Add tests for `gitlab-backup-cli` thor application

gems/gitlab-backup-cli/spec/spec_helper.rb

 # frozen_string_literal: true
 
+require 'thor'
 require "gitlab/backup/cli"
 require 'tmpdir'
 require 'fileutils'
 require 'factory_bot'
+require 'gitlab/rspec/next_instance_of'
 
 # Load spec support code
 Dir['spec/support/**/*.rb'].each { |f| load f }

gems/gitlab-backup-cli/spec/support/helpers.rb

 # frozen_string_literal: true
 
-FakeContext = Struct.new(:gitlab_version, :backup_basedir, :env, keyword_init: true)
+module GitlabBackupHelpers
+  FakeContext = Struct.new(:gitlab_version, :backup_basedir, :env, keyword_init: true)
 
-def spec_path
-  Pathname.new(__dir__).join('..').expand_path
-end
+  def spec_path
+    Pathname.new(__dir__).join('..').expand_path
+  end
 
-def temp_path
-  spec_path.join('..', 'tmp').expand_path
-end
+  def temp_path
+    spec_path.join('..', 'tmp').expand_path
+  end
+
+  def stub_env(var, return_value)
+    stub_const('ENV', ENV.to_hash.merge(var => return_value))
+  end
 
-def stub_env(var, return_value)
-  stub_const('ENV', ENV.to_hash.merge(var => return_value))
+  def build_fake_context
+    FakeContext.new(
+      gitlab_version: '16.10',
+      backup_basedir: temp_path.join('backups'),
+      env: ActiveSupport::EnvironmentInquirer.new('test')
+    )
+  end
 end
 
-def build_fake_context
-  FakeContext.new(
-    gitlab_version: '16.10',
-    backup_basedir: temp_path.join('backups'),
-    env: ActiveSupport::EnvironmentInquirer.new('test')
-  )
+RSpec.configure do |config|
+  config.include GitlabBackupHelpers
+  # from gitlab-rspec
+  config.include NextInstanceOf
 end

gems/gitlab-backup-cli/spec/support/thor_spec_type.rb

+# frozen_string_literal: true
+
+RSpec.configure do |config|
+  config.define_derived_metadata(file_path: Regexp.new('spec/thor/')) do |metadata|
+    metadata[:type] = :thor
+  end
+
+  # Set terminal columns to be 120, so all specs behave the same no matter where it is being tested
+  config.before(:each, type: :thor) { stub_env('THOR_COLUMNS', 120) }
+end

gems/gitlab-backup-cli/spec/thor/gitlab_backup_cli_backup_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'gitlab-backup-cli backup subcommand', type: :thor do
+  subject(:cli) { Gitlab::Backup::Cli::Runner }
+
+  let(:backup_subcommand) { Gitlab::Backup::Cli::Commands::BackupSubcommand }
+  let(:context) { build_fake_context }
+
+  let(:expected_help_output) do
+    <<~COMMAND
+      Backup commands:
+        gitlab-backup-cli backup all             # Creates a backup including repositories, database and local files
+        gitlab-backup-cli backup help [COMMAND]  # Describe subcommands or one specific subcommand
+
+    COMMAND
+  end
+
+  context 'with gitlab-backup-cli backup' do
+    it 'returns a list of supported commands' do
+      expect { cli.start(%w[backup]) }.to output(expected_help_output).to_stdout
+    end
+  end
+
+  context 'with gitlab-backup-cli backup help' do
+    it 'returns a list of supported commands' do
+      expect { cli.start(%w[backup help]) }.to output(expected_help_output).to_stdout
+    end
+  end
+
+  context 'with gitlab-backup-cli backup all' do
+    it 'delegates backup execution to backup executor' do
+      # Simulate real execution
+      executor = Gitlab::Backup::Cli::BackupExecutor
+      expect_next_instance_of(executor) do |instance|
+        expect(instance).to receive(:execute)
+      end
+      expect_next_instance_of(backup_subcommand) do |instance|
+        expect(instance).to receive(:build_context).and_return(context)
+      end
+      expect(Gitlab::Backup::Cli).to receive(:rails_environment!)
+
+      expected_backup_output = /.*Starting GitLab backup.*Backup finished:.*/m
+      expect { cli.start(%w[backup all]) }.to output(expected_backup_output).to_stdout
+    end
+  end
+end

gems/gitlab-backup-cli/spec/thor/gitlab_backup_cli_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'gitlab-backup-cli commands', type: :thor do
+  subject(:cli) { Gitlab::Backup::Cli::Runner }
+
+  let(:expected_help_output) do
+    <<~COMMAND
+    GitLab Backup CLI commands:
+      gitlab-backup-cli backup          # Manage repositories, database and files backup creation
+      gitlab-backup-cli help [COMMAND]  # Describe available commands or one specific command
+      gitlab-backup-cli version         # Display the version information
+
+    COMMAND
+  end
+
+  describe 'Default behavior' do
+    it 'returns subcommand information with listed known methods' do
+      expect { cli.start([]) }.to output(expected_help_output).to_stdout
+    end
+  end
+
+  describe 'gitlab-backup-cli help' do
+    it 'returns subcommand information with listed known methods' do
+      expect { cli.start(%w[help]) }.to output(expected_help_output).to_stdout
+    end
+  end
+
+  describe 'gitlab-backup-cli version' do
+    it 'returns the current version' do
+      expect { cli.start(%w[version]) }.to output(
+        /GitLab Backup CLI \(#{Gitlab::Backup::Cli::VERSION}\)\n/o
+      ).to_stdout
+    end
+  end
+
+  describe 'gitlab-backup-cli backup' do
+    it 'returns a list of backup subcommands' do
+      expect { cli.start(%w[backup]) }.to output(/Backup commands:.*/).to_stdout
+    end
+  end
+end