Create Rails::Generators::TestCase.

2 files changed, 225 insertions, 1 deletions

diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index a10d1c9fce..5e8c2730fd 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -272,7 +272,7 @@ module Rails
         # parameters.
         #
         def invoked?(args)
-          args.last.is_a?(Hash) && args.last.key?(:invocations)
+          args.last.is_a?(Hash) && (args.last.key?(:invocations) || args.last.key?(:destination_root))
         end
 
         # Use Rails default banner.
diff --git a/railties/lib/rails/generators/test_case.rb b/railties/lib/rails/generators/test_case.rb
new file mode 100644
index 0000000000..8918a4eb42
--- /dev/null
+++ b/railties/lib/rails/generators/test_case.rb
@@ -0,0 +1,224 @@
+require 'active_support/test_case'
+require 'active_support/core_ext/class/inheritable_attributes'
+require 'active_support/core_ext/hash/reverse_merge'
+require 'rails/generators'
+require 'fileutils'
+
+module Rails
+  module Generators
+    # Disable color in output. Easier to debug.
+    no_color!
+
+    # This class provides a TestCase for testing generators. To setup, you need
+    # just to configure the destination and set which generator is being tested:
+    #
+    #   class AppGeneratorTest < Rails::Generators::TestCase
+    #     tests AppGenerator
+    #     destination File.expand_path("../tmp", File.dirname(__FILE__))
+    #   end
+    #
+    # If you want to ensure your destination root is clean before running each test,
+    # you can set a setup callback:
+    #
+    #   class AppGeneratorTest < Rails::Generators::TestCase
+    #     tests AppGenerator
+    #     destination File.expand_path("../tmp", File.dirname(__FILE__))
+    #     setup :prepare_destination
+    #   end
+    #
+    class TestCase < ActiveSupport::TestCase
+      include FileUtils
+
+      extlib_inheritable_accessor :destination_root, :current_path, :instance_writer => false
+      extlib_inheritable_accessor :generator_class
+
+      # Generators frequently change the current path using +FileUtils.cd+.
+      # So we need to store the path at file load and revert back to it after each test.
+      self.current_path = File.expand_path(Dir.pwd)
+
+      setup :destination_root_is_set?, :ensure_current_path
+      teardown :ensure_current_path
+
+      # Sets which generator should be tested:
+      #
+      #   tests AppGenerator
+      #
+      def self.tests(klass)
+        self.generator_class = klass
+      end
+
+      # Sets the destination of generator files:
+      #
+      #   destination File.expand_path("../tmp", File.dirname(__FILE__))
+      #
+      def self.destination(path)
+        self.destination_root = path
+      end
+
+      # Captures the given stream and returns it:
+      #
+      #   stream = capture(:stdout){ puts "Cool" }
+      #   stream #=> "Cool\n"
+      #
+      def capture(stream)
+        begin
+          stream = stream.to_s
+          eval "$#{stream} = StringIO.new"
+          yield
+          result = eval("$#{stream}").string
+        ensure 
+          eval("$#{stream} = #{stream.upcase}")
+        end
+
+        result
+      end
+      alias :silence :capture
+
+      # Asserts a given file exists. You need to supply an absolute path or a path relative
+      # to the configured destination:
+      #
+      #   assert_file "config/environment.rb"
+      #
+      # You can also give extra arguments. If the argument is a regexp, it will check if the
+      # regular expression matches the given file content. If it's a string, it compares the
+      # file with the given string:
+      #
+      #   assert_file "config/environment.rb", /initialize/
+      #
+      # Finally, when a block is given, it yields the file content:
+      #
+      #   assert_file "app/controller/products_controller.rb" do |controller|
+      #     assert_instance_method :index, content do |index|
+      #       assert_match /Product\.all/, index
+      #     end
+      #   end
+      #
+      def assert_file(relative, *contents)
+        absolute = File.expand_path(relative, destination_root)
+        assert File.exists?(absolute), "Expected file #{relative.inspect} to exist, but does not"
+
+        read = File.read(absolute) if block_given? || !contents.empty?
+        yield read if block_given?
+
+        contents.each do |content|
+          case content
+            when String
+              assert_equal content, read
+            when Regexp
+              assert_match content, read
+          end
+        end
+      end
+      alias :assert_directory :assert_file
+
