TypeError：类Task的超类不匹配

Question

我有一个 Rails 项目并使用 RSpec 进行测试。最近，我在spec_helper.rb中添加了这个：

config.before(:suite) do
  Rails.application.load_tasks
end

如果我使用bundle exec rspec 在本地运行测试，一切都很好。但是当我尝试在 Travis CI 上做同样的事情时，命令会崩溃：

TypeError: superclass mismatch for class Task
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:9:in `<module:Rails>'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:8:in `<module:Sprockets>'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:7:in `<top (required)>'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:274:in `require'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:274:in `block in require'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:274:in `require'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/railtie.rb:163:in `block in <class:Railtie>'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:237:in `instance_exec'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:237:in `block in run_tasks_blocks'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:245:in `each'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:245:in `each_registered_block'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:237:in `run_tasks_blocks'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/application.rb:451:in `block in run_tasks_blocks'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/engine/railties.rb:13:in `each'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/engine/railties.rb:13:in `each'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/application.rb:451:in `run_tasks_blocks'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/engine.rb:453:in `load_tasks'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:194:in `public_send'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/railtie.rb:194:in `method_missing'
    from (irb):25
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/commands/console.rb:110:in `start'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/commands/console.rb:9:in `start'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/commands/commands_tasks.rb:68:in `console'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/railties-4.2.9/lib/rails/commands.rb:17:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

如果我调试 Travis 构建并手动启动 bundle exec rails c 并执行 Rails.application.load_tasks，也会发生同样的事情。

这可能是什么问题？任何线索将不胜感激！

Answer 1

TypeError: superclass mismatch 在您重新打开一个类并尝试为其重新定义超类时发生。这是一种强制此错误的方法：

class A; end
class B < A; end
class C; end
class B < C; end # raises error

由于这只发生在 Travis 环境中，如果可能的话，我会在那里调试它：

• 使用 vim nano 或类似的 CLI 编辑器打开 /home/travis/build/my_application/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb
• 将require 'pry'; binding.pry放在导致错误的行上方
• bundle install
• 重新运行您的测试代码
• 进入调试器并检查Task 的来源。因为你得到TypeError: superclass mismatch，Task 必须在重新打开它的行之前定义。 show-source Task 应该会告诉你它是在哪里定义的。