Change `UserAccess#project` to `#container`

This is the first step towards `UserAccess` being truly polymorphic. It
should accept any `HasRepository` instance.

app/controllers/concerns/checks_collaboration.rb

@@ -17,7 +17,7 @@ module ChecksCollaboration
   # used across multiple calls in the view
   def user_access(project)
     @user_access ||= {}
-    @user_access[project] ||= Gitlab::UserAccess.new(current_user, project: project)
+    @user_access[project] ||= Gitlab::UserAccess.new(current_user, container: project)
   end
   # rubocop:enable Gitlab/ModuleWithInstanceVariables
 end

app/controllers/projects/merge_requests_controller.rb

@@ -403,7 +403,7 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
     return access_denied! unless @merge_request.source_branch_exists?
 
     access_check = ::Gitlab::UserAccess
-      .new(current_user, project: @merge_request.source_project)
+      .new(current_user, container: @merge_request.source_project)
       .can_push_to_branch?(@merge_request.source_branch)
 
     access_denied! unless access_check

app/controllers/repositories/git_http_controller.rb

@@ -105,7 +105,7 @@ module Repositories
       access.check(git_command, Gitlab::GitAccess::ANY)
 
       if repo_type.project? && !container
-        @project = @container = access.project
+        @project = @container = access.container
       end
     end
 

app/models/merge_request.rb

@@ -1180,12 +1180,12 @@ class MergeRequest < ApplicationRecord
   end
 
   def can_be_merged_by?(user)
-    access = ::Gitlab::UserAccess.new(user, project: project)
+    access = ::Gitlab::UserAccess.new(user, container: project)
     access.can_update_branch?(target_branch)
   end
 
   def can_be_merged_via_command_line_by?(user)
-    access = ::Gitlab::UserAccess.new(user, project: project)
+    access = ::Gitlab::UserAccess.new(user, container: project)
     access.can_push_to_branch?(target_branch)
   end
 

app/policies/ci/build_policy.rb

@@ -3,7 +3,7 @@
 module Ci
   class BuildPolicy < CommitStatusPolicy
     condition(:protected_ref) do
-      access = ::Gitlab::UserAccess.new(@user, project: @subject.project)
+      access = ::Gitlab::UserAccess.new(@user, container: @subject.project)
 
       if @subject.tag?
         !access.can_create_tag?(@subject.ref)

app/policies/ci/pipeline_policy.rb

@@ -42,7 +42,7 @@ module Ci
     end
 
     def ref_protected?(user, project, tag, ref)
-      access = ::Gitlab::UserAccess.new(user, project: project)
+      access = ::Gitlab::UserAccess.new(user, container: project)
 
       if tag
         !access.can_create_tag?(ref)

app/policies/suggestion_policy.rb

@@ -4,7 +4,7 @@ class SuggestionPolicy < BasePolicy
   delegate { @subject.project }
 
   condition(:can_push_to_branch) do
-    Gitlab::UserAccess.new(@user, project: @subject.project).can_push_to_branch?(@subject.branch)
+    Gitlab::UserAccess.new(@user, container: @subject.project).can_push_to_branch?(@subject.branch)
   end
 
   rule { can_push_to_branch }.enable :apply_suggestion

app/presenters/merge_request_presenter.rb

@@ -179,7 +179,7 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
     return false unless source_branch_exists?
 
     !!::Gitlab::UserAccess
-      .new(current_user, project: source_project)
+      .new(current_user, container: source_project)
       .can_push_to_branch?(source_branch)
   end
 

app/services/ci/create_cross_project_pipeline_service.rb

@@ -98,7 +98,7 @@ module Ci
     end
 
     def can_update_branch?(target_ref)
-      ::Gitlab::UserAccess.new(current_user, project: downstream_project).can_update_branch?(target_ref)
+      ::Gitlab::UserAccess.new(current_user, container: downstream_project).can_update_branch?(target_ref)
     end
 
     def downstream_project

app/services/commits/create_service.rb

@@ -69,7 +69,7 @@ module Commits
     end
 
     def validate_permissions!
-      allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@branch_name)
+      allowed = ::Gitlab::UserAccess.new(current_user, container: project).can_push_to_branch?(@branch_name)
 
       unless allowed
         raise_error("You are not allowed to push into this branch")

app/services/merge_requests/conflicts/list_service.rb

@@ -8,7 +8,7 @@ module MergeRequests
       def can_be_resolved_by?(user)
         return false unless merge_request.source_project
 
-        access = ::Gitlab::UserAccess.new(user, project: merge_request.source_project)
+        access = ::Gitlab::UserAccess.new(user, container: merge_request.source_project)
         access.can_push_to_branch?(merge_request.source_branch)
       end
 

app/services/metrics/dashboard/clone_dashboard_service.rb

@@ -112,7 +112,7 @@ module Metrics
       end
 
       def push_authorized?
-        Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(branch)
+        Gitlab::UserAccess.new(current_user, container: project).can_push_to_branch?(branch)
       end
 
       def dashboard_template

app/services/metrics/dashboard/update_dashboard_service.rb

@@ -68,7 +68,7 @@ module Metrics
       end
 
       def push_authorized?
-        Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(branch)
+        Gitlab::UserAccess.new(current_user, container: project).can_push_to_branch?(branch)
       end
 
       def valid_branch_name?

ee/app/services/merge_requests/create_from_vulnerability_data_service.rb

@@ -92,7 +92,7 @@ module MergeRequests
     def can_create_merge_request?(source_branch)
       can?(@current_user, :create_merge_request_in, @project) &&
         can?(@current_user, :create_merge_request_from, @project) &&
-        ::Gitlab::UserAccess.new(@current_user, project: @project).can_push_to_branch?(source_branch)
+        ::Gitlab::UserAccess.new(@current_user, container: @project).can_push_to_branch?(source_branch)
     end
   end
 end

ee/lib/ee/gitlab/geo_git_access.rb

@@ -18,8 +18,8 @@ module EE
 
       private
 
-      def custom_action_for(cmd)
-        return unless custom_action_for?(cmd)
+      def geo_custom_action
+        return unless geo_custom_action?
 
         payload = {
           'action' => 'geo_proxy_to_primary',
@@ -32,15 +32,17 @@ module EE
         ::Gitlab::GitAccessResult::CustomAction.new(payload, messages)
       end
 
-      def custom_action_for?(cmd)
+      def geo_custom_action?
         return unless ::Gitlab::Database.read_only?
         return unless ::Gitlab::Geo.secondary_with_primary?
 
-        receive_pack?(cmd) || upload_pack_and_not_replicated?(cmd)
+        receive_pack? || upload_pack_and_not_replicated?
       end
 
-      def upload_pack_and_not_replicated?(cmd)
-        upload_pack?(cmd) && !::Geo::ProjectRegistry.repository_replicated_for?(project.id)
+      def upload_pack_and_not_replicated?
+        return false unless project
+
+        upload_pack? && !::Geo::ProjectRegistry.repository_replicated_for?(project.id)
       end
 
       def messages
@@ -90,7 +92,7 @@ module EE
       end
 
       def custom_action_api_endpoints_for(cmd)
-        receive_pack?(cmd) ? custom_action_push_api_endpoints : custom_action_pull_api_endpoints
+        receive_pack? ? custom_action_push_api_endpoints : custom_action_pull_api_endpoints
       end
 
       def custom_action_pull_api_endpoints

ee/lib/ee/gitlab/git_access.rb

@@ -23,6 +23,14 @@ module EE
         super
       end
 
+      def group?
+        container.is_a?(Group)
+      end
+
+      def group
+        container if group?
+      end
+
       protected
 
       override :user
@@ -35,11 +43,8 @@ module EE
       private
 
       override :check_custom_action
-      def check_custom_action(cmd)
-        custom_action = custom_action_for(cmd)
-        return custom_action if custom_action
-
-        super
+      def check_custom_action
+        geo_custom_action || super
       end
 
       override :check_for_console_messages

ee/lib/ee/gitlab/git_access_wiki.rb

@@ -3,12 +3,64 @@
 module EE
   module Gitlab
     module GitAccessWiki
+      extend ::Gitlab::Utils::Override
       include GeoGitAccess
 
