Revert "Revert CODEOWNERS validation of Web requests in diff check"

This reverts commit d193b526.

changelogs/unreleased/sh-revert-codeowners-check.yml

----
-title: Revert CODEOWNERS validation of Web requests in diff check
-merge_request: 30936
-author:
-type: fixed

ee/lib/ee/gitlab/checks/diff_check.rb

@@ -12,7 +12,7 @@ module EE
         def path_validations
           validations = [super].flatten
 
-          if !updated_from_web? && project.branch_requires_code_owner_approval?(branch_name)
+          if project.branch_requires_code_owner_approval?(branch_name)
             validations << validate_code_owners
           end
 
@@ -34,11 +34,13 @@ module EE
           matched_rules = loader.entries.collect { |e| "- #{e.pattern}" }
           code_owner_path = project.repository.code_owners_blob(ref: branch_name).path || "CODEOWNERS"
 
-          "Pushes to protected branches that contain changes to files that\n" \
+          msg = "Pushes to protected branches that contain changes to files that\n" \
             "match patterns defined in `#{code_owner_path}` are disabled for\n" \
             "this project. Please submit these changes via a merge request.\n\n" \
             "The following pattern(s) from `#{code_owner_path}` were matched:\n" \
             "#{matched_rules.join('\n')}\n"
+
+          updated_from_web? ? msg.tr("\n", " ") : msg
         end
 
         def validate_path_locks?

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

@@ -88,6 +88,32 @@ describe Gitlab::Checks::DiffCheck do
           end
         end
 
+        context "and the user is not listed as a code owner" do
+          before do
+            stub_feature_flags(sectional_codeowners: false)
+          end
+
+          context "for a non-web-based request" do
+            it_behaves_like "returns an error message"
+
+            it "returns an error message with newline chars" do
+              expect(validation_result).to include("\n")
+            end
+          end
+
+          context "for a web-based request" do
+            before do
+              expect(subject).to receive(:updated_from_web?).and_return(true)
+            end
+
+            it_behaves_like "returns an error message"
+
+            it "returns an error message with newline chars removed" do
+              expect(validation_result).not_to include("\n")
+            end
+          end
+        end
+
         context "and the user is not listed as a code owner" do
           it_behaves_like "returns an error message"
         end
@@ -152,9 +178,7 @@ describe Gitlab::Checks::DiffCheck do
       end
 
       context "when the feature is enabled on the project" do
-        context "updated_from_web? == false" do
         before do
-            expect(subject).to receive(:updated_from_web?).and_return(false)
           expect(project).to receive(:branch_requires_code_owner_approval?)
             .once.and_return(true)
         end
@@ -166,18 +190,6 @@ describe Gitlab::Checks::DiffCheck do
           expect(validations.any? { |v| !v.is_a? Proc }).to be_falsy
         end
       end
-
-        context "updated_from_web? == true" do
-          before do
-            expect(subject).to receive(:updated_from_web?).and_return(true)
-            expect(project).not_to receive(:branch_requires_code_owner_approval?)
-          end
-
-          it "returns an empty array" do
-            expect(subject.send(:path_validations)).to eq([])
-          end
-        end
-      end
     end
 
     context 'file name rules' do