Write BoundedContext docs

[fidel]

There's no docs currently describing the purpose and philosophy of BoundedContext gem. Questions which can be covered:

• why it generates directory on the top level of a Rails app (unusual)
• explain the directory structure (http://guides.rubygems.org/patterns/#consistent-naming can be helpful)
• does it work with bin/spec command
• etc.

Related: #186

[andriytyurnikov]

Running generator rails g bounded_context:bounded_context PlatformCore generates files

platform_core/lib/platform_core.rb
platform_core/test/test_helper.rb

After adding some code

# platform_core/lib/platform_core.rb
module PlatformCore
  CONSTANT = 42 # constant to reference from rails integration tests
end

# platform_core/test/test_helper.rb
require_relative '../lib/platform_core'

fail "Not running with rails test"

# test/integration/signup_stories_test.rb
test "bounded context is accessible" do
    assert defined?(PlatformCore::CONSTANT)
end

and running rails test

Reveals few consequences of current design choices:

1. no failure from platform_core/test/test_helper.rb - BC test does not participate in rails test tasks
2. integration test failing

Failure:
SigninStoriesTest#test_bounded_context_is_accessible

Not sure if @paneq had a point in #186 On a separate note, running rails console and

Running via Spring preloader in process 25272
Loading development environment (Rails 5.1.5)
irb(main):001:0> PlatformCore::CONSTANT
=> 42
irb(main):002:0> 

Which means that code is loaded by console

[paneq]

integration test failing

do you use code preloading in test env?

does that work:

# test/integration/signup_stories_test.rb
test "bounded context is accessible" do
    PlatformCore::CONSTANT
    assert defined?(PlatformCore::CONSTANT)
end

?

[andriytyurnikov]

@paneq , yes, this workaround works, but rails models have better class visibility then BC, as models don't need such workarounds.

I'll cross-post question. Are bounded context independent/isolated from environment?

[andriytyurnikov]

"I distinguish between infrastructure isolation (they can share EventStore, DBs, app server, gems) and conceptual, business isolation." @paneq , well, here we have small differences, as I would prefer at least minimal friction for those, who trying to brake boundaries.

[paneq]

yes, this workaround works

what workaround? Are we talking about:

test "bounded context is accessible" do
    PlatformCore::CONSTANT
    assert defined?(PlatformCore::CONSTANT)
end

? That's not a workaruond. That's Rails lazy autoloading in work. I depends on what you have as config.eager_load = false in config/environments/test.rb. PlatformCore is lazily loaded only when you ask in your code for it. Example:

irb(main):002:0> defined?(Product)
=> nil

irb(main):003:0> Product
=> Product(id: integer, 

irb(main):004:0> defined?(Product)
=> "constant"

but rails models have better class visibility then BC

I don't understand what that means.

P.S. This issue is about Write BoundedContext docs