+      ERROR_MESSAGES = {
+        write_to_group_wiki: "You are not allowed to write to this group's wiki.",
+        group_not_found: 'The group you were looking for could not be found.',
+        no_group_repo: 'A repository for this group wiki does not exist yet.'
+      }.freeze
+
+      override :project?
+      def project?
+        !group?
+      end
+
+      override :check_container!
+      def check_container!
+        return check_group! if group?
+
+        super
+      end
+
+      override :check_push_access!
+      def check_push_access!
+        return check_change_access! if group?
+
+        super
+      end
+
+      override :write_to_wiki_message
+      def write_to_wiki_message
+        return ERROR_MESSAGES[:write_to_group_wiki] if group?
+
+        super
+      end
+
+      override :no_repo_message
+      def no_repo_message
+        return ERROR_MESSAGES[:no_group_repo] if group?
+
+        super
+      end
+
       private
 
+      def check_group!
+        raise ::Gitlab::GitAccess::NotFoundError, ERROR_MESSAGES[:group_not_found] unless can_read_group?
+      end
+
+      def can_read_group?
+        if user
+          user.can?(:read_group, container)
+        else
+          Guest.can?(:read_group, container)
+        end
+      end
+
       def project_or_wiki
-        project.wiki
+        container.wiki
       end
     end
   end

ee/spec/lib/gitlab/checks/change_access_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Checks::ChangeAccess do
-  describe '#exec' do
+  describe '#validate!' do
     include_context 'push rules checks context'
 
     let(:push_rule) { create(:push_rule, deny_delete_tag: true) }
@@ -17,7 +17,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
         expect(instance).to receive(:validate!)
       end
 
-      subject.exec
+      subject.validate!
     end
   end
 end

ee/spec/lib/gitlab/git_access_spec.rb

@@ -17,6 +17,18 @@ RSpec.describe Gitlab::GitAccess do
   let(:authentication_abilities) { %i[read_project download_code push_code] }
   let(:redirected_path) { nil }
 
+  let(:access_class) do
+    Class.new(described_class) do
+      def push_ability
+        :push_code
+      end
+
+      def download_ability
+        :download_code
+      end
+    end
+  end
+
   context "when in a read-only GitLab instance" do
     before do
       create(:protected_branch, name: 'feature', project: project)
@@ -720,7 +732,7 @@ RSpec.describe Gitlab::GitAccess do
   private
 
   def access
-    described_class.new(
+    access_class.new(
       actor,
       project,
       protocol,

ee/spec/lib/gitlab/git_access_wiki_spec.rb

@@ -11,6 +11,106 @@ RSpec.describe Gitlab::GitAccessWiki do
 
   let(:access) { described_class.new(user, project, 'web', authentication_abilities: authentication_abilities, redirected_path: redirected_path) }
 
+  describe 'group wiki access' do
+    let_it_be(:group, reload: true) { create(:group, :private, :wiki_repo) }
+
+    let(:access) do
+      described_class.new(user, group, 'web',
+                          authentication_abilities: authentication_abilities,
+                          redirected_path: redirected_path)
+    end
+
+    describe '#push_access_check' do
+      subject { access.check('git-receive-pack', changes) }
+
+      context 'when user can :create_wiki' do
+        before do
+          group.add_developer(user)
+        end
+
+        it { expect { subject }.not_to raise_error }
+
+        context 'when in a read-only GitLab instance' do
+          before do
+            allow(Gitlab::Database).to receive(:read_only?) { true }
+          end
+
+          it 'does not give access to upload wiki code' do
+            expect { subject }.to raise_error(Gitlab::GitAccess::ForbiddenError, "You can't push code to a read-only GitLab instance.")
+          end
+        end
+      end
+
+      context 'when user cannot :create_wiki' do
+        before do
+          group.add_reporter(user)
+        end
+
+        specify do
+          expect { subject }.to raise_error(Gitlab::GitAccess::ForbiddenError, "You are not allowed to write to this group's wiki.")
+        end
+      end
+    end
+
+    describe '#check_download_access!' do
+      subject { access.check('git-upload-pack', Gitlab::GitAccess::ANY) }
+
+      context 'the user has at least reporter access' do
+        before do
+          group.add_reporter(user)
+        end
+
+        context 'when wiki feature is enabled' do
+          it 'gives access to download wiki code' do
+            expect { subject }.not_to raise_error
+          end
+
+          context 'when the wiki repository does not exist' do
+            let(:group) { create(:group) }
+
+            it_behaves_like 'not-found git access' do
+              let(:message) { 'A repository for this group wiki does not exist yet.' }
+            end
+          end
+        end
+
+        context 'when wiki feature is disabled' do
+          before do
+            stub_feature_flags(group_wiki: false)
+          end
+
+          it_behaves_like 'forbidden git access' do
+            let(:message) { 'You are not allowed to download files from this wiki.' }
+          end
+        end
+      end
+
+      context 'the user does not have access' do
+        it_behaves_like 'not-found git access' do
+          let(:message) { 'The group you were looking for could not be found.' }
+        end
+      end
+
+      context 'the group is public' do
+        let(:group) { create(:group, :public, :wiki_repo) }
+
+        it 'gives access to download wiki code' do
+          expect { subject }.not_to raise_error
+        end
+
+        context 'when wiki feature is disabled' do
+          before do
+            stub_feature_flags(group_wiki: false)
+          end
+
+          it_behaves_like 'forbidden git access' do
+            let(:message) { 'You are not allowed to download files from this wiki.' }
+          end
+        end
+      end
+    end
+  end
+
   context "when in a read-only GitLab instance" do
     subject { access.check('git-receive-pack', changes) }
 

ee/spec/lib/gitlab/user_access_spec.rb

@@ -6,7 +6,7 @@ RSpec.describe Gitlab::UserAccess do
   include ExternalAuthorizationServiceHelpers
 
   let(:user) { create(:user) }
-  let(:access) { described_class.new(user, project: project) }
+  let(:access) { described_class.new(user, container: project) }
 
   describe '#can_push_to_branch?' do
     describe 'push to empty project' do

lib/api/commits.rb

@@ -13,7 +13,7 @@ module API
 
     helpers do
       def user_access
-        @user_access ||= Gitlab::UserAccess.new(current_user, project: user_project)
+        @user_access ||= Gitlab::UserAccess.new(current_user, container: user_project)
       end
 
       def authorize_push_to_branch!(branch)

lib/api/entities/branch.rb

@@ -32,7 +32,7 @@ module API
       end
 
       expose :can_push do |repo_branch, options|
-        Gitlab::UserAccess.new(options[:current_user], project: options[:project]).can_push_to_branch?(repo_branch.name)
+        Gitlab::UserAccess.new(options[:current_user], container: options[:project]).can_push_to_branch?(repo_branch.name)
       end
 
       expose :default do |repo_branch, options|

lib/api/internal/base.rb

@@ -92,7 +92,7 @@ module API
 
             # If we have created a project directly from a git push
             # we have to assign its value to both @project and @container
-            @project = @container = access_checker.project
+            @project = @container = access_checker.container
           end
         end
       end

lib/api/merge_requests.rb

@@ -97,7 +97,7 @@ module API
 
         user_access = Gitlab::UserAccess.new(
           current_user,
-          project: merge_request.source_project
+          container: merge_request.source_project
         )
 
         forbidden!('Cannot push to source branch') unless

lib/gitlab/build_access.rb

@@ -2,8 +2,6 @@
 
 module Gitlab
   class BuildAccess < UserAccess
-    attr_accessor :user, :project
-
     # This bypasses the `can?(:access_git)`-check we normally do in `UserAccess`
     # for CI. That way if a user was able to trigger a pipeline, then the
     # build is allowed to clone the project.

lib/gitlab/checks/change_access.rb

@@ -25,7 +25,7 @@ module Gitlab
         @logger.append_message("Running checks for ref: #{@branch_name || @tag_name}")
       end
 
