Scope is considerated "not ok" by simplecov-rcov when it is divided in two lines

[robsonagapito]

I have a code and I declare a scope, as line bellow:

scope :with_snapshot_histories,
-> { where(SCOPE_STR) }

In this case simplecov-rcov return "NOT OK", but if I declare scope in one line the result becomes OK.

scope :with_snapshot_histories, -> { where(SCOPE_STR) }

This situation also happens when I have a block (bellow):

NOT OK:
scope :service_codes_by_login, (lambda do |login|
joins(:account)
.where(accounts: {login: "#{login}/#{login}"})
.select(:service_code)
end)

OK:
scope :service_codes_by_login, (lambda do |login| joins(:account).where(accounts: {login: "#{login}/#{login}"}).select(:service_code) end)

Is this a problem? Or is this a expected comportment?

This situation affect the result of our coverage.

Code in 2 lines:

Result (2 lines) - 85.58% / 73.03 :

Code in 1 line:

Result (1 line) - 85.64% / 73.15%

Coverage's difference:
Result (2 lines) - 85.58% / 73.03%
Result (1 line) - 85.64% / 73.15%

PS: Images are gem SIMPLECOV-RCOV, but I tested with SIMPLECOV and happens the same.

[bf4]

Offhand, it sounds like a bug in the Coverage module that we may be able to work around with some clever trick.

[xaviershay]

Is the lambda/block actually being executed? If not, that would explain this behaviour to me.

[robsonagapito]

Lambda/block really not being executed... but we can see a false positive in this case, because when it is in one line returns ok, but not being executed the complete line. I believe that it considers the line beginnings ok and ignores the "block", indifferent if executed or not.

[bf4]

Actually with C0 coverage it is correct as it only checks that the line was executed or evaulated at load :) and Coverage only does C0. :)

[robsonagapito]

But, if I have a class with 20 scopes, all scopes with only one line to load, and no test, I have 100% of coverage, correct? This coverage would be a false positive?

[xaviershay]

yep, but there's nothing we can do about it. The underlying coverage library only provides line coverage, not branch coverage.

[bf4]

@robinroestenburg It's a common misunderstanding of SimpleCov. It's advertised as a test coverage tool, but practically it just uses the Ruby Coverage module to track which lines of a file are run and how many times. Since a method is only tracked when it's run, you can tell it's been called, so, during testing, it correlates with being tested.

[robinroestenburg]

@bf4 think you meant @robsonagapito? 😉