Test: Allow FakeAgent to respond to remote config requests

[watson]

Allow integration tests to mock the remote config abilities of the agent.

This is done by first setting up a new remote config "file" using the new FakeAgent#addRemoteConfig method before running the main part of the integration test. This primes the fake agent to respond with this config for http requests to the /v0.7/config endpoint.

Note to reviewers

This ability is needed by the integration tests in an upcoming Dynamic Instrumentation PR. I've separated it into its own PR to make the review easier.

I have not updated any of the existing tests to make uses of this ability. So this new ability of the FakeAgent class isn't actually used by any of our existing code in this PR. Let me know if there's an obvious place where we could make use of this so that I can update the PR to do so.

To make the review process easier, I've split this PR into two commits:

1. 73cf5d765948f368857a7a50448555bfb160b614: This commit contains the actual code changes and is a good starting point for easier diffing.
2. bc05f98d46c8634ae4c42cc16771533114cdd505: This commit contains only some refactoring to move code around to easier maintenance.

Usage example

Here's an example of how we'd use the new FakeAgent#addRemoteConfig method to register a Remote Config file for use in Dynamic Instrumentation:

agent.addRemoteConfig({
  product: 'LIVE_DEBUGGING',
  id: 'foobar',
  config: {
    id: 'foobar,
    version: 0,
    type: 'LOG_PROBE',
    language: 'javascript',
    where: { sourceFile: 'index.js', lines: ['15'] },
    tags: [],
    template: 'Hello World!',
    segments: [{ str: 'Hello World!' }],
    captureSnapshot: false,
    capture: { maxReferenceDepth: 3 },
    sampling: { snapshotsPerSecond: 5000 },
    evaluateAt: 'EXIT'
  }
})

[github-actions]

Overall package size

Self size: 6.99 MB
Deduped: 58.21 MB
No deduping: 58.49 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/native-appsec | 8.0.1 | 15.59 MB | 15.6 MB | | @datadog/native-iast-taint-tracking | 3.1.0 | 12.27 MB | 12.28 MB | | @datadog/pprof | 5.3.0 | 9.85 MB | 10.22 MB | | protobufjs | 7.2.5 | 2.77 MB | 5.16 MB | | @datadog/native-iast-rewriter | 2.4.1 | 2.14 MB | 2.23 MB | | @opentelemetry/core | 1.14.0 | 872.87 kB | 1.47 MB | | @datadog/native-metrics | 2.0.0 | 898.77 kB | 1.3 MB | | @opentelemetry/api | 1.8.0 | 1.21 MB | 1.21 MB | | import-in-the-middle | 1.8.1 | 71.67 kB | 785.15 kB | | msgpack-lite | 0.1.26 | 201.16 kB | 281.59 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | pprof-format | 2.1.0 | 111.69 kB | 111.69 kB | | @datadog/sketches-js | 2.1.0 | 109.9 kB | 109.9 kB | | semver | 7.6.3 | 95.82 kB | 95.82 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | lru-cache | 7.14.0 | 74.95 kB | 74.95 kB | | ignore | 5.3.1 | 51.46 kB | 51.46 kB | | int64-buffer | 0.1.10 | 49.18 kB | 49.18 kB | | shell-quote | 1.8.1 | 44.96 kB | 44.96 kB | | istanbul-lib-coverage | 3.2.0 | 29.34 kB | 29.34 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | dc-polyfill | 0.1.4 | 23.1 kB | 23.1 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | path-to-regexp | 0.1.7 | 6.78 kB | 6.78 kB | | koalas | 1.0.2 | 6.47 kB | 6.47 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]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.65%. Comparing base (ba0442f) to head (f9cdc04).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4626       +/-   ##
===========================================
+ Coverage   68.65%   90.65%   +22.00%     
===========================================
  Files         252      123      -129     
  Lines       11047     4420     -6627     
  Branches       33       33               
===========================================
- Hits         7584     4007     -3577     
+ Misses       3463      413     -3050     

☔ View full report in Codecov by Sentry.
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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-28 14:22:40

Comparing candidate commit 9fe4ffb in PR branch watson/DEBUG-2532/fake-agent with baseline commit ba0442f in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 260 metrics, 6 unstable metrics.

[watson]

• [DI] Add ability to take state snapshot #4549
• Prepare support for Dynamic Instrumentation #4492
• Test: Allow FakeAgent to respond to remote config requests #4626 👈
• master

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[simon-id]

I see there is no mention of RC capabilities. The client.capabilities field is a bitflag number encoded in base64 where each bit tells the backend that this client supports a specific feature. It's not technically required for the RC client to work, but we assume that the backend will send only what we support. I guess we can just assume the tests won't ever send data that we don't support 👍

[watson]

I guess we can just assume the tests won't ever send data that we don't support 👍

That was my idea, which is why I didn't bother validating the capabilities bitfield 🤷

[bengl]

Just the file name change, that's all.

[watson]

FYI, you can see this new capability of the FakeAgent in use in this upcoming PR: #4492 (look for the file integration-tests/debugger/index.spec.js)

[simon-id]

I would say let's remove all the superfluous fields. RC is complicated enough as it is haha. Let's keep the futurproofing for the futur, and focus on what we need to work first.
Lots of coments here sorry!

[watson]

FYI, I've updated the #4492 PR with usage of FakeAgent#updateRemoveConfig and FakeAgent#removeRemoveConfig (look for the file integration-tests/debugger/index.spec.js)