feature request: Devel::Cover API to work with collected coverage

[happy-barney]

It will be nice to have tooling to work with coverage data inside tests.

Expected usage:

• to test coverage of given function/method

  test_coverage ('Foo::bar', code => min (0.9), branch => min (0.9))

• list used coverage for given test, eg to build dependency tree between source code and test cases that covers it (static but better than nothing)

[pjcj]

The first point is interesting. I suspect we could make something work, but perhaps not quite in the form that you have suggested.

I wonder whether something like test_coverage(sub { ... }, statement => 0.9, branch => 0.8) would work?

The second point is planned, and partly implemented. The Sort report, such as it is, makes use of this functionality.

[happy-barney]

Intended usage: there is a package providing REST resource with methods like GET, POST. Tests in project are organized by public api, for example REST-resource-POST.t.

In this case it will be nice to say: this test suite should cover almost 100% of method, let set list_users. That may call other methods, but I don't care about those number, can be even 1 path out of 100

so if syntax will be

test_coverage \&My::Package::list_users, ...;

then it will work for me

[pjcj]

The tricky part is knowing when to start collecting coverage, and when to stop and see what the values are.

Stopping is pretty easy - it has to be when the function is called. But the starting is harder. That's why my suggestion works - the coverage is over whatever is in the sub.

Let me have a think about it...

[happy-barney]

hmm, ok, I got it ... so what about

my $coverdb = cover { ... };

test_coverage $coverdb, 'Foo::Bar::baz', statement ...

or

test_coverage { ... },
   expect_statement_coverage ('Foo::Bar::baz') > 100,
   expect_path_that_died ('Foo::Bar::Support::baz'),
   expect_path_that_lived ('Foo::Bar::Support::baz'),
   ...