将应用程序从 Rails 5.2 升级到 6.0 后运行 rspec 时的 PG::ConnectionBad(connection is closed)答案

【问题标题】：PG::ConnectionBad(connection is closed) when running rspec after upgrading application from Rails 5.2 to 6.0将应用程序从 Rails 5.2 升级到 6.0 后运行 rspec 时的 PG::ConnectionBad(connection is closed)
【发布时间】：2021-02-21 06:00:50
【问题描述】：

我尝试将我的应用程序从 Rails 5.2 升级到 6.0，升级后运行 rspec 会引发错误 PG::ConnectionBad: connection is closed。

错误是由rails_helper.rb中的表达式ActiveRecord::Migration.maintain_test_schema!引起的，错误如下，

root@00de976cbbd4:/app# rspec

An error occurred while loading rails_helper.
Failure/Error: ActiveRecord::Migration.maintain_test_schema!

PG::ConnectionBad:
  connection is closed
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/postgresql/quoting.rb:21:in `escape_string'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/postgresql/quoting.rb:21:in `quote_string'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/abstract/quoting.rb:220:in `_quote'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/postgresql/quoting.rb:144:in `_quote'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/abstract/quoting.rb:18:in `quote'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:750:in `quoted_scope'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:727:in `data_source_sql'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/connection_adapters/abstract/schema_statements.rb:62:in `table_exists?'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/internal_metadata.rb:32:in `table_exists?'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/tasks/database_tasks.rb:347:in `schema_up_to_date?'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:594:in `block in load_schema_if_pending!'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:593:in `all?'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:593:in `load_schema_if_pending!'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:614:in `block in maintain_test_schema!'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:867:in `suppress_messages'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:619:in `method_missing'
# /usr/local/bundle/gems/activerecord-6.0.3.5/lib/active_record/migration.rb:614:in `maintain_test_schema!'
# ./spec/rails_helper.rb:30:in `<top (required)>'
No examples found.
No examples found.

我可以在控制台中启动RAILS_ENV=test rails c 并运行ActiveRecord::Migration.maintain_test_schema! 而不会出错。并且还尝试将 rspec 从3.10.1 升级到4-0-dev，但仍然出现相同的错误。提前致谢。

【问题讨论】：

标签： ruby-on-rails-6

【解决方案1】：

最后我创建了一个新的 rails 6 应用程序，然后逐个文件复制以检查导致此错误的原因，结果发现在我的 spec/support 文件夹中有一个文件 shared_db_conntection.rb 具有以下内容，该文件是从这个博客http://blog.plataformatec.com.br/2011/12/three-tips-to-improve-the-performance-of-your-test-suite/

class ActiveRecord::Base
  mattr_accessor :shared_connection
  @@shared_connection = nil

  def self.connection
    @@shared_connection || retrieve_connection
  end
end

ActiveRecord::Base.shared_connection = ActiveRecord::Base.connection

删除这个文件后就没有这个错误了

【讨论】：