Environments::EnvironmentsByDeploymentsFinder.new(
-      @project,
-      current_user,
-      commit: @commit,
-      find_latest: true
-    ).execute.last
   end
 
   # rubocop: disable CodeReuse/ActiveRecord
-- 
GitLab


From d590ecd19882c1b4d3abf7ab4e5c2da7a8128bc2 Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Fri, 28 Nov 2025 11:36:26 -0500
Subject: [PATCH 6/8] Address Gavin's comments

- Add `:define_environment` to `CommitDiffsStreamController`
- Add request tests for `CommitDiffsStreamController` and
 `CompareDiffsStreamController`
---
 .../commit_diffs_stream_controller.rb         |  2 +
 .../diff_file_header_component_spec.rb        | 10 -----
 .../commit_diffs_stream_controller_spec.rb    | 42 +++++++++++++++++++
 .../compare_diffs_stream_controller_spec.rb   | 38 +++++++++++++++++
 4 files changed, 82 insertions(+), 10 deletions(-)

diff --git a/app/controllers/projects/commit_diffs_stream_controller.rb b/app/controllers/projects/commit_diffs_stream_controller.rb
index 387511885a3515..7c584150547bdf 100644
--- a/app/controllers/projects/commit_diffs_stream_controller.rb
+++ b/app/controllers/projects/commit_diffs_stream_controller.rb
@@ -4,6 +4,8 @@ module Projects
   class CommitDiffsStreamController < Projects::CommitController
     include RapidDiffs::StreamingResource
 
+    before_action :define_environment
+
     private
 
     def resource
diff --git a/spec/components/rapid_diffs/diff_file_header_component_spec.rb b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
index a1fbc4e6ad1647..1c07e2309feefa 100644
--- a/spec/components/rapid_diffs/diff_file_header_component_spec.rb
+++ b/spec/components/rapid_diffs/diff_file_header_component_spec.rb
@@ -263,16 +263,6 @@
 
         expect(view_on_env_item).to be_nil
       end
-
-      it 'does not render "View on environment" menu item when environment is not provided' do
-        render_component
-
-        options_menu_items = Gitlab::Json.parse(page.find('script', visible: false).text)
-
-        view_on_env_item = options_menu_items.find { |item| item['text']&.include?('View on') }
-
-        expect(view_on_env_item).to be_nil
-      end
     end
   end
 
diff --git a/spec/requests/projects/commit_diffs_stream_controller_spec.rb b/spec/requests/projects/commit_diffs_stream_controller_spec.rb
index e636f7b34b9d80..79a561c3abd5f2 100644
--- a/spec/requests/projects/commit_diffs_stream_controller_spec.rb
+++ b/spec/requests/projects/commit_diffs_stream_controller_spec.rb
@@ -5,6 +5,7 @@
 RSpec.describe 'Commit diffs stream', feature_category: :source_code_management do
   let_it_be(:project) { create(:project, :public, :repository) }
   let_it_be(:user) { create(:user, maintainer_of: project) }
+
   let(:commit_with_two_diffs) { project.commit("874797c3a73b60d2187ed6e2fcabd289ff75171e") }
   let(:offset) { 0 }
   let(:diff_files) { commit_with_two_diffs.diffs.diff_files }
@@ -38,5 +39,46 @@ def go(**extra_params)
     include_examples 'diffs stream tests'
 
