### Basic RSpec Test for Rails Generator

Source: https://github.com/stevehodgkiss/generator_spec/blob/master/README.md

Demonstrates a basic RSpec test file for a Rails generator. It sets the destination path, defines generator arguments, prepares the destination directory, runs the generator, and asserts the creation of a specific file with expected content.

```ruby
# spec/lib/generators/test/test_generator_spec.rb

require "generator_spec"

describe TestGenerator, type: :generator do
  destination File.expand_path("../../tmp", __FILE__)
  arguments %w(something)

  before(:all) do
    prepare_destination
    run_generator
  end

  it "creates a test initializer" do
    assert_file "config/initializers/test.rb", "# Initializer"
  end
end
```

--------------------------------

### RSpec Test with Custom Structure Matcher

Source: https://github.com/stevehodgkiss/generator_spec/blob/master/README.md

Shows how to use generator_spec's custom RSpec matcher for asserting file structures. This approach allows for detailed checks, including file existence, content presence, and absence of specific text within files, organized hierarchically.

```ruby
describe TestGenerator, "using custom matcher", type: :generator do
  destination File.expand_path("../../tmp", __FILE__)

  before do
    prepare_destination
    run_generator
  end

  specify do
    expect(destination_root).to have_structure {
      no_file "test.rb"
      directory "config" do
        directory "initializers" do
          file "test.rb" do
            contains "# Initializer"
            does_not_contain "Something else"
          end
        end
      end
      directory "db" do
        directory "migrate" do
          file "123_create_tests.rb"
          migration "create_tests" do
            contains "class TestMigration"
            does_not_contain "Something else"
          end
        end
      end
    }
  end
end
```

--------------------------------

### Add generator_spec Gem to Gemfile

Source: https://github.com/stevehodgkiss/generator_spec/blob/master/README.md

Include the generator_spec gem in your test group within the Gemfile to enable its functionality for testing Rails generators. This is a prerequisite for using the gem's features.

```ruby
group :test do
  gem "generator_spec"
end
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.