fix(jest): reduce memory usage (mdn#8753)

* fix(jest): reduce memory usage

By combining `node --expose-gc` with `jest --logHeapUsage`.

* fix(jest): isolate modules with ts-jest

* ci(pr-kumascript): run if {jest.config,package}.json change

.github/workflows/pr-kumascript.yml

@@ -14,6 +14,8 @@ on:
     paths:
       - kumascript/**
       - .github/workflows/pr-kumascript.yml
+      - jest.config.json
+      - package.json
       - yarn.lock
 
 jobs:

jest.config.json

@@ -10,6 +10,7 @@
       "ts-jest",
       {
         "babelConfig": true,
+        "isolatedModules": true,
         "useESM": true
       }
     ]

package.json

@@ -29,7 +29,7 @@
     "filecheck": "ts-node filecheck/cli.ts",
     "install:all": "find . -mindepth 2 -name 'yarn.lock' ! -wholename '**/node_modules/**' -print0 | xargs -n1 -0 sh -cx 'yarn --cwd $(dirname $0) install'",
     "install:all:npm": "find . -mindepth 2 -name 'package-lock.json' ! -wholename '**/node_modules/**' -print0 | xargs -n1 -0 sh -cx 'npm --prefix $(dirname $0) install'",
-    "jest": "cross-env NODE_OPTIONS=--experimental-vm-modules jest",
+    "jest": "node --experimental-vm-modules --expose-gc ./node_modules/.bin/jest --logHeapUsage",
     "m2h": "ts-node markdown/m2h/cli.ts",
     "prepack": "yarn build:dist",
     "prepare": "husky install && yarn install:all && yarn install:all:npm",