test: enforce deps deduplication (#4097)

* build: use fewer babel versions

* build: dedup

* test: test deps dedups

* fix: test.yml

* fix: typo

* test: failing

* fix: dedup

* fix: dedup

* test: comment dedup tests

* chore: whitespace

.github/workflows/test.yml

@@ -18,6 +18,17 @@ jobs:
       - uses: ./.github/actions/setup
       - run: yarn lint
   
+  deps-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./.github/actions/setup
+      # Test that deps satisfy both "fewer" and "highest" strategies. This is to ensure we are
+      # up-to-date ("highest") while avoiding increasing package size ("fewer").
+      # These are readonly (--list) and explicitly exclude packages which only satisfy one strategy.
+      - run: npx yarn-deduplicate --strategy=fewer --list --fail --exclude commander safe-buffer
+      - run: npx yarn-deduplicate --strategy=highest --list --fail --exclude commander safe-buffer
+
   unit-tests:
     runs-on: ubuntu-latest
     steps: