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# Contains the enhancements to assist in testing plugins. See Engines::Testing

# for more details.

require 'test/unit'

require 'tmpdir'

require 'fileutils'

# In most cases, Rails' own plugin testing mechanisms are sufficient. However, there

# are cases where plugins can be given a helping hand in the testing arena. This module 

# contains some methods to assist when testing plugins that contain fixtures.

# 

# == Fixtures and plugins

#

# Since Rails' own fixtures method is fairly strict about where files can be loaded from,

# the simplest approach when running plugin tests with fixtures is to simply copy all

# fixtures into a single temporary location and inform the standard Rails mechanism to

# use this directory, rather than RAILS_ROOT/test/fixtures.

#

# The Engines::Testing#setup_plugin_fixtures method does this, copying all plugin fixtures

# into the temporary location before and tests are performed. This behaviour is invoked

# the the rake tasks provided by the Engines plugin, in the "test:plugins" namespace. If

# necessary, you can invoke the task manually.

#

# If you wish to take advantage of this, add a call to the Engines::Testing.set_fixture_path

# method somewhere before your tests (in a test_helper file, or above the TestCase itself).

#

# = Testing plugins

#

# Normally testing a plugin will require that Rails is loaded, unless you are including

# a skeleton Rails environment or set of mocks within your plugin tests. If you require

# the Rails environment to be started, you must ensure that this actually happens; while

# it's not obvious, your tests do not automatically run with Rails loaded.

#

# The simplest way to setup plugin tests is to include a test helper with the following

# contents:

#

#   # Load the normal Rails helper. This ensures the environment is loaded

#   require File.expand_path(File.dirname(__FILE__) + '/../../../../test/test_helper')

#   # Ensure that we are using the temporary fixture path

#   Engines::Testing.set_fixture_path

#

# Then run tests using the provided tasks (<tt>test:plugins</tt>, or the tasks that the engines

# plugin provides - <tt>test:plugins:units</tt>, etc.).

#

# Alternatively, you can explicitly load the environment by adpating the contents of the

# default <tt>test_helper</tt>:

#

#   ENV["RAILS_ENV"] = "test"

#   # Note that we are requiring config/environment from the root of the enclosing application.

#   require File.expand_path(File.dirname(__FILE__) + "/../../../../config/environment")

#   require 'test_help'

#

module Engines::Testing

  mattr_accessor :temporary_fixtures_directory

  self.temporary_fixtures_directory = FileUtils.mkdir_p(File.join(Dir.tmpdir, "rails_fixtures"))

  # Copies fixtures from plugins and the application into a temporary directory 

  # (Engines::Testing.temporary_fixtures_directory). 

  # 

  # If a set of plugins is not given, fixtures are copied from all plugins in order 

  # of precedence, meaning that plugins can 'overwrite' the fixtures of others if they are 

  # loaded later; the application's fixtures are copied last, allowing any custom fixtures

  # to override those in the plugins. If no argument is given, plugins are loaded via

  # PluginList#by_precedence.

  #

  # This method is called by the engines-supplied plugin testing rake tasks

  def self.setup_plugin_fixtures(plugins = Engines.plugins.by_precedence)

    # First, clear the directory

    Dir.glob("#{self.temporary_fixtures_directory}/*.yml").each{|fixture| File.delete(fixture)}

    # Copy all plugin fixtures, and then the application fixtures, into this directory

    plugins.each do |plugin| 

      plugin_fixtures_directory =  File.join(plugin.directory, "test", "fixtures")

      plugin_app_directory =  File.join(plugin.directory, "app")

      if File.directory?(plugin_app_directory) && File.directory?(plugin_fixtures_directory)

        Engines.mirror_files_from(plugin_fixtures_directory, self.temporary_fixtures_directory)

      end

    end

    Engines.mirror_files_from(File.join(RAILS_ROOT, "test", "fixtures"),

                              self.temporary_fixtures_directory)

  end

  # Sets the fixture path used by Test::Unit::TestCase to the temporary

  # directory which contains all plugin fixtures.

  def self.set_fixture_path

    ActiveSupport::TestCase.fixture_path = self.temporary_fixtures_directory

    $LOAD_PATH.unshift self.temporary_fixtures_directory

  end

  # overridden test should be in test/{unit,functional,integration}/{plugin_name}/{test_name}

  def self.override_tests_from_app

    filename = caller.first.split(":").first

    plugin_name = filename.split("/")[-4]

    test_kind = filename.split("/")[-2]

    override_file = File.expand_path(File.join(File.dirname(filename), "..", "..", "..", "..", "..", "test", 

                                               test_kind, plugin_name, File.basename(filename)))

    load(override_file) if File.exist?(override_file)

  end

end