Added NPM scripts for running specific tests.

package.json

@@ -10,6 +10,8 @@
     "postinstall": "run-s postinstall:**",
     "lint:app": "cd syntactic-monoids && npm run lint",
     "lint": "run-s --continue-on-error lint:**",
+    "test-once:comments": "cd syntactic-monoids && npm run test-once:comments",
+    "test-once:texMath": "cd syntactic-monoids && npm run test-once:texMath",
     "test-once": "cd syntactic-monoids && npm run test-once",
     "test": "run-s test-once"
   },

syntactic-monoids/package.json

@@ -8,6 +8,8 @@
   "scripts": {
     "lint:js": "eslint --max-warnings 0 ./src",
     "lint": "run-s --continue-on-error lint:**",
+    "test-once:comments": "node --experimental-vm-modules node_modules/jest/bin/jest.js -t \"the JavaScript comments monoid\"",
+    "test-once:texMath": "node --experimental-vm-modules node_modules/jest/bin/jest.js -t \"the TeX math monoid\"",
     "test-once": "node --experimental-vm-modules node_modules/jest/bin/jest.js --coverage",
     "test": "node --experimental-vm-modules node_modules/jest/bin/jest.js --watchAll --coverage"
   },