chore(rollup-plugin): speed up and reduce memory usage in tests

[cardoso]

Details

This PR makes a few tweaks to tests in @lwc/rollup-plugin.

It improve overall execution time from ~3.78s to ~1.44s (-62%) in my local environment.

It also reduces memory usage significantly in some tests.

This makes development while running tests in watch mode a bit more pleasant.

Before

 ✓ resolver  (13 tests) 2843ms 530 MB heap used
 ✓ compilerConfig  (6 tests) 1920ms 102 MB heap used
 ✓ apiVersion  (5 tests) 1669ms 261 MB heap used
 ✓ enableStaticContentOptimization  (4 tests) 1266ms 205 MB heap used
 ✓ warnings  (1 test) 497ms 97 MB heap used
 ✓ integrations  (1 test) 466ms 98 MB heap used
 ✓ rootDir  (2 tests) 19ms 34 MB heap used

 Test Files  7 passed (7)
      Tests  32 passed (32)
   Start at  05:29:27
   Duration  3.78s (transform 422ms, setup 0ms, collect 4.45s, tests 8.68s, environment 1ms, prepare 399ms)

After

 ✓ resolver  (13 tests) 190ms 50 MB heap used
 ✓ compilerConfig  (6 tests) 164ms 51 MB heap used
 ✓ apiVersion  (5 tests) 64ms 35 MB heap used
 ✓ enableStaticContentOptimization  (4 tests) 64ms 40 MB heap used
 ✓ warnings  (1 test) 49ms 36 MB heap used
 ✓ integrations  (1 test) 39ms 35 MB heap used
 ✓ rootDir  (2 tests) 20ms 37 MB heap used

 Test Files  7 passed (7)
      Tests  32 passed (32)
   Start at  05:26:25
   Duration  1.44s (transform 413ms, setup 0ms, collect 4.19s, tests 590ms, environment 1ms, prepare 362ms)

Does this pull request introduce a breaking change?

• 😮‍💨 No, it does not introduce a breaking change.

Does this pull request introduce an observable change?

• 🤞 No, it does not introduce an observable change.

GUS work item

[nolanlawson]

Nice, so the main improvement here is external: ['lwc'] which means we don't test Rollup's ability to bundle lwc itself (probably useless to test...)

LGTM, thank you!

[nolanlawson]

/nucleus test