-      def exec
+      def validate!
         ref_level_checks
         # Check of commits should happen as the last step
         # given they're expensive in terms of performance

lib/gitlab/ci/pipeline/chain/validate/abilities.rb

@@ -34,7 +34,7 @@ module Gitlab
             end
 
             def allowed_to_write_ref?
-              access = Gitlab::UserAccess.new(current_user, project: project)
+              access = Gitlab::UserAccess.new(current_user, container: project)
 
               if @command.branch_exists?
                 access.can_update_branch?(@command.ref)

lib/gitlab/git_access.rb

@@ -23,7 +23,6 @@ module Gitlab
       deploy_key_upload: 'This deploy key does not have write access to this project.',
       no_repo: 'A repository for this project does not exist yet.',
       project_not_found: 'The project you were looking for could not be found.',
-      namespace_not_found: 'The namespace you were looking for could not be found.',
       command_not_allowed: "The command you're trying to execute is not allowed.",
       upload_pack_disabled_over_http: 'Pulling over HTTP is not allowed.',
       receive_pack_disabled_over_http: 'Pushing over HTTP is not allowed.',
@@ -43,38 +42,42 @@ module Gitlab
     PUSH_COMMANDS = %w{git-receive-pack}.freeze
     ALL_COMMANDS = DOWNLOAD_COMMANDS + PUSH_COMMANDS
 
-    attr_reader :actor, :project, :protocol, :authentication_abilities, :namespace_path, :repository_path, :redirected_path, :auth_result_type, :changes, :logger
+    attr_reader :actor, :protocol, :authentication_abilities,
+                :namespace_path, :redirected_path, :auth_result_type,
+                :cmd, :changes
+    attr_accessor :container
 
-    alias_method :container, :project
-
-    def initialize(actor, project, protocol, authentication_abilities:, namespace_path: nil, repository_path: nil, redirected_path: nil, auth_result_type: nil)
+    def initialize(actor, container, protocol, authentication_abilities:, namespace_path: nil, repository_path: nil, redirected_path: nil, auth_result_type: nil)
       @actor     = actor
-      @project  = project
+      @container = container
       @protocol  = protocol
       @authentication_abilities = Array(authentication_abilities)
-      @namespace_path = namespace_path || project&.namespace&.full_path
-      @repository_path = repository_path || project&.path
+      @namespace_path = namespace_path
+      @repository_path = repository_path
       @redirected_path = redirected_path
       @auth_result_type = auth_result_type
     end
 
+    def repository_path
+      @repository_path ||= project&.path
+    end
+
     def check(cmd, changes)
-      @logger = Checks::TimedLogger.new(timeout: INTERNAL_TIMEOUT, header: LOG_HEADER)
       @changes = changes
+      @cmd = cmd
 
       check_protocol!
       check_valid_actor!
       check_active_user!
-      check_authentication_abilities!(cmd)
-      check_command_disabled!(cmd)
-      check_command_existence!(cmd)
+      check_authentication_abilities!
+      check_command_disabled!
+      check_command_existence!
 
-      custom_action = check_custom_action(cmd)
+      custom_action = check_custom_action
       return custom_action if custom_action
 
-      check_db_accessibility!(cmd)
-      check_namespace!
-      check_project!(cmd)
+      check_db_accessibility!
+      check_container!
       check_repository_existence!
 
       case cmd
@@ -87,12 +90,27 @@ module Gitlab
       success_result
     end
 
+    def logger
+      @logger ||= Checks::TimedLogger.new(timeout: INTERNAL_TIMEOUT, header: LOG_HEADER)
+    end
+
     def guest_can_download_code?
-      Guest.can?(:download_code, project)
+      Guest.can?(download_ability, container)
     end
 
     def user_can_download_code?
-      authentication_abilities.include?(:download_code) && user_access.can_do_action?(:download_code)
+      authentication_abilities.include?(:download_code) &&
+        user_access.can_do_action?(download_ability)
+    end
+
+    # @return [Symbol] the name of a Declarative Policy ability to check
+    def download_ability
+      raise NotImplementedError
+    end
+
+    # @return [Symbol] the name of a Declarative Policy ability to check
+    def push_ability
+      raise NotImplementedError
     end
 
     def build_can_download_code?
@@ -111,13 +129,17 @@ module Gitlab
 
     private
 
-    def check_project!(_cmd)
+    def check_container!
+      check_project! if project?
+    end
+
+    def check_project!
       check_project_accessibility!
       add_project_moved_message!
     end
 
-    def check_custom_action(cmd)
-      nil
+    def check_custom_action
+      # no-op: Overridden in EE
     end
 
     def check_for_console_messages
@@ -152,12 +174,6 @@ module Gitlab
       end
     end
 
-    def check_namespace!
-      return if namespace_path.present?
-
-      raise NotFoundError, ERROR_MESSAGES[:namespace_not_found]
-    end
-
     def check_active_user!
       return unless user
 
@@ -167,25 +183,29 @@ module Gitlab
       end
     end
 
-    def check_authentication_abilities!(cmd)
+    def check_authentication_abilities!
       case cmd
       when *DOWNLOAD_COMMANDS
         unless authentication_abilities.include?(:download_code) || authentication_abilities.include?(:build_download_code)
-          raise ForbiddenError, ERROR_MESSAGES[:auth_download]
+          raise ForbiddenError, error_message(:auth_download)
         end
       when *PUSH_COMMANDS
         unless authentication_abilities.include?(:push_code)
-          raise ForbiddenError, ERROR_MESSAGES[:auth_upload]
+          raise ForbiddenError, error_message(:auth_upload)
         end
       end
     end
 
     def check_project_accessibility!
       if project.blank? || !can_read_project?
-        raise NotFoundError, ERROR_MESSAGES[:project_not_found]
+        raise NotFoundError, not_found_message
       end
     end
 
+    def not_found_message
+      error_message(:project_not_found)
+    end
+
     def add_project_moved_message!
       return if redirected_path.nil?
 
@@ -194,34 +214,34 @@ module Gitlab
       project_moved.add_message
     end
 
-    def check_command_disabled!(cmd)
-      if upload_pack?(cmd)
+    def check_command_disabled!
+      if upload_pack?
         check_upload_pack_disabled!
-      elsif receive_pack?(cmd)
+      elsif receive_pack?
         check_receive_pack_disabled!
       end
     end
 
     def check_upload_pack_disabled!
       if http? && upload_pack_disabled_over_http?
-        raise ForbiddenError, ERROR_MESSAGES[:upload_pack_disabled_over_http]
+        raise ForbiddenError, error_message(:upload_pack_disabled_over_http)
       end
     end
 
     def check_receive_pack_disabled!
       if http? && receive_pack_disabled_over_http?
-        raise ForbiddenError, ERROR_MESSAGES[:receive_pack_disabled_over_http]
+        raise ForbiddenError, error_message(:receive_pack_disabled_over_http)
       end
     end
 
-    def check_command_existence!(cmd)
+    def check_command_existence!
       unless ALL_COMMANDS.include?(cmd)
-        raise ForbiddenError, ERROR_MESSAGES[:command_not_allowed]
+        raise ForbiddenError, error_message(:command_not_allowed)
       end
     end
 
-    def check_db_accessibility!(cmd)
-      return unless receive_pack?(cmd)
+    def check_db_accessibility!
+      return unless receive_pack?
 
       if Gitlab::Database.read_only?
         raise ForbiddenError, push_to_read_only_message
@@ -229,9 +249,11 @@ module Gitlab
     end
 
     def check_repository_existence!
-      unless repository.exists?
-        raise NotFoundError, ERROR_MESSAGES[:no_repo]
+      raise NotFoundError, no_repo_message unless repository.exists?
     end
+
+    def no_repo_message
+      error_message(:no_repo)
     end
 
     def check_download_access!
@@ -242,44 +264,62 @@ module Gitlab
         guest_can_download_code?
 
