doc: fix README shared_context code given for testing

[esquinas]

Solves issue #182 "Example code for testing given in README produces NameError"

[esquinas]

Maybe in the future you could provide the test helper like this instead of in the README

# spec/support/shared_examples/axlsx.rb

require "caxlsx_rails/test_helper"
# ...

[straydogstudio]

@esquinas Do you know what Rails version this became effective in?

If it is new enough, it would be good to comment out the old line and indicate what version of Rails it is used in.

[esquinas]

@straydogstudio I think this is independent of the Rails version. We use this gem and it failed during CI/CD just by doing a dependabot update of caxlsx_rails from 0.6.3 to 0.6.4
Now, in older Rails versions, the AxlsxRails::TemplateHandle class is going to be available because it belongs to the gem, not to Rails.

[timdiggins]

@straydogstudio I can confirm same thing for me.

FYI The change to the namespace & name of the class came in #164

[esquinas]

@straydogstudio Sorry to insist, I write again just to make sure you are not waiting for me to solve the failed CI tests.

I am not solving them because the failed CI tests look like flaky setup stuff like this:

An error occurred while installing sqlite3 (1.6.9), and Bundler cannot continue.

In Gemfile.rails-5.2:
  sqlite3
Error: The process '/opt/hostedtoolcache/Ruby/2.4.10/x64/bin/bundle' failed with exit code 5

I think/hope the failures will go away if you re-run the Github actions. I do not have permissions to re-run them (or I cannot find where to click)

Thanks.

[straydogstudio]

@esquinas Yeah it does seem like flaky setup. It is always ruby 2.4. So far rerunning hasn't helped.

I'll add it anyway for now.