     include_examples 'with diffs_blobs param'
+
+    context 'with environment' do
+      let(:environment) { create(:environment, project: project, external_url: 'https://example.com') }
+
+      before do
+        create(
+          :deployment, :success, environment: environment,
+          project: project, sha: commit_with_two_diffs.sha
+        )
+
+        allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
+          allow(finder).to receive(:execute).and_return([environment])
+        end
+
+        allow(project).to receive(:public_path_for_source_path).and_return('public/file.html')
+      end
+
+      it 'includes environment link in response' do
+        go
+
+        expect(response.body).to include('View on')
+        expect(response.body).to include(environment.formatted_external_url)
+      end
+    end
+
+    context 'without environment' do
+      before do
+        create(:deployment, :success, environment:
+          create(:environment, project: project), project: project, sha: commit_with_two_diffs.sha)
+
+        allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
+          allow(finder).to receive(:execute).and_return([])
+        end
+      end
+
+      it 'does not include environment link in response' do
+        go
+
+        expect(response.body).not_to include('View on')
+      end
+    end
   end
 end
diff --git a/spec/requests/projects/compare_diffs_stream_controller_spec.rb b/spec/requests/projects/compare_diffs_stream_controller_spec.rb
index c12b2e859acd72..a64c4968b814e5 100644
--- a/spec/requests/projects/compare_diffs_stream_controller_spec.rb
+++ b/spec/requests/projects/compare_diffs_stream_controller_spec.rb
@@ -53,5 +53,43 @@ def go(**extra_params)
     include_examples 'diffs stream tests'
 
     include_examples 'with diffs_blobs param'
+
+    context 'with environment' do
+      let(:environment) { create(:environment, project: project, external_url: 'https://example.com') }
+
+      before do
+        create(:deployment, :success, environment: environment, project: project, sha: compare.head_commit_sha)
+
+        allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
+          allow(finder).to receive(:execute).and_return([environment])
+        end
+
+        allow(project).to receive(:public_path_for_source_path).and_return('public/file.html')
+      end
+
+      it 'includes environment link in response' do
+        go
+
+        expect(response.body).to include('View on')
+        expect(response.body).to include(environment.formatted_external_url)
+      end
+    end
+
+    context 'without environment' do
+      before do
+        create(:deployment, :success, environment: create(:environment, project: project),
+          project: project, sha: compare.head_commit_sha)
+
+        allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
+          allow(finder).to receive(:execute).and_return([])
+        end
+      end
+
+      it 'does not include environment link in response' do
+        go
+
+        expect(response.body).not_to include('View on')
+      end
+    end
   end
 end
-- 
GitLab


From 778f4ba8a65679575cbfacaa717accdf961497f8 Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Fri, 28 Nov 2025 11:44:10 -0500
Subject: [PATCH 7/8] Move `define_environment` into private section

---
 app/controllers/projects/commit_controller.rb | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/app/controllers/projects/commit_controller.rb b/app/controllers/projects/commit_controller.rb
index 4feeb4d6ab488b..42b0e94fef767c 100644
--- a/app/controllers/projects/commit_controller.rb
+++ b/app/controllers/projects/commit_controller.rb
@@ -165,15 +165,6 @@ def cherry_pick
     )
   end
 
-  def define_environment
-    @environment ||= ::Environments::EnvironmentsByDeploymentsFinder.new(
-      @project,
-      current_user,
-      commit: @commit,
-      find_latest: true
-    ).execute.last
-  end
-
   def rapid_diffs
     return render_404 unless ::Feature.enabled?(:rapid_diffs_on_commit_show, current_user, type: :wip)
 
@@ -324,6 +315,15 @@ def complete_diff_path
   def email_format_path
     project_commit_path(project, commit, format: :patch)
   end
+
+  def define_environment
+    @environment ||= ::Environments::EnvironmentsByDeploymentsFinder.new(
+      @project,
+      current_user,
+      commit: @commit,
+      find_latest: true
+    ).execute.last
+  end
 end
 
 Projects::CommitController.prepend_mod_with('Projects::CommitController')
-- 
GitLab


From 35575d9fd103295fd92d089e028558cabef0250b Mon Sep 17 00:00:00 2001
From: Chaoyue Zhao <czhao@gitlab.com>
Date: Mon, 1 Dec 2025 14:12:06 -0500
Subject: [PATCH 8/8] A few more comments!!