       unless passed
-        raise ForbiddenError, ERROR_MESSAGES[:download]
+        raise ForbiddenError, download_forbidden_message
+      end
+    end
+
+    def download_forbidden_message
+      error_message(:download)
     end
+
+    # We assume that all git-access classes are in project context by default.
+    # Override this method to be more specific.
+    def project?
+      true
+    end
+
+    def project
+      container if container.is_a?(::Project)
     end
 
     def check_push_access!
-      if project.repository_read_only?
-        raise ForbiddenError, ERROR_MESSAGES[:read_only]
+      if container.repository_read_only?
+        raise ForbiddenError, error_message(:read_only)
       end
 
       if deploy_key?
         unless deploy_key.can_push_to?(project)
-          raise ForbiddenError, ERROR_MESSAGES[:deploy_key_upload]
+          raise ForbiddenError, error_message(:deploy_key_upload)
         end
       elsif user
         # User access is verified in check_change_access!
       else
-        raise ForbiddenError, ERROR_MESSAGES[:upload]
+        raise ForbiddenError, error_message(:upload)
       end
 
       check_change_access!
     end
 
+    def user_can_push?
+      user_access.can_do_action?(push_ability)
+    end
+
     def check_change_access!
       # Deploy keys with write access can push anything
       return if deploy_key?
 
       if changes == ANY
-        can_push = user_access.can_do_action?(:push_code) ||
-          project.any_branch_allows_collaboration?(user_access.user)
+        can_push = user_can_push? ||
+          project&.any_branch_allows_collaboration?(user_access.user)
 
         unless can_push
-          raise ForbiddenError, ERROR_MESSAGES[:push_code]
+          raise ForbiddenError, error_message(:push_code)
         end
       else
         # If there are worktrees with a HEAD pointing to a non-existent object,
         # calls to `git rev-list --all` will fail in git 2.15+. This should also
         # clear stale lock files.
-        project.repository.clean_stale_repository_files
+        project.repository.clean_stale_repository_files if project.present?
 
         # Iterate over all changes to find if user allowed all of them to be applied
         changes_list.each.with_index do |change, index|
@@ -293,16 +333,14 @@ module Gitlab
     end
 
     def check_single_change_access(change, skip_lfs_integrity_check: false)
-      change_access = Checks::ChangeAccess.new(
+      Checks::ChangeAccess.new(
         change,
         user_access: user_access,
         project: project,
         skip_lfs_integrity_check: skip_lfs_integrity_check,
         protocol: protocol,
         logger: logger
-      )
-
-      change_access.exec
+      ).validate!
     rescue Checks::TimedLogger::TimeoutError
       raise TimeoutError, logger.full_message
     end
@@ -347,12 +385,12 @@ module Gitlab
       protocol == 'http'
     end
 
-    def upload_pack?(command)
-      command == 'git-upload-pack'
+    def upload_pack?
+      cmd == 'git-upload-pack'
     end
 
-    def receive_pack?(command)
-      command == 'git-receive-pack'
+    def receive_pack?
+      cmd == 'git-receive-pack'
     end
 
     def upload_pack_disabled_over_http?
@@ -365,6 +403,16 @@ module Gitlab
 
     protected
 
+    def error_message(key)
+      self.class.ancestors.each do |cls|
+        return cls.const_get('ERROR_MESSAGES', false).fetch(key)
+      rescue NameError, KeyError
+        next
+      end
+
+      raise ArgumentError, "No error message defined for #{key}"
+    end
+
     def success_result
       ::Gitlab::GitAccessResult::Success.new(console_messages: check_for_console_messages)
     end
@@ -374,9 +422,7 @@ module Gitlab
     end
 
     def user
-      return @user if defined?(@user)
-
-      @user =
+      strong_memoize(:user) do
         case actor
         when User
           actor
@@ -388,19 +434,20 @@ module Gitlab
           nil
         end
       end
+    end
 
     def user_access
       @user_access ||= if ci?
                          CiAccess.new
                        elsif user && request_from_ci_build?
-                         BuildAccess.new(user, project: project)
+                         BuildAccess.new(user, container: container)
                        else
-                         UserAccess.new(user, project: project)
+                         UserAccess.new(user, container: container)
                        end
     end
 
     def push_to_read_only_message
-      ERROR_MESSAGES[:cannot_push_to_read_only]
+      error_message(:cannot_push_to_read_only)
     end
 
     def repository

lib/gitlab/git_access_design.rb

@@ -2,6 +2,8 @@
 
 module Gitlab
   class GitAccessDesign < GitAccess
+    extend ::Gitlab::Utils::Override
+
     def check(_cmd, _changes)
       check_protocol!
       check_can_create_design!
@@ -9,6 +11,11 @@ module Gitlab
       success_result
     end
 
+    override :push_ability
+    def push_ability
+      :create_design
+    end
+
     private
 
     def check_protocol!
@@ -18,7 +25,7 @@ module Gitlab
     end
 
     def check_can_create_design!
-      unless user&.can?(:create_design, project)
+      unless user_can_push?
         raise ::Gitlab::GitAccess::ForbiddenError, "You are not allowed to manage designs of this project"
       end
     end

lib/gitlab/git_access_project.rb

@@ -6,21 +6,41 @@ module Gitlab
 
     CreationError = Class.new(StandardError)
 
+    ERROR_MESSAGES = {
+      namespace_not_found: 'The namespace you were looking for could not be found.'
+    }.freeze
+
+    override :download_ability
+    def download_ability
+      :download_code
+    end
+
+    override :push_ability
+    def push_ability
+      :push_code
+    end
+
     private
 
-    override :check_project!
-    def check_project!(cmd)
-      ensure_project_on_push!(cmd)
+    override :check_container!
+    def check_container!
+      check_namespace!
+      ensure_project_on_push!
 
       super
     end
 
-    def ensure_project_on_push!(cmd)
-      return if project || deploy_key?
-      return unless receive_pack?(cmd) && changes == ANY && authentication_abilities.include?(:push_code)
+    def check_namespace!
+      raise NotFoundError, ERROR_MESSAGES[:namespace_not_found] unless namespace_path.present?
+    end
 
-      namespace = Namespace.find_by_full_path(namespace_path)
+    def namespace
+      @namespace ||= Namespace.find_by_full_path(namespace_path)
+    end
 
+    def ensure_project_on_push!
+      return if project || deploy_key?
+      return unless receive_pack? && changes == ANY && authentication_abilities.include?(:push_code)
       return unless user&.can?(:create_projects, namespace)
 
       project_params = {
@@ -35,8 +55,8 @@ module Gitlab
         raise CreationError, "Could not create project: #{project.errors.full_messages.join(', ')}"
       end
 
-      @project = project
-      user_access.project = @project
+      self.container = project
+      user_access.container = project
 
       Checks::ProjectCreated.new(repository, user, protocol).add_message
     end

lib/gitlab/git_access_snippet.rb

@@ -9,50 +9,68 @@ module Gitlab
       read_snippet: 'You are not allowed to read this snippet.',
       update_snippet: 'You are not allowed to update this snippet.',
       snippet_not_found: 'The snippet you were looking for could not be found.',
-      repository_not_found: 'The snippet repository you were looking for could not be found.'
+      no_repo: 'The snippet repository you were looking for could not be found.'
     }.freeze
 
-    attr_reader :snippet
-
-    alias_method :container, :snippet
+    alias_method :snippet, :container
 
     def initialize(actor, snippet, protocol, **kwargs)
-      @snippet = snippet
-
-      super(actor, snippet&.project, protocol, **kwargs)
+      super(actor, snippet, protocol, **kwargs)
 
       @auth_result_type = nil
       @authentication_abilities &= [:download_code, :push_code]
     end
 
+    override :check
     def check(cmd, changes)
-      # TODO: Investigate if expanding actor/authentication types are needed.
-      # https://gitlab.com/gitlab-org/gitlab/issues/202190
-      if actor && !actor.is_a?(User) && !actor.instance_of?(Key)
-        raise ForbiddenError, ERROR_MESSAGES[:authentication_mechanism]
-      end
-
       check_snippet_accessibility!
 
