Merge branch '22348-gitea-importer' into 'master'

It adds a brand new importer for Gitea!

This is a continuation of !6945 started by @bkc.

Gitea aims to be 100% GitHub-compatible but there's a few differences:

- Gitea is not an OAuth provider (yet): https://github.com/go-gitea/gitea/issues/27
  - This means we cannot map Gitea users given an assignee ID => assignees are not set on imported issues and merge requests
- No releases API for now: https://github.com/go-gitea/gitea/issues/330
- API version is `v1` (GitHub is `v3`)
- The IID field for milestones is `id` compared to `number` in GitHub.
- Issues, PRs, milestones, labels don't have a `url` field (the importer now fallback to `''` in that case)

**Known issues:**

- Comments are not imported because comments JSON always have a blank `html_url`/`issue_url`/`pull_request_url`, so the IID cannot be extracted and the issuable cannot be found... :( This is tracked in https://github.com/go-gitea/gitea/issues/401, and solved by https://github.com/gogits/gogs/pull/3624 but this needs to be submitted / merged in Gitea.

This is noted in the documentation.

## Are there points in the code the reviewer needs to double check?

1. I've made `Import::GiteaController` inherit from `Import::GithubController` since both controllers should be identical in the long-term and their current differences are small.
1. I've added a base `IssuableFormatter` class from which `IssueFormatter` & `PullRequestFormatter` inherit
1. I've added shared examples for GitHub/Gitea importer classes
1. I've made `Gitlab::ImportSources` more robust and tested! :christmas_tree: 
1. I've added routing specs for import routes! :christmas_tree: 