+      # Asserts a given file does not exist. You need to supply an absolute path or a
+      # path relative to the configured destination:
+      #
+      #   assert_no_file "config/random.rb"
+      #
+      def assert_no_file(relative)
+        absolute = File.expand_path(relative, destination_root)
+        assert !File.exists?(absolute), "Expected file #{relative.inspect} to not exist, but does"
+      end
+      alias :assert_no_directory :assert_no_file
+
+      # Asserts a given file does not exist. You need to supply an absolute path or a
+      # path relative to the configured destination:
+      #
+      #   assert_migration "db/migrate/create_products.rb"
+      #
+      # This method manipulates the given path and tries to find any migration which 
+      # matches the migration name. For example, the call above is converted to:
+      # 
+      #   assert_file "db/migrate/003_create_products.rb"
+      #
+      # Consequently, assert_migration accepts the same arguments has assert_file.
+      #
+      def assert_migration(relative, *contents, &block)
+        file_name = migration_file_name(relative)
+        assert file_name, "Expected migration #{relative} to exist, but was not found"
+        assert_file file_name, *contents, &block
+      end
+
+      # Asserts a given migration does not exist. You need to supply an absolute path or a
+      # path relative to the configured destination:
+      #
+      #   assert_no_file "config/random.rb"
+      #
+      def assert_no_migration(relative)
+        file_name = migration_file_name(relative)
+        assert_nil file_name, "Expected migration #{relative} to not exist, but found #{file_name}"
+      end
+
+      # Asserts the given class method exists in the given content. This method does not detect
+      # class methods inside (class << self), only class methods which starts with "self.".
+      # When a block is given, it yields the content of the method.
+      #
+      #   assert_migration "db/migrate/create_products.rb" do |migration|
+      #     assert_class_method :up, migration do |up|
+      #       assert_match /create_table/, up
+      #     end
+      #   end
+      #
+      def assert_class_method(method, content, &block)
+        assert_instance_method "self.#{method}", content, &block
+      end
+
+      # Asserts the given method exists in the given content. When a block is given,
+      # it yields the content of the method.
+      #
+      #   assert_file "app/controller/products_controller.rb" do |controller|
+      #     assert_instance_method :index, content do |index|
+      #       assert_match /Product\.all/, index
+      #     end
+      #   end
+      #
+      def assert_instance_method(method, content)
+        assert content =~ /def #{method}(\(.+\))?(.*?)\n  end/m, "Expected to have method #{method}"
+        yield $2.strip if block_given?
+      end
+      alias :assert_method :assert_instance_method
+
+      # Runs the generator configured for this class. The first argument is an array like
+      # command line arguments:
+      #
+      #   class AppGeneratorTest < Rails::Generators::TestCase
+      #     tests AppGenerator
+      #     destination File.expand_path("../tmp", File.dirname(__FILE__))
+      #     teardown :cleanup_destination_root
+      #
+      #     test "database.yml is not created when skipping activerecord" do
+      #       run_generator %w(myapp --skip-activerecord)
+      #       assert_no_file "config/database.yml"
+      #     end
+      #   end
+      #
+      # You can provide a configuration hash as second argument. This method returns the output
+      # printed by the generator.
+      def run_generator(args=[], config={})
+        capture(:stdout) { self.generator_class.start args, config.reverse_merge(:destination_root => destination_root) }
+      end
+
+      protected
+
+        def destination_root_is_set? #:nodoc:
+          raise "You need to configure your Rails::Generators::TestCase destination root." unless destination_root
+        end
+
+        def ensure_current_path #:nodoc:
+          cd current_path
+        end
+
+        def prepare_destination
+          rm_rf(destination_root)
+          mkdir_p(destination_root)
+        end
+
+        def migration_file_name(relative) #:nodoc:
+          absolute = File.expand_path(relative, destination_root)
+          dirname, file_name = File.dirname(absolute), File.basename(absolute).sub(/\.rb$/, '')
+          Dir.glob("#{dirname}/[0-9]*_*.rb").grep(/\d+_#{file_name}.rb$/).first
+        end
+    end
+  end
+end
\ No newline at end of file