       super
     end
 
+    override :download_ability
+    def download_ability
+      :read_snippet
+    end
+
+    override :push_ability
+    def push_ability
+      :update_snippet
+    end
+
     private
 
-    override :check_namespace!
-    def check_namespace!
-      return unless snippet.is_a?(ProjectSnippet)
+    # TODO: Implement EE/Geo https://gitlab.com/gitlab-org/gitlab/issues/205629
+    override :check_custom_action
+    def check_custom_action
+      # snippets never return custom actions, such as geo replication.
+    end
 
-      super
+    override :project?
+    def project?
+      project_snippet?
+    end
+
+    override :project
+    def project
+      snippet&.project
     end
 
-    override :check_project!
-    def check_project!(cmd)
-      return unless snippet.is_a?(ProjectSnippet)
+    override :check_valid_actor!
+    def check_valid_actor!
+      # TODO: Investigate if expanding actor/authentication types are needed.
+      # https://gitlab.com/gitlab-org/gitlab/issues/202190
+      if actor && !actor.is_a?(User) && !actor.instance_of?(Key)
+        raise ForbiddenError, ERROR_MESSAGES[:authentication_mechanism]
+      end
 
       super
     end
 
+    def project_snippet?
+      snippet.is_a?(ProjectSnippet)
+    end
+
     override :check_push_access!
     def check_push_access!
       raise ForbiddenError, ERROR_MESSAGES[:update_snippet] unless user
@@ -82,19 +100,9 @@ module Gitlab
       end
     end
 
-    override :guest_can_download_code?
-    def guest_can_download_code?
-      Guest.can?(:read_snippet, snippet)
-    end
-
-    override :user_can_download_code?
-    def user_can_download_code?
-      authentication_abilities.include?(:download_code) && user_access.can_do_action?(:read_snippet)
-    end
-
     override :check_change_access!
     def check_change_access!
-      unless user_access.can_do_action?(:update_snippet)
+      unless user_can_push?
         raise ForbiddenError, ERROR_MESSAGES[:update_snippet]
       end
 
@@ -109,31 +117,19 @@ module Gitlab
       check_push_size!
     end
 
-    def check_single_change_access(change)
+    override :check_single_change_access
+    def check_single_change_access(change, _skip_lfs_integrity_check: false)
       Checks::SnippetCheck.new(change, logger: logger).validate!
       Checks::PushFileCountCheck.new(change, repository: repository, limit: Snippet.max_file_limit(user), logger: logger).validate!
     rescue Checks::TimedLogger::TimeoutError
       raise TimeoutError, logger.full_message
     end
 
-    override :check_repository_existence!
-    def check_repository_existence!
-      unless repository.exists?
-        raise NotFoundError, ERROR_MESSAGES[:repository_not_found]
-      end
-    end
-
     override :user_access
     def user_access
       @user_access ||= UserAccessSnippet.new(user, snippet: snippet)
     end
 
-    # TODO: Implement EE/Geo https://gitlab.com/gitlab-org/gitlab/issues/205629
-    override :check_custom_action
-    def check_custom_action(cmd)
-      nil
-    end
-
     override :check_size_limit?
     def check_size_limit?
       return false if user&.migration_bot?

lib/gitlab/git_access_wiki.rb

@@ -2,41 +2,50 @@
 
 module Gitlab
   class GitAccessWiki < GitAccess
-    prepend_if_ee('EE::Gitlab::GitAccessWiki') # rubocop: disable Cop/InjectEnterpriseEditionModule
+    extend ::Gitlab::Utils::Override
 
     ERROR_MESSAGES = {
+      download: 'You are not allowed to download files from this wiki.',
+      not_found: 'The wiki you were looking for could not be found.',
+      no_repo: 'A repository for this wiki does not exist yet.',
       read_only: "You can't push code to a read-only GitLab instance.",
       write_to_wiki: "You are not allowed to write to this project's wiki."
     }.freeze
 
-    def guest_can_download_code?
-      Guest.can?(:download_wiki_code, project)
+    override :download_ability
+    def download_ability
+      :download_wiki_code
     end
 
-    def user_can_download_code?
-      authentication_abilities.include?(:download_code) && user_access.can_do_action?(:download_wiki_code)
+    override :push_ability
+    def push_ability
+      :create_wiki
     end
 
+    override :check_change_access!
     def check_change_access!
-      unless user_access.can_do_action?(:create_wiki)
-        raise ForbiddenError, ERROR_MESSAGES[:write_to_wiki]
-      end
-
-      if Gitlab::Database.read_only?
-        raise ForbiddenError, push_to_read_only_message
-      end
+      raise ForbiddenError, write_to_wiki_message unless user_can_push?
 
       true
     end
 
     def push_to_read_only_message
-      ERROR_MESSAGES[:read_only]
+      error_message(:read_only)
     end
 
-    private
+    def write_to_wiki_message
+      error_message(:write_to_wiki)
+    end
 
+    def not_found_message
+      error_message(:not_found)
+    end
+
+    override :repository
     def repository
-      project.wiki.repository
+      container.wiki.repository
     end
   end
 end
+
+Gitlab::GitAccessWiki.prepend_if_ee('EE::Gitlab::GitAccessWiki')

lib/gitlab/gl_repository/repo_type.rb

@@ -37,19 +37,19 @@ module Gitlab
       end
 
       def wiki?
-        self == WIKI
+        name == :wiki
       end
 
       def project?
-        self == PROJECT
+        name == :project
       end
 
       def snippet?
-        self == SNIPPET
+        name == :snippet
       end
 
       def design?
-        self == DESIGN
+        name == :design
       end
 
       def path_suffix

lib/gitlab/user_access.rb

@@ -5,15 +5,16 @@ module Gitlab
     extend Gitlab::Cache::RequestCache
 
     request_cache_key do
-      [user&.id, project&.id]
+      [user&.id, container&.to_global_id]
     end
 
-    attr_reader :user
-    attr_accessor :project
+    attr_reader :user, :push_ability
+    attr_accessor :container
 
-    def initialize(user, project: nil)
+    def initialize(user, container: nil, push_ability: :push_code)
       @user = user
-      @project = project
+      @container = container
+      @push_ability = push_ability
     end
 
     def can_do_action?(action)
@@ -21,7 +22,7 @@ module Gitlab
 
       permission_cache[action] =
         permission_cache.fetch(action) do
-          user.can?(action, project)
+          user.can?(action, container)
         end
     end
 
@@ -42,20 +43,20 @@ module Gitlab
     request_cache def can_create_tag?(ref)
       return false unless can_access_git?
 
-      if protected?(ProtectedTag, project, ref)
+      if protected?(ProtectedTag, ref)
         protected_tag_accessible_to?(ref, action: :create)
       else
-        user.can?(:admin_tag, project)
+        user.can?(:admin_tag, container)
       end
     end
 
     request_cache def can_delete_branch?(ref)
       return false unless can_access_git?
 
-      if protected?(ProtectedBranch, project, ref)
-        user.can?(:push_to_delete_protected_branch, project)
+      if protected?(ProtectedBranch, ref)
+        user.can?(:push_to_delete_protected_branch, container)
       else
-        user.can?(:push_code, project)
+        can_push?
       end
     end
 
@@ -64,36 +65,36 @@ module Gitlab
     end
 
     request_cache def can_push_to_branch?(ref)
-      return false unless can_access_git?
-      return false unless project
-
-      # Checking for an internal project to prevent an infinite loop:
-      # https://gitlab.com/gitlab-org/gitlab/issues/36805
-      if project.internal?
-        return false unless user.can?(:push_code, project)
-      else
-        return false if !user.can?(:push_code, project) && !project.branch_allows_collaboration?(user, ref)
-      end
+      return false unless can_access_git? && container && can_collaborate?(ref)
+      return true unless protected?(ProtectedBranch, ref)
 
-      if protected?(ProtectedBranch, project, ref)
       protected_branch_accessible_to?(ref, action: :push)
-      else
-        true
-      end
     end
 
     request_cache def can_merge_to_branch?(ref)
       return false unless can_access_git?
 
