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, 7 insertions, 1 deletions

diff --git a/config/initializers/1_settings.rb b/config/initializers/1_settings.rb
index ddea325c6ca..ee97b4e42b9 100644
--- a/config/initializers/1_settings.rb
+++ b/config/initializers/1_settings.rb
@@ -213,7 +213,7 @@ Settings.gitlab.default_projects_features['builds']             = true if Settin
 Settings.gitlab.default_projects_features['container_registry'] = true if Settings.gitlab.default_projects_features['container_registry'].nil?
 Settings.gitlab.default_projects_features['visibility_level']   = Settings.send(:verify_constant, Gitlab::VisibilityLevel, Settings.gitlab.default_projects_features['visibility_level'], Gitlab::VisibilityLevel::PRIVATE)
 Settings.gitlab['domain_whitelist'] ||= []
-Settings.gitlab['import_sources'] ||= %w[github bitbucket gitlab google_code fogbugz git gitlab_project]
+Settings.gitlab['import_sources'] ||= %w[github bitbucket gitlab google_code fogbugz git gitlab_project gitea]
 Settings.gitlab['trusted_proxies'] ||= []
 Settings.gitlab['no_todos_messages'] ||= YAML.load_file(Rails.root.join('config', 'no_todos_messages.yml'))
 
diff --git a/config/routes/import.rb b/config/routes/import.rb
index 89f3b3f6378..c378253bf15 100644
--- a/config/routes/import.rb
+++ b/config/routes/import.rb
@@ -6,6 +6,12 @@ namespace :import do
     get :jobs
   end
 
+  resource :gitea, only: [:create, :new], controller: :gitea do
+    post :personal_access_token
+    get :status
+    get :jobs
+  end
+
   resource :gitlab, only: [:create], controller: :gitlab do
     get :status
     get :callback