Docgen: replace assertions for getIntermediateRepresentation unit tests with snapshots

[ciampo]

Description

Replace all the assertions in the getIntermediateRepresentation unit tests with equivalent snapshot checks.

This approach requires less developer maintenance while serving the same purpose as the previous hand-written assertions.

How has this been tested?

• Run npm run test-unit packages/docgen
• Make sure that all tests are passing

Screenshots

N/A

Types of changes

Refactor

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• (N/A) I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[tyxla]

Looks good and tests pass 👍

I might be missing some context or rationale, but I'd love to get a second opinion on whether this is a good (and common in Gutenberg) use case for inline snapshot testing. FWIW I can definitely see value in it and how it reduces the manual part of maintaining these tests, which is why I am inclined to agree to move forward here.

[ciampo]

I'd love to get a second opinion on whether this is a good (and common in Gutenberg) use case for inline snapshot testing

Absolutely. In fact, we discussed also measuring the time that those tests take before and after this PR — I am planning on posting that data later today

[ciampo]

I did a little experiment to understand if there's a difference in execution speed when using inline snapshots.

• I pulled the latest changes on trunk and rebased this PR's branch on top of it
• I ran the npm run test-unit packages/docgen command for 5 times on both branches

Results

• Average execution time on trunk: 3.5578s
• Average execution time on this PR: 3.1494s

Although this is by no means a comprehensive analysis, these first results seem to show that there isn't a loss in performance when running tests with inline snapshots.

View details

On trunk (no snapshots):

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   0 total
Time:        4.749 s
Ran all test suites matching /packages\/docgen/i.

--- 

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   0 total
Time:        3.399 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   0 total
Time:        4.033 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   0 total
Time:        2.818 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   0 total
Time:        2.79 s
Ran all test suites matching /packages\/docgen/i.

On this branch (with inline snapshots):

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   27 passed, 27 total
Time:        3.645 s
Ran all test suites matching /packages\/docgen/i.

--- 

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   27 passed, 27 total
Time:        3.848 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   27 passed, 27 total
Time:        2.72 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   27 passed, 27 total
Time:        2.72 s
Ran all test suites matching /packages\/docgen/i.

---

Test Suites: 6 passed, 6 total
Tests:       107 passed, 107 total
Snapshots:   27 passed, 27 total
Time:        2.814 s
Ran all test suites matching /packages\/docgen/i.

[gziolo]

Nice, thank you for working on this PR 👍🏻