API: Do not mangle dots in path of project

when specifying only name during project
creation

app/services/projects/create_service.rb

@@ -210,16 +210,22 @@ module Projects
     end
 
     def set_project_name_from_path
-      # Set project name from path
-      if @project.name.present? && @project.path.present?
-        # if both name and path set - everything is ok
-      elsif @project.path.present?
+      # if both name and path set - everything is ok
+      return if @project.name.present? && @project.path.present?
+
+      if @project.path.present?
         # Set project name from path
         @project.name = @project.path.dup
       elsif @project.name.present?
         # For compatibility - set path from name
-        # TODO: remove this in 8.0
-        @project.path = @project.name.dup.parameterize
+        @project.path = @project.name.dup
+
+        # TODO: Retained for backwards compatibility. Remove in API v5.
+        #       When removed, validation errors will get bubbled up automatically.
+        #       See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52725
+        unless @project.path.match?(Gitlab::PathRegex.project_path_format_regex)
+          @project.path = @project.path.parameterize
+        end
       end
     end
 

changelogs/unreleased/18292-project-name-to-path-conversion-in-api-mangles-dots.yml

+---
+title: "API: do not mangle dots when creating project with a name"
+merge_request: 52725
+author:
+type: fixed

spec/services/projects/create_service_spec.rb

@@ -40,6 +40,48 @@ RSpec.describe Projects::CreateService, '#execute' do
     end
   end
 
+  describe 'setting name and path' do
+    subject(:project) { create_project(user, opts) }
+
+    context 'when both are set' do
+      let(:opts) { { name: 'one', path: 'two' } }
+
+      it 'keeps them as specified' do
+        expect(project.name).to eq('one')
+        expect(project.path).to eq('two')
+      end
+    end
+
+    context 'when path is set' do
+      let(:opts) { { name: 'one.two_three-four' } }
+
+      it 'sets name == path' do
+        expect(project.name).to eq('one.two_three-four')
+        expect(project.path).to eq(project.name)
+      end
+    end
+
+    context 'when name is a valid path' do
+      let(:opts) { { name: 'one.two_three-four' } }
+
+      it 'sets path == name' do
+        expect(project.name).to eq('one.two_three-four')
+        expect(project.path).to eq(project.name)
+      end
+    end
+
+    context 'when name is not a valid path' do
+      let(:opts) { { name: 'one.two_three-four and five' } }
+
+      # TODO: Retained for backwards compatibility. Remove in API v5.
+      #       See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52725
+      it 'parameterizes the name' do
+        expect(project.name).to eq('one.two_three-four and five')
+        expect(project.path).to eq('one-two_three-four-and-five')
+      end
+    end
+  end
+
   context 'user namespace' do
     it do
       project = create_project(user, opts)
@@ -419,7 +461,7 @@ RSpec.describe Projects::CreateService, '#execute' do
     context 'when another repository already exists on disk' do
       let(:opts) do
         {
-          name: 'Existing',
+          name: 'existing',
           namespace_id: user.namespace.id
         }
       end