-      if protected?(ProtectedBranch, project, ref)
+      if protected?(ProtectedBranch, ref)
         protected_branch_accessible_to?(ref, action: :merge)
       else
-        user.can?(:push_code, project)
+        can_push?
       end
     end
 
     private
 
+    def can_push?
+      user.can?(push_ability, container)
+    end
+
+    def can_collaborate?(ref)
+      assert_project!
+
+      # Checking for an internal project or group to prevent an infinite loop:
+      # https://gitlab.com/gitlab-org/gitlab/issues/36805
+      can_push? || (!project.internal? && project.branch_allows_collaboration?(user, ref))
+    end
+
     def permission_cache
       @permission_cache ||= {}
     end
@@ -103,6 +104,8 @@ module Gitlab
     end
 
     def protected_branch_accessible_to?(ref, action:)
+      assert_project!
+
       ProtectedBranch.protected_ref_accessible_to?(
         ref, user,
         project: project,
@@ -111,6 +114,8 @@ module Gitlab
     end
 
     def protected_tag_accessible_to?(ref, action:)
+      assert_project!
+
       ProtectedTag.protected_ref_accessible_to?(
         ref, user,
         project: project,
@@ -118,8 +123,22 @@ module Gitlab
         protected_refs: project.protected_tags)
     end
 
-    request_cache def protected?(kind, project, refs)
+    request_cache def protected?(kind, refs)
+      assert_project!
+
       kind.protected?(project, refs)
     end
+
+    def project
+      container
+    end
+
+    # Any method that assumes that it is operating on a project should make this
+    # explicit by calling `#assert_project!`.
+    # TODO: remove when we make this class polymorphic enough not to care about projects
+    # See: https://gitlab.com/gitlab-org/gitlab/-/issues/227635
+    def assert_project!
+      raise "No project! #{project.inspect} is not a Project" unless project.is_a?(::Project)
+    end
   end
 end

lib/gitlab/user_access_snippet.rb

@@ -2,6 +2,7 @@
 
 module Gitlab
   class UserAccessSnippet < UserAccess
+    extend ::Gitlab::Utils::Override
     extend ::Gitlab::Cache::RequestCache
     # TODO: apply override check https://gitlab.com/gitlab-org/gitlab/issues/205677
 
@@ -9,11 +10,10 @@ module Gitlab
       [user&.id, snippet&.id]
     end
 
-    attr_reader :snippet
+    alias_method :snippet, :container
 
     def initialize(user, snippet: nil)
-      @user = user
-      @snippet = snippet
+      super(user, container: snippet)
       @project = snippet&.project
     end
 
@@ -43,13 +43,9 @@ module Gitlab
 
     def can_push_to_branch?(ref)
       return true if snippet_migration?
-
-      super
-
       return false unless snippet
-      return false unless can_do_action?(:update_snippet)
 
-      true
+      can_do_action?(:update_snippet)
     end
 
     def can_merge_to_branch?(ref)
@@ -59,5 +55,8 @@ module Gitlab
     def snippet_migration?
       user&.migration_bot? && snippet
     end
+
+    override :project
+    attr_reader :project
   end
 end

lib/gitlab/view/presenter/base.rb

@@ -30,6 +30,10 @@ module Gitlab
           Gitlab::UrlBuilder.instance
         end
 
+        def is_a?(type)
+          super || subject.is_a?(type)
+        end
+
         class_methods do
           def presenter?
             true

spec/controllers/concerns/checks_collaboration_spec.rb

@@ -33,7 +33,7 @@ RSpec.describe ChecksCollaboration do
     it 'is true when the user can push to a branch of the project' do
       fake_access = double('Gitlab::UserAccess')
       expect(fake_access).to receive(:can_push_to_branch?).with('a-branch').and_return(true)
-      expect(Gitlab::UserAccess).to receive(:new).with(user, project: project).and_return(fake_access)
+      expect(Gitlab::UserAccess).to receive(:new).with(user, container: project).and_return(fake_access)
 
       expect(helper.can_collaborate_with_project?(project, ref: 'a-branch')).to be_truthy
     end

spec/lib/gitlab/build_access_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe Gitlab::BuildAccess do
   let(:project) { create(:project) }
 
   describe '#can_do_action' do
-    subject { described_class.new(user, project: project).can_do_action?(:download_code) }
+    subject { described_class.new(user, container: project).can_do_action?(:download_code) }
 
     context 'when the user can do an action on the project but cannot access git' do
       before do

spec/lib/gitlab/checks/change_access_spec.rb

@@ -3,14 +3,14 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Checks::ChangeAccess do
-  describe '#exec' do
+  describe '#validate!' do
     include_context 'change access checks context'
 
     subject { change_access }
 
     context 'without failed checks' do
       it "doesn't raise an error" do
-        expect { subject.exec }.not_to raise_error
+        expect { subject.validate! }.not_to raise_error
       end
 
       it 'calls pushes checks' do
@@ -18,7 +18,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
           expect(instance).to receive(:validate!)
         end
 
-        subject.exec
+        subject.validate!
       end
 
       it 'calls branches checks' do
@@ -26,7 +26,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
           expect(instance).to receive(:validate!)
         end
 
-        subject.exec
+        subject.validate!
       end
 
       it 'calls tags checks' do
@@ -34,7 +34,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
           expect(instance).to receive(:validate!)
         end
 
-        subject.exec
+        subject.validate!
       end
 
       it 'calls lfs checks' do
@@ -42,7 +42,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
           expect(instance).to receive(:validate!)
         end
 
-        subject.exec
+        subject.validate!
       end
 
       it 'calls diff checks' do
@@ -50,7 +50,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
           expect(instance).to receive(:validate!)
         end
 
-        subject.exec
+        subject.validate!
       end
     end
 
@@ -63,7 +63,7 @@ RSpec.describe Gitlab::Checks::ChangeAccess do
                                      protocol: protocol,
                                      logger: logger)
 
-        expect { access.exec }.to raise_error(Gitlab::Checks::TimedLogger::TimeoutError)
+        expect { access.validate! }.to raise_error(Gitlab::Checks::TimedLogger::TimeoutError)
       end
     end
   end

spec/lib/gitlab/git_access_project_spec.rb

@@ -5,6 +5,7 @@ require 'spec_helper'
 RSpec.describe Gitlab::GitAccessProject do
   let_it_be(:user) { create(:user) }
   let_it_be(:project) { create(:project, :repository) }
+  let(:container) { project }
   let(:actor) { user }
   let(:project_path) { project.path }
   let(:namespace_path) { project&.namespace&.path }
@@ -13,19 +14,32 @@ RSpec.describe Gitlab::GitAccessProject do
   let(:changes) { Gitlab::GitAccess::ANY }
   let(:push_access_check) { access.check('git-receive-pack', changes) }
   let(:pull_access_check) { access.check('git-upload-pack', changes) }
+  let(:access) do
+    described_class.new(actor, container, protocol,
+                        authentication_abilities: authentication_abilities,
+                        repository_path: project_path, namespace_path: namespace_path)
+  end
+
+  describe '#check_namespace!' do
+    context 'when namespace is nil' do
+      let(:namespace_path) { nil }
+
+      it 'does not allow push and pull access' do
+        aggregate_failures do
+          expect { push_access_check }.to raise_namespace_not_found
+          expect { pull_access_check }.to raise_namespace_not_found
+        end
+      end
+    end
+  end
 
   describe '#check_project_accessibility!' do
     context 'when the project is nil' do
-      let(:project) { nil }
+      let(:container) { nil }
       let(:project_path) { "new-project" }
 
       context 'when user is allowed to create project in namespace' do
         let(:namespace_path) { user.namespace.path }
-        let(:access) do
-          described_class.new(actor, nil,
-            protocol, authentication_abilities: authentication_abilities,
-            repository_path: project_path, namespace_path: namespace_path)
-        end
 
         it 'blocks pull access with "not found"' do
           expect { pull_access_check }.to raise_not_found
@@ -39,11 +53,6 @@ RSpec.describe Gitlab::GitAccessProject do
       context 'when user is not allowed to create project in namespace' do
         let(:user2) { create(:user) }
         let(:namespace_path) { user2.namespace.path }
-        let(:access) do
-          described_class.new(actor, nil,
-            protocol, authentication_abilities: authentication_abilities,
-            repository_path: project_path, namespace_path: namespace_path)
-        end
 
         it 'blocks push and pull with "not found"' do
           aggregate_failures do
@@ -56,22 +65,27 @@ RSpec.describe Gitlab::GitAccessProject do
   end
 
   describe '#ensure_project_on_push!' do
-    let(:access) do
-      described_class.new(actor, project,
-        protocol, authentication_abilities: authentication_abilities,
-        repository_path: project_path, namespace_path: namespace_path)
-    end
-
     before do
       allow(access).to receive(:changes).and_return(changes)
     end
 