- Use `attr_reader`
- Clean up tests
---
 app/controllers/concerns/rapid_diffs/resource.rb |  4 +---
 .../concerns/rapid_diffs/streaming_resource.rb   |  4 +---
 app/controllers/projects/compare_controller.rb   |  3 +--
 .../rapid_diffs/commit_app_component_spec.rb     |  3 +--
 .../commit_diffs_stream_controller_spec.rb       | 16 ----------------
 5 files changed, 4 insertions(+), 26 deletions(-)

diff --git a/app/controllers/concerns/rapid_diffs/resource.rb b/app/controllers/concerns/rapid_diffs/resource.rb
index 4430146c46092e..f2f6964be8b85c 100644
--- a/app/controllers/concerns/rapid_diffs/resource.rb
+++ b/app/controllers/concerns/rapid_diffs/resource.rb
@@ -53,9 +53,7 @@ def diffs_resource(options = {})
       raise NotImplementedError
     end
 
-    def environment
-      @environment
-    end
+    attr_reader :environment
 
     def diff_file_component(base_args)
       ::RapidDiffs::DiffFileComponent.new(**base_args, environment: environment)
diff --git a/app/controllers/concerns/rapid_diffs/streaming_resource.rb b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
index 8abd471a3f237f..0f2f059bee9829 100644
--- a/app/controllers/concerns/rapid_diffs/streaming_resource.rb
+++ b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
@@ -85,9 +85,7 @@ def stream_diff_collection(options, view_context)
       response.stream.write(diff_files_collection(skipped).render_in(view_context)) unless skipped.empty?
     end
 
-    def environment
-      @environment
-    end
+    attr_reader :environment
 
     def diff_file_component(diff_file)
       ::RapidDiffs::DiffFileComponent.new(
diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 4f601cd466d210..289844bbb5147e 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -42,8 +42,7 @@ def show
         compare,
         diff_view,
         diff_options,
-        compare_params,
-        @environment
+        compare_params
       )
       return render action: :rapid_diffs
     end
diff --git a/spec/components/rapid_diffs/commit_app_component_spec.rb b/spec/components/rapid_diffs/commit_app_component_spec.rb
index 589897997ba1a1..90d4882332171e 100644
--- a/spec/components/rapid_diffs/commit_app_component_spec.rb
+++ b/spec/components/rapid_diffs/commit_app_component_spec.rb
@@ -24,8 +24,7 @@
       sign_in_path: sign_in_path,
       report_abuse_path: report_abuse_path,
       markdown_docs_path: markdown_docs_path,
-      environment: nil,
-      lazy?: lazy
+      environment: nil
     )
   end
 
diff --git a/spec/requests/projects/commit_diffs_stream_controller_spec.rb b/spec/requests/projects/commit_diffs_stream_controller_spec.rb
index 79a561c3abd5f2..3a505a3a465a08 100644
--- a/spec/requests/projects/commit_diffs_stream_controller_spec.rb
+++ b/spec/requests/projects/commit_diffs_stream_controller_spec.rb
@@ -5,7 +5,6 @@
 RSpec.describe 'Commit diffs stream', feature_category: :source_code_management do
   let_it_be(:project) { create(:project, :public, :repository) }
   let_it_be(:user) { create(:user, maintainer_of: project) }
-
   let(:commit_with_two_diffs) { project.commit("874797c3a73b60d2187ed6e2fcabd289ff75171e") }
   let(:offset) { 0 }
   let(:diff_files) { commit_with_two_diffs.diffs.diff_files }
@@ -44,11 +43,6 @@ def go(**extra_params)
       let(:environment) { create(:environment, project: project, external_url: 'https://example.com') }
 
       before do
-        create(
-          :deployment, :success, environment: environment,
-          project: project, sha: commit_with_two_diffs.sha
-        )
-
         allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
           allow(finder).to receive(:execute).and_return([environment])
         end
@@ -59,21 +53,11 @@ def go(**extra_params)
       it 'includes environment link in response' do
         go
 
-        expect(response.body).to include('View on')
         expect(response.body).to include(environment.formatted_external_url)
       end
     end
 
     context 'without environment' do
-      before do
-        create(:deployment, :success, environment:
-          create(:environment, project: project), project: project, sha: commit_with_two_diffs.sha)
-
-        allow_next_instance_of(Environments::EnvironmentsByDeploymentsFinder) do |finder|
-          allow(finder).to receive(:execute).and_return([])
-        end
-      end
-
       it 'does not include environment link in response' do
         go
 
-- 
GitLab