Add test watch script (#3551)

Refines #3548.

See #3548 (comment)

Author: yaacovCR

Diff for: .github/workflows/ci.yml

@@ -142,8 +142,8 @@ jobs:
       - name: Install Dependencies
         run: npm ci --ignore-scripts
 
-      - name: Run Tests
-        run: npm run testonly
+      - name: Run Tests with coverage
+        run: npm run testonly:cover
 
   build-npm-dist:
     name: Build 'npmDist' artifact

Diff for: package.json

@@ -33,10 +33,12 @@
     "fuzzonly": "mocha --full-trace src/**/__tests__/**/*-fuzz.ts",
     "changelog": "node resources/gen-changelog.js",
     "benchmark": "node benchmark/benchmark.js",
-    "test": "npm run lint && npm run check && npm run testonly && npm run prettier:check && npm run check:spelling && npm run check:integrations",
+    "test": "npm run lint && npm run check && npm run testonly:cover && npm run prettier:check && npm run check:spelling && npm run check:integrations",
     "lint": "eslint --cache --max-warnings 0 .",
     "check": "tsc --pretty",
-    "testonly": "c8 mocha --full-trace src/**/__tests__/**/*-test.ts",
+    "testonly": "mocha --full-trace src/**/__tests__/**/*-test.ts",
+    "testonly:cover": "c8 npm run testonly",
+    "testonly:watch": "npm run testonly -- --watch",
     "prettier": "prettier --write --list-different .",
     "prettier:check": "prettier --check .",
     "check:spelling": "cspell --cache --no-progress '**/*'",