+    shared_examples 'no project is created' do
+      let(:raise_specific_error) { raise_not_found }
+      let(:action) { push_access_check }
+
+      it 'does not create a new project' do
+        expect { action }
+          .to raise_specific_error
+          .and change { Project.count }.by(0)
+      end
+    end
+
     context 'when push' do
       let(:cmd) { 'git-receive-pack' }
 
       context 'when project does not exist' do
         let(:project_path) { "nonexistent" }
-        let(:project) { nil }
+        let(:container) { nil }
 
         context 'when changes is _any' do
           let(:changes) { Gitlab::GitAccess::ANY }
@@ -82,8 +96,8 @@ RSpec.describe Gitlab::GitAccessProject do
             context 'when user can create project in namespace' do
               let(:namespace_path) { user.namespace.path }
 
-              it 'creates a new project' do
-                expect { access.send(:ensure_project_on_push!, cmd) }
+              it 'creates a new project in the correct namespace' do
+                expect { push_access_check }
                   .to change { Project.count }.by(1)
                   .and change { Project.where(namespace: user.namespace, name: project_path).count }.by(1)
               end
@@ -93,9 +107,7 @@ RSpec.describe Gitlab::GitAccessProject do
               let(:user2) { create(:user) }
               let(:namespace_path) { user2.namespace.path }
 
-              it 'does not create a new project' do
-                expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
-              end
+              it_behaves_like 'no project is created'
             end
           end
 
@@ -105,8 +117,8 @@ RSpec.describe Gitlab::GitAccessProject do
             context 'when user can create project in namespace' do
               let(:namespace_path) { user.namespace.path }
 
-              it 'does not create a new project' do
-                expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
+              it_behaves_like 'no project is created' do
+                let(:raise_specific_error) { raise_forbidden }
               end
             end
           end
@@ -115,32 +127,26 @@ RSpec.describe Gitlab::GitAccessProject do
         context 'when check contains actual changes' do
           let(:changes) { "#{Gitlab::Git::BLANK_SHA} 570e7b2abdd848b95f2f578043fc23bd6f6fd24d refs/heads/new_branch" }
 
-          it 'does not create a new project' do
-            expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
-          end
+          it_behaves_like 'no project is created'
         end
       end
 
       context 'when project exists' do
         let(:changes) { Gitlab::GitAccess::ANY }
-        let!(:project) { create(:project) }
+        let!(:container) { project }
 
-        it 'does not create a new project' do
-          expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
-        end
+        it_behaves_like 'no project is created'
       end
 
       context 'when deploy key is used' do
         let(:key) { create(:deploy_key, user: user) }
         let(:actor) { key }
         let(:project_path) { "nonexistent" }
-        let(:project) { nil }
+        let(:container) { nil }
         let(:namespace_path) { user.namespace.path }
         let(:changes) { Gitlab::GitAccess::ANY }
 
-        it 'does not create a new project' do
-          expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
-        end
+        it_behaves_like 'no project is created'
       end
     end
 
@@ -151,10 +157,10 @@ RSpec.describe Gitlab::GitAccessProject do
       context 'when project does not exist' do
         let(:project_path) { "new-project" }
         let(:namespace_path) { user.namespace.path }
-        let(:project) { nil }
+        let(:container) { nil }
 
-        it 'does not create a new project' do
-          expect { access.send(:ensure_project_on_push!, cmd) }.not_to change { Project.count }
+        it_behaves_like 'no project is created' do
+          let(:action)  { pull_access_check }
         end
       end
     end
@@ -163,4 +169,12 @@ RSpec.describe Gitlab::GitAccessProject do
   def raise_not_found
     raise_error(Gitlab::GitAccess::NotFoundError, Gitlab::GitAccess::ERROR_MESSAGES[:project_not_found])
   end
+
+  def raise_forbidden
+    raise_error(Gitlab::GitAccess::ForbiddenError)
+  end
+
+  def raise_namespace_not_found
+    raise_error(Gitlab::GitAccess::NotFoundError, described_class::ERROR_MESSAGES[:namespace_not_found])
+  end
 end

spec/lib/gitlab/git_access_spec.rb

@@ -20,6 +20,18 @@ RSpec.describe Gitlab::GitAccess do
   let(:push_access_check) { access.check('git-receive-pack', changes) }
   let(:pull_access_check) { access.check('git-upload-pack', changes) }
 
+  let(:access_class) do
+    Class.new(described_class) do
+      def push_ability
+        :push_code
+      end
+
+      def download_ability
+        :download_code
+      end
+    end
+  end
+
   describe '#check with single protocols allowed' do
     def disable_protocol(protocol)
       allow(Gitlab::ProtocolAccess).to receive(:allowed?).with(protocol).and_return(false)
@@ -58,7 +70,7 @@ RSpec.describe Gitlab::GitAccess do
 
         it "doesn't block http pull" do
           aggregate_failures do
-            expect { pull_access_check }.not_to raise_forbidden('Git access over HTTP is not allowed')
+            expect { pull_access_check }.not_to raise_error
           end
         end
 
@@ -67,37 +79,10 @@ RSpec.describe Gitlab::GitAccess do
 
           it "doesn't block http pull" do
             aggregate_failures do
-              expect { pull_access_check }.not_to raise_forbidden('Git access over HTTP is not allowed')
-            end
-          end
-        end
-      end
-    end
-  end
-
-  describe '#check_namespace!' do
-    context 'when namespace exists' do
-      before do
-        project.add_maintainer(user)
-      end
-
-      it 'allows push and pull access' do
-        aggregate_failures do
-          expect { push_access_check }.not_to raise_error
               expect { pull_access_check }.not_to raise_error
             end
           end
         end
-
-    context 'when namespace and project are nil' do
-      let(:project) { nil }
-      let(:namespace_path) { nil }
-
-      it 'does not allow push and pull access' do
-        aggregate_failures do
-          expect { push_access_check }.to raise_namespace_not_found
-          expect { pull_access_check }.to raise_namespace_not_found
-        end
       end
     end
   end
@@ -464,7 +449,7 @@ RSpec.describe Gitlab::GitAccess do
         let(:public_project) { create(:project, :public, :repository) }
         let(:project_path) { public_project.path }
         let(:namespace_path) { public_project.namespace.path }
-        let(:access) { described_class.new(nil, public_project, 'web', authentication_abilities: [:download_code], repository_path: project_path, namespace_path: namespace_path) }
+        let(:access) { access_class.new(nil, public_project, 'web', authentication_abilities: [:download_code], repository_path: project_path, namespace_path: namespace_path) }
 
         context 'when repository is enabled' do
           it 'give access to download code' do
@@ -859,7 +844,7 @@ RSpec.describe Gitlab::GitAccess do
         message = "Push operation timed out\n\nTiming information for debugging purposes:\nRunning checks for ref: wow"
 
         expect_next_instance_of(Gitlab::Checks::ChangeAccess) do |check|
-          expect(check).to receive(:exec).and_raise(Gitlab::Checks::TimedLogger::TimeoutError)
+          expect(check).to receive(:validate!).and_raise(Gitlab::Checks::TimedLogger::TimeoutError)
         end
 
