Show a more helpful error for import status

Importing a project from GitHub for a project namespace that already exists
would show an unhelpful error, "An error occurred while importing project."
We now add the base message from Projects::CreateService when this fails.

Closes #47365

app/assets/javascripts/importer_status.js

@@ -67,7 +67,15 @@ class ImporterStatus {
         false,
       ));
     })
-    .catch(() => flash(__('An error occurred while importing project')));
+    .catch((error) => {
+      let details = error;
+
+      if (error.response && error.response.data && error.response.data.errors) {
+        details = error.response.data.errors;
+      }
+
+      flash(__(`An error occurred while importing project: ${details}`));
+    });
   }
 
   autoUpdate() {

app/controllers/import/base_controller.rb

@@ -25,4 +25,13 @@ class Import::BaseController < ApplicationController
 
     current_user.namespace
   end
+
+  def project_save_error(project)
+    # Projects::CreateService will set base message if unable to save
+    if project.errors[:base].present?
+      project.errors[:base].last
+    else
+      project.errors.full_messages.join(', ')
+    end
+  end
 end

app/controllers/import/bitbucket_controller.rb

@@ -55,7 +55,7 @@ class Import::BitbucketController < Import::BaseController
       if project.persisted?
         render json: ProjectSerializer.new.represent(project)
       else
-        render json: { errors: project.errors.full_messages }, status: :unprocessable_entity
+        render json: { errors: project_save_error(project) }, status: :unprocessable_entity
       end
     else
       render json: { errors: 'This namespace has already been taken! Please choose another one.' }, status: :unprocessable_entity

app/controllers/import/fogbugz_controller.rb

@@ -66,7 +66,7 @@ class Import::FogbugzController < Import::BaseController
     if project.persisted?
       render json: ProjectSerializer.new.represent(project)
     else
-      render json: { errors: project.errors.full_messages }, status: :unprocessable_entity
+      render json: { errors: project_save_error(project) }, status: :unprocessable_entity
     end
   end
 

app/controllers/import/github_controller.rb

@@ -48,7 +48,7 @@ class Import::GithubController < Import::BaseController
       if project.persisted?
         render json: ProjectSerializer.new.represent(project)
       else
-        render json: { errors: project.errors.full_messages }, status: :unprocessable_entity
+        render json: { errors: project_save_error(project) }, status: :unprocessable_entity
       end
     else
       render json: { errors: 'This namespace has already been taken! Please choose another one.' }, status: :unprocessable_entity

app/controllers/import/gitlab_controller.rb

@@ -32,7 +32,7 @@ class Import::GitlabController < Import::BaseController
       if project.persisted?
         render json: ProjectSerializer.new.represent(project)
       else
-        render json: { errors: project.errors.full_messages }, status: :unprocessable_entity
+        render json: { errors: project_save_error(project) }, status: :unprocessable_entity
       end
     else
       render json: { errors: 'This namespace has already been taken! Please choose another one.' }, status: :unprocessable_entity

app/controllers/import/google_code_controller.rb

@@ -92,7 +92,7 @@ class Import::GoogleCodeController < Import::BaseController
     if project.persisted?
       render json: ProjectSerializer.new.represent(project)
     else
-      render json: { errors: project.errors.full_messages }, status: :unprocessable_entity
+      render json: { errors: project_save_error(project) }, status: :unprocessable_entity
     end
   end
 

changelogs/unreleased/sh-improve-import-status-error.yml

@@ -0,0 +1,5 @@
+---
+title: Show a more helpful error for import status
+merge_request:
+author:
+type: other

spec/javascripts/importer_status_spec.js

@@ -50,6 +50,24 @@ describe('Importer Status', () => {
       })
       .catch(done.fail);
     });
+
+    it('shows error message after failed POST request', (done) => {
+      appendSetFixtures('<div class="flash-container"></div>');
+
+      mock.onPost(importUrl).reply(422, {
+        errors: 'You forgot your lunch',
+      });
+
+      instance.addToImport({
+        currentTarget: document.querySelector('.js-add-to-import'),
+      })
+      .then(() => {
+        const flashMessage = document.querySelector('.flash-text');
+        expect(flashMessage.textContent.trim()).toEqual('An error occurred while importing project: You forgot your lunch');
+        done();
+      })
+      .catch(done.fail);
+    });
   });
 
   describe('autoUpdate', () => {

spec/support/controllers/githubish_import_controller_shared_examples.rb

@@ -118,14 +118,34 @@ shared_examples 'a GitHub-ish import controller: POST create' do
     expect(response).to have_gitlab_http_status(200)
   end
 
-  it 'returns 422 response when the project could not be imported' do
+  it 'returns 422 response with the base error when the project could not be imported' do
+    project = build(:project)
+    error_message = 'This is an error'
+    project.errors.add(:base, error_message)
+
     allow(Gitlab::LegacyGithubImport::ProjectCreator)
       .to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider)
-        .and_return(double(execute: build(:project)))
+        .and_return(double(execute: project))
 
     post :create, format: :json
 
     expect(response).to have_gitlab_http_status(422)
+    expect(json_response['errors']).to eq(error_message)
+  end
+
+  it 'returns 422 response with a combined error when the project could not be imported' do
+    project = build(:project)
+    project.errors.add(:name, 'is invalid')
+    project.errors.add(:path, 'is old')
+
+    allow(Gitlab::LegacyGithubImport::ProjectCreator)
+      .to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider)
+        .and_return(double(execute: project))
+
+    post :create, format: :json
+
+    expect(response).to have_gitlab_http_status(422)
+    expect(json_response['errors']).to eq('Name is invalid, Path is old')
   end
 
   context "when the repository owner is the provider user" do