fixed support for DATABASE_URL for rake db tasks

Backport for #7521

- added tests to confirm establish_connection uses DATABASE_URL and
  Rails.env correctly even when no arguments are passed in.
- updated rake db tasks to support DATABASE_URL, and added tests to
  confirm correct behavior for these rake tasks.  (Removed
  establish_connection call from some tasks since in those cases
  the :environment task already made sure the function would be called)
- updated Resolver so that when it resolves the database url, it
  removes hash values with empty strings from the config spec (e.g.
  to support connection to postgresql when no username is specified).
- updated ResolverTest to use current_adapter? to check the type of
  the current adapter.

1 files changed, 36 insertions, 0 deletions

diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index cf6c4d8fc2..b4c9741b05 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -193,5 +193,41 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       assert_nil defined?(ActiveRecord::Base)
     end
+
+    test "active record establish_connection uses Rails.env if DATABASE_URL is not set" do
+      begin
+        require "#{app_path}/config/environment"
+        orig_database_url = ENV.delete("DATABASE_URL")
+        orig_rails_env, Rails.env = Rails.env, 'development'
+
+        ActiveRecord::Base.establish_connection
+
+        assert ActiveRecord::Base.connection
+        assert_match /#{ActiveRecord::Base.configurations[Rails.env]['database']}/, ActiveRecord::Base.connection_config[:database]
+      ensure
+        ActiveRecord::Base.remove_connection
+        ENV["DATABASE_URL"] = orig_database_url if orig_database_url
+        Rails.env = orig_rails_env if orig_rails_env
+      end
+    end
+
+    test "active record establish_connection uses DATABASE_URL even if Rails.env is set" do
+      begin
+        require "#{app_path}/config/environment"
+        orig_database_url = ENV.delete("DATABASE_URL")
+        orig_rails_env, Rails.env = Rails.env, 'development'
+        database_url_db_name = "db/database_url_db.sqlite3"
+        ENV["DATABASE_URL"] = "sqlite3://:@localhost/#{database_url_db_name}"
+
+        ActiveRecord::Base.establish_connection
+
+        assert ActiveRecord::Base.connection
+        assert_match /#{database_url_db_name}/, ActiveRecord::Base.connection_config[:database]
+      ensure
+        ActiveRecord::Base.remove_connection
+        ENV["DATABASE_URL"] = orig_database_url if orig_database_url
+        Rails.env = orig_rails_env if orig_rails_env
+      end
+    end
   end
 end