         expect { access.check('git-receive-pack', changes) }.to raise_error(described_class::TimeoutError, message)
@@ -1067,7 +1052,7 @@ RSpec.describe Gitlab::GitAccess do
   private
 
   def access
-    described_class.new(actor, project, protocol,
+    access_class.new(actor, project, protocol,
                         authentication_abilities: authentication_abilities,
                         namespace_path: namespace_path, repository_path: project_path,
                         redirected_path: redirected_path, auth_result_type: auth_result_type)
@@ -1078,15 +1063,11 @@ RSpec.describe Gitlab::GitAccess do
   end
 
   def raise_forbidden(message)
-    raise_error(Gitlab::GitAccess::ForbiddenError, message)
+    raise_error(described_class::ForbiddenError, message)
   end
 
   def raise_not_found
-    raise_error(Gitlab::GitAccess::NotFoundError, Gitlab::GitAccess::ERROR_MESSAGES[:project_not_found])
-  end
-
-  def raise_namespace_not_found
-    raise_error(Gitlab::GitAccess::NotFoundError, Gitlab::GitAccess::ERROR_MESSAGES[:namespace_not_found])
+    raise_error(described_class::NotFoundError, described_class::ERROR_MESSAGES[:project_not_found])
   end
 
   def build_authentication_abilities

spec/lib/gitlab/git_access_wiki_spec.rb

@@ -4,8 +4,8 @@ require 'spec_helper'
 
 RSpec.describe Gitlab::GitAccessWiki do
   let(:access) { described_class.new(user, project, 'web', authentication_abilities: authentication_abilities, redirected_path: redirected_path) }
-  let(:project) { create(:project, :wiki_repo) }
-  let(:user) { create(:user) }
+  let_it_be(:project) { create(:project, :wiki_repo) }
+  let_it_be(:user) { create(:user) }
   let(:changes) { ['6f6d7e7ed 570e7b2ab refs/heads/master'] }
   let(:redirected_path) { nil }
   let(:authentication_abilities) do
@@ -17,56 +17,65 @@ RSpec.describe Gitlab::GitAccessWiki do
   end
 
   describe '#push_access_check' do
+    subject { access.check('git-receive-pack', changes) }
+
     context 'when user can :create_wiki' do
       before do
-        create(:protected_branch, name: 'master', project: project)
         project.add_developer(user)
       end
 
-      subject { access.check('git-receive-pack', changes) }
-
       it { expect { subject }.not_to raise_error }
 
       context 'when in a read-only GitLab instance' do
+        let(:message) { "You can't push code to a read-only GitLab instance." }
+
         before do
           allow(Gitlab::Database).to receive(:read_only?) { true }
         end
 
-        it 'does not give access to upload wiki code' do
-          expect { subject }.to raise_error(Gitlab::GitAccess::ForbiddenError, "You can't push code to a read-only GitLab instance.")
+        it_behaves_like 'forbidden git access'
       end
     end
+
+    context 'the user cannot :create_wiki' do
+      it_behaves_like 'not-found git access' do
+        let(:message) { 'The wiki you were looking for could not be found.' }
+      end
     end
   end
 
-  describe '#access_check_download!' do
+  describe '#check_download_access!' do
     subject { access.check('git-upload-pack', Gitlab::GitAccess::ANY) }
 
+    context 'the user can :download_wiki_code' do
       before do
         project.add_developer(user)
       end
 
-    context 'when wiki feature is enabled' do
-      it 'give access to download wiki code' do
-        expect { subject }.not_to raise_error
+      context 'when wiki feature is disabled' do
+        before do
+          project.project_feature.update_attribute(:wiki_access_level, ProjectFeature::DISABLED)
         end
 
-      context 'when the wiki repository does not exist' do
-        let(:project) { create(:project) }
+        it_behaves_like 'forbidden git access' do
+          let(:message) { include('wiki') }
+        end
+      end
 
-        it 'returns not found' do
-          expect(project.wiki_repository_exists?).to eq(false)
+      context 'when the repository does not exist' do
+        before do
+          allow(project.wiki).to receive(:repository).and_return(double('Repository', exists?: false))
+        end
 
-          expect { subject }.to raise_error(Gitlab::GitAccess::NotFoundError, 'A repository for this project does not exist yet.')
+        it_behaves_like 'not-found git access' do
+          let(:message) { include('for this wiki') }
         end
       end
     end
 
-    context 'when wiki feature is disabled' do
-      it 'does not give access to download wiki code' do
-        project.project_feature.update_attribute(:wiki_access_level, ProjectFeature::DISABLED)
-
-        expect { subject }.to raise_error(Gitlab::GitAccess::ForbiddenError, 'You are not allowed to download code from this project.')
+    context 'the user cannot :download_wiki_code' do
+      it_behaves_like 'not-found git access' do
+        let(:message) { include('wiki') }
       end
     end
   end

spec/lib/gitlab/user_access_spec.rb

@@ -5,7 +5,7 @@ require 'spec_helper'
 RSpec.describe Gitlab::UserAccess do
   include ProjectForksHelper
 
-  let(:access) { described_class.new(user, project: project) }
+  let(:access) { described_class.new(user, container: project) }
   let(:project) { create(:project, :repository) }
   let(:user) { create(:user) }
 
@@ -43,7 +43,7 @@ RSpec.describe Gitlab::UserAccess do
 
     describe 'push to empty project' do
       let(:empty_project) { create(:project_empty_repo) }
-      let(:project_access) { described_class.new(user, project: empty_project) }
+      let(:project_access) { described_class.new(user, container: empty_project) }
 
       it 'returns true for admins' do
         user.update!(admin: true)

spec/presenters/project_presenter_spec.rb

@@ -525,7 +525,7 @@ RSpec.describe ProjectPresenter do
   end
 
   describe '#statistics_buttons' do
-    let(:project) { build(:project) }
+    let(:project) { build_stubbed(:project) }
 
     it 'orders the items correctly' do
       allow(project.repository).to receive(:readme).and_return(double(name: 'readme'))

spec/requests/git_http_spec.rb

@@ -301,14 +301,14 @@ RSpec.describe 'Git HTTP requests' do
             it 'rejects clones with 404 Not Found' do
               download(path, user: user.username, password: user.password) do |response|
                 expect(response).to have_gitlab_http_status(:not_found)
-                expect(response.body).to eq(git_access_error(:project_not_found))
+                expect(response.body).to eq(git_access_wiki_error(:not_found))
               end
             end
 
             it 'rejects pushes with 404 Not Found' do
               upload(path, user: user.username, password: user.password) do |response|
                 expect(response).to have_gitlab_http_status(:not_found)
-                expect(response.body).to eq(git_access_error(:project_not_found))
+                expect(response.body).to eq(git_access_wiki_error(:not_found))
               end
             end
           end

spec/support/shared_contexts/change_access_checks_shared_context.rb

@@ -3,7 +3,7 @@
 RSpec.shared_context 'change access checks context' do
   let(:user) { create(:user) }
   let(:project) { create(:project, :repository) }
-  let(:user_access) { Gitlab::UserAccess.new(user, project: project) }
+  let(:user_access) { Gitlab::UserAccess.new(user, container: project) }
   let(:oldrev) { 'be93687618e4b132087f430a4d8fc3a609c9b77c' }
   let(:newrev) { '54fcc214b94e78d7a41a9a8fe6d87a5e59500e51' }
   let(:ref) { 'refs/heads/master' }

spec/support/shared_contexts/lib/gitlab/git_access_shared_examples.rb

+# frozen_string_literal: true
+
+RSpec.shared_examples 'forbidden git access' do
+  let(:message) { /You can't/ }
+
+  it 'prevents access' do
+    expect { subject }.to raise_error(Gitlab::GitAccess::ForbiddenError, message)
+  end
+end
+
+RSpec.shared_examples 'not-found git access' do
+  let(:message) { /not found/ }
+
+  it 'prevents access' do
+    expect { subject }.to raise_error(Gitlab::GitAccess::NotFoundError, message)
+  end
+end