Add a way to measure test coverage (#777)

* Add a way to measure test coverage

* Drop an accidentally added dependency

* Changelog

.gitignore

@@ -21,6 +21,7 @@ lib-cov
 
 # Coverage directory used by tools like istanbul
 coverage
+.nyc_output
 
 # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
 .grunt

changelog.d/777.misc

@@ -0,0 +1 @@
+Add a way to measure test coverage.

package.json

@@ -13,6 +13,7 @@
     "build:app": "tsc --build",
     "build:widget": "vite build --config widget/vite.config.ts",
     "test": "yarn test:unit && yarn test:integration",
+    "test:coverage": "nyc --reporter=text --reporter=html mocha --exit --reporter list --ui bdd --require ts-node/register --recursive tests/*/*.ts",
     "test:unit": "mocha --require ts-node/register --recursive tests/unit/*.ts",
     "test:integration": "mocha --exit --reporter list --ui bdd --require ts-node/register --recursive tests/integration/*.ts",
     "test:postgres": "SLACKBRIDGE_TEST_ENABLEPG=yes mocha --reporter list --ui bdd --require ts-node/register --recursive tests/integration/PgDatastoreTest.ts",
@@ -85,6 +86,7 @@
     "eslint-plugin-react-hooks": "^4.6.0",
     "js-yaml": "^4.1.0",
     "mocha": "^10.0.0",
+    "nyc": "^15.1.0",
     "postcss": "^8.4.21",
     "prom-client": "^14.0.1",
     "source-map-support": "^0.5.19",