[ci-visibility] [do not review - wip] Per test code coverage for `jest`

[juan-fernandez]

What does this PR do?

Read code coverage in jest if it's available (global.__coverage__) and reset the counters after every test. This results in a code coverage that is exclusive to the test. This works because tests (it clauses) are run sequentially within a test file.

After code coverage is formatted, it is exported through exportCoverage, a new function in AgentlessCiVisibilityExporter, which ends up using CIVisibilityCoverageEncoder encoder, which encodes the data in the expected format.

Additionally, a new dependency istanbul-lib-coverage is added for parsing the code coverage: https://www.npmjs.com/package/istanbul-lib-coverage https://github.com/istanbuljs/istanbuljs/tree/master/packages/istanbul-lib-coverage

Motivation

Per test code coverage is another requirement for intelligent test runner.

Plugin Checklist

• [x] Unit tests.
• [ ] TypeScript definitions.
• [ ] TypeScript tests.
• [ ] API documentation.
• [ ] CircleCI jobs/workflows.
• [ ] Plugin is exported.

Additional Notes

[github-actions[bot]]

Overall package size

Self size: 2.6 MB Deduped: 29.78 MB No deduping: 30.41 MB

Dependency sizes

name	version	self size	total size
@datadog/pprof	1.0.2	8.74 MB	14.46 MB
@datadog/native-metrics	1.4.2	6.61 MB	7.04 MB
@datadog/native-appsec	1.2.1	5.1 MB	5.43 MB
opentracing	0.14.7	194.81 kB	194.81 kB
@datadog/sketches-js	2.0.0	105.44 kB	105.44 kB
lodash.sortby	4.7.0	75.76 kB	75.76 kB
semver	5.7.1	61.58 kB	61.58 kB
ignore	5.2.0	48.87 kB	48.87 kB
import-in-the-middle	1.3.0	30.3 kB	34.77 kB
istanbul-lib-coverage	3.2.0	29.34 kB	29.34 kB
retry	0.10.1	27.44 kB	27.44 kB
lodash.uniq	4.5.0	25.01 kB	25.01 kB
limiter	1.1.5	23.17 kB	23.17 kB
lodash.kebabcase	4.1.1	17.75 kB	17.75 kB
lodash.pick	4.4.0	16.33 kB	16.33 kB
crypto-randomuuid	1.0.0	11.18 kB	11.18 kB
diagnostics_channel	1.1.0	7.07 kB	7.07 kB
path-to-regexp	0.1.7	6.78 kB	6.78 kB
koalas	1.0.2	6.47 kB	6.47 kB
methods	1.1.2	5.29 kB	5.29 kB
module-details-from-path	1.0.3	4.47 kB	4.47 kB

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[codecov[bot]]

Codecov Report

Merging #2271 (2406421) into master (995da60) will decrease coverage by 0.29%. The diff coverage is 89.86%.

@@            Coverage Diff             @@
##           master    #2271      +/-   ##
==========================================
- Coverage   92.86%   92.57%   -0.30%     
==========================================
  Files         222      224       +2     
  Lines        8547     8655     +108     
==========================================
+ Hits         7937     8012      +75     
- Misses        610      643      +33     

Impacted Files	Coverage Δ
...ges/dd-trace/src/encode/agentless-ci-visibility.js	64.67% <ø> (-1.81%)	:arrow_down:
...ace/src/ci-visibility/exporters/agentless/index.js	80.95% <70.37%> (-19.05%)	:arrow_down:
...ce/src/ci-visibility/exporters/agentless/writer.js	91.30% <75.00%> (-8.70%)	:arrow_down:
packages/dd-trace/src/exporters/common/writer.js	78.94% <75.00%> (ø)
packages/datadog-instrumentations/src/jest.js	82.82% <85.71%> (-16.00%)	:arrow_down:
...-visibility/exporters/agentless/coverage-writer.js	90.90% <90.90%> (ø)
packages/datadog-plugin-jest/src/index.js	83.33% <100.00%> (-9.69%)	:arrow_down:
packages/dd-trace/src/config.js	98.96% <100.00%> (+0.02%)	:arrow_up:
packages/dd-trace/src/encode/0.4.js	98.05% <100.00%> (-0.02%)	:arrow_down:
...ages/dd-trace/src/encode/coverage-ci-visibility.js	100.00% <100.00%> (ø)
... and 5 more

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[juan-fernandez]

any other concern @rochdev ? I think I applied all the feedback