Tweaks to deal with empty repos (exercism#7894)

* Tweaks to deal with empty repos

* Fix test

Author: iHiD

app/commands/user/github_solution_syncer/create_pull_request.rb

@@ -10,20 +10,14 @@ def initialize(syncer, pr_title, pr_message, &commit_block)
     end
 
     def call
-      repo = syncer.repo_full_name
-      client = Octokit::Client.new(access_token: token)
-
-      base_branch = client.repository(repo).default_branch
-      base_sha = client.branch(repo, base_branch).commit.sha
-
       new_branch = "exercism-sync/#{SecureRandom.hex(8)}"
-      client.create_ref(repo, "heads/#{new_branch}", base_sha)
+      client.create_ref(repo_full_name, "heads/#{new_branch}", base_sha)
 
       commits_created = commit_block.(new_branch, token)
       return unless commits_created
 
       client.create_pull_request(
-        repo,
+        repo_full_name,
         base_branch,
         new_branch,
         pr_title,
@@ -34,9 +28,42 @@ def call
     private
     attr_reader :syncer, :pr_title, :pr_message, :commit_block
 
+    delegate :repo_full_name, to: :syncer
+
+    memoize
+    def base_sha
+      # This will raise if the branch doesn't exit
+      client.branch(repo_full_name, base_branch).commit.sha
+    rescue Octokit::NotFound
+      # If it doesn't, then this is a naked repo, so create it.
+      Dir.mktmpdir do |dir|
+        @path = dir
+
+        # No existing branch so create it
+        git "init", "-b", base_branch
+        git "commit", "--allow-empty", "-m", "Initial empty commit"
+        git "remote", "add", "origin", repo_url
+        git "push", "origin", base_branch
+      end
+
+      client.branch(repo_full_name, base_branch).commit.sha
+    end
+
     memoize
-    def token
-      GithubApp.generate_installation_token!(syncer.installation_id)
+    def base_branch = client.repository(repo_full_name).default_branch
+
+    def git(*args)
+      Dir.chdir(@path) do
+        system("git", *args, exception: true)
+      end
     end
+
+    def repo_url = "https://x-access-token:#{token}@github.com/#{repo_full_name}.git"
+
+    memoize
+    def token = GithubApp.generate_installation_token!(syncer.installation_id)
+
+    memoize
+    def client = Octokit::Client.new(access_token: token)
   end
 end

app/controllers/settings/github_syncer_controller.rb

@@ -2,7 +2,7 @@ class Settings::GithubSyncerController < ApplicationController
   skip_before_action :verify_authenticity_token, only: %i[update sync_everything sync_track sync_solution sync_iteration]
 
   def show
-    current_user.github_solution_syncer
+    @just_connected = !!params[:connected]
   end
 
   def update
@@ -68,7 +68,7 @@ def callback
       User::GithubSolutionSyncer::Create.(current_user, installation_id)
       redirect_to settings_github_syncer_path, notice: "GitHub connected successfully"
     rescue GithubSolutionSyncerCreationError => e
-      redirect_to settings_github_syncer_path, alert: e.message
+      redirect_to settings_github_syncer_path(connected: true), alert: e.message
     end
   end