Closes #22348

See merge request !8116

2 files changed, 242 insertions, 0 deletions

diff --git a/spec/support/controllers/githubish_import_controller_shared_context.rb b/spec/support/controllers/githubish_import_controller_shared_context.rb
new file mode 100644
index 00000000000..e71994edec6
--- /dev/null
+++ b/spec/support/controllers/githubish_import_controller_shared_context.rb
@@ -0,0 +1,10 @@
+shared_context 'a GitHub-ish import controller' do
+  let(:user) { create(:user) }
+  let(:token) { "asdasd12345" }
+  let(:access_params) { { github_access_token: token } }
+
+  before do
+    sign_in(user)
+    allow(controller).to receive(:"#{provider}_import_enabled?").and_return(true)
+  end
+end
diff --git a/spec/support/controllers/githubish_import_controller_shared_examples.rb b/spec/support/controllers/githubish_import_controller_shared_examples.rb
new file mode 100644
index 00000000000..d0fd2d52004
--- /dev/null
+++ b/spec/support/controllers/githubish_import_controller_shared_examples.rb
@@ -0,0 +1,232 @@
+# Specifications for behavior common to all objects with an email attribute.
+# Takes a list of email-format attributes and requires:
+# - subject { "the object with a attribute= setter"  }
+#   Note: You have access to `email_value` which is the email address value
+#         being currently tested).
+
+def assign_session_token(provider)
+  session[:"#{provider}_access_token"] = 'asdasd12345'
+end
+
+shared_examples 'a GitHub-ish import controller: POST personal_access_token' do
+  let(:status_import_url) { public_send("status_import_#{provider}_url") }
+
+  it "updates access token" do
+    token = 'asdfasdf9876'
+
+    allow_any_instance_of(Gitlab::GithubImport::Client).
+      to receive(:user).and_return(true)
+
+    post :personal_access_token, personal_access_token: token
+
+    expect(session[:"#{provider}_access_token"]).to eq(token)
+    expect(controller).to redirect_to(status_import_url)
+  end
+end
+
+shared_examples 'a GitHub-ish import controller: GET new' do
+  let(:status_import_url) { public_send("status_import_#{provider}_url") }
+
+  it "redirects to status if we already have a token" do
+    assign_session_token(provider)
+    allow(controller).to receive(:logged_in_with_provider?).and_return(false)
+
+    get :new
+
+    expect(controller).to redirect_to(status_import_url)
+  end
+
+  it "renders the :new page if no token is present in session" do
+    get :new
+
+    expect(response).to render_template(:new)
+  end
+end
+
+shared_examples 'a GitHub-ish import controller: GET status' do
+  let(:new_import_url) { public_send("new_import_#{provider}_url") }
+  let(:user) { create(:user) }
+  let(:repo) { OpenStruct.new(login: 'vim', full_name: 'asd/vim') }
+  let(:org) { OpenStruct.new(login: 'company') }
+  let(:org_repo) { OpenStruct.new(login: 'company', full_name: 'company/repo') }
+  let(:extra_assign_expectations) { {} }
+
+  before do
+    assign_session_token(provider)
+  end
+
+  it "assigns variables" do
+    project = create(:empty_project, import_type: provider, creator_id: user.id)
+    stub_client(repos: [repo, org_repo], orgs: [org], org_repos: [org_repo])
+
+    get :status
+
+    expect(assigns(:already_added_projects)).to eq([project])
+    expect(assigns(:repos)).to eq([repo, org_repo])
+    extra_assign_expectations.each do |key, value|
+      expect(assigns(key)).to eq(value)
+    end
+  end
+
+  it "does not show already added project" do
+    project = create(:empty_project, import_type: provider, creator_id: user.id, import_source: 'asd/vim')
+    stub_client(repos: [repo], orgs: [])
+
+    get :status
+
+    expect(assigns(:already_added_projects)).to eq([project])
+    expect(assigns(:repos)).to eq([])
+  end
+
+  it "handles an invalid access token" do
+    allow_any_instance_of(Gitlab::GithubImport::Client).
+      to receive(:repos).and_raise(Octokit::Unauthorized)
+
+    get :status
+
+    expect(session[:"#{provider}_access_token"]).to be_nil
+    expect(controller).to redirect_to(new_import_url)
+    expect(flash[:alert]).to eq("Access denied to your #{Gitlab::ImportSources.title(provider.to_s)} account.")
+  end
+end
+
+shared_examples 'a GitHub-ish import controller: POST create' do
+  let(:user) { create(:user) }
+  let(:provider_username) { user.username }
+  let(:provider_user) { OpenStruct.new(login: provider_username) }
+  let(:provider_repo) do
+    OpenStruct.new(
+      name: 'vim',
+      full_name: "#{provider_username}/vim",
+      owner: OpenStruct.new(login: provider_username)
+    )
+  end
+
+  before do
+    stub_client(user: provider_user, repo: provider_repo)
+    assign_session_token(provider)
+  end
+
+  context "when the repository owner is the provider user" do
+    context "when the provider user and GitLab user's usernames match" do
+      it "takes the current user's namespace" do
+        expect(Gitlab::GithubImport::ProjectCreator).
+          to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider).
+            and_return(double(execute: true))
+
+        post :create, format: :js
+      end
+    end
+
+    context "when the provider user and GitLab user's usernames don't match" do
+      let(:provider_username) { "someone_else" }
+
+      it "takes the current user's namespace" do
+        expect(Gitlab::GithubImport::ProjectCreator).
+          to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider).
+            and_return(double(execute: true))
+
+        post :create, format: :js
+      end
+    end
+  end
+
+  context "when the repository owner is not the provider user" do
+    let(:other_username) { "someone_else" }
+
+    before do
+      provider_repo.owner = OpenStruct.new(login: other_username)
+      assign_session_token(provider)
+    end
+
+    context "when a namespace with the provider user's username already exists" do
+      let!(:existing_namespace) { create(:namespace, name: other_username, owner: user) }
+
+      context "when the namespace is owned by the GitLab user" do
+        it "takes the existing namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).with(provider_repo, provider_repo.name, existing_namespace, user, access_params, type: provider).
+              and_return(double(execute: true))
+
+          post :create, format: :js
+        end
+      end
+
+      context "when the namespace is not owned by the GitLab user" do
+        before do
+          existing_namespace.owner = create(:user)
+          existing_namespace.save
+        end
+
+        it "creates a project using user's namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider).
+              and_return(double(execute: true))
+
+          post :create, format: :js
+        end
+      end
+    end
+
+    context "when a namespace with the provider user's username doesn't exist" do
+      context "when current user can create namespaces" do
+        it "creates the namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).and_return(double(execute: true))
+
+          expect { post :create, target_namespace: provider_repo.name, format: :js }.to change(Namespace, :count).by(1)
+        end
+
+        it "takes the new namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).with(provider_repo, provider_repo.name, an_instance_of(Group), user, access_params, type: provider).
+            and_return(double(execute: true))
+
+          post :create, target_namespace: provider_repo.name, format: :js
+        end
+      end
+
+      context "when current user can't create namespaces" do
+        before do
+          user.update_attribute(:can_create_group, false)
+        end
+
+        it "doesn't create the namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).and_return(double(execute: true))
+
+          expect { post :create, format: :js }.not_to change(Namespace, :count)
+        end
+
+        it "takes the current user's namespace" do
+          expect(Gitlab::GithubImport::ProjectCreator).
+            to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider).
+            and_return(double(execute: true))
+
+          post :create, format: :js
+        end
+      end
+    end
+
+    context 'user has chosen a namespace and name for the project' do
+      let(:test_namespace) { create(:namespace, name: 'test_namespace', owner: user) }
+      let(:test_name) { 'test_name' }
+
+      it 'takes the selected namespace and name' do
+        expect(Gitlab::GithubImport::ProjectCreator).
+          to receive(:new).with(provider_repo, test_name, test_namespace, user, access_params, type: provider).
+            and_return(double(execute: true))
+
+        post :create, { target_namespace: test_namespace.name, new_name: test_name, format: :js }
+      end
+
+      it 'takes the selected name and default namespace' do
+        expect(Gitlab::GithubImport::ProjectCreator).
+          to receive(:new).with(provider_repo, test_name, user.namespace, user, access_params, type: provider).
+            and_return(double(execute: true))
+
+        post :create, { new_name: test_name, format: :js }
+      end
+    end
+  end
+end