test_runner: add code coverage support to spec reporter

[richiemccoll]

What is the problem this feature will solve?

Currently the test runner supports code coverage with the default tap reporter behind the experimental flag.

// node --experimental-test-coverage fixtures.js
running first
TAP version 13
# Subtest: parent block
    # Subtest: child subtest 1 should run
    ok 1 - child subtest 1 should run
      ---
      duration_ms: 1.452902
      ...
    1..1
ok 1 - parent block
  ---
  duration_ms: 6.648896
  ...
1..1
# tests 1
# pass 1
# fail 0
# cancelled 0
# skipped 0
# todo 0
# duration_ms 31.322558
# start of coverage report
# file | line % | branch % | funcs % | uncovered lines
# fixtures.js | 100.00 | 100.00 | 100.00 | 
# all files | 100.00 | 100.00 | 100.00 |
# end of coverage report

When specifying the spec reporter (node --test-reporter=spec --experimental-test-coverage), there is no output.

▶ parent block
  ✔ child subtest 1 should run (1.524443ms)
▶ parent block (5.802161ms)
ℹ tests 1
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 28.888102

What is the feature you are proposing to solve the problem?

Add code coverage support by handling the test:coverage event inside the spec reporter.

What alternatives have you considered?

No response

[piranna]

As said at #47032, since spec reporter is intended to provide an user readable output, I propose to use Istambul text reporter, that's the same being used by Jest, NYC, and by extension also c8.

[pulkit-30]

As said at #47032, since spec reporter is intended to provide an user readable output, I propose to use Istambul text reporter, that's the same being used by Jest, NYC, and by extension also c8.

Hey @piranna
Thanks for the suggestions, I will update my pr asap 🚀

[piranna]

Thanks for the suggestions, I will update my pr asap

You are welcome :-)