Add TypeScript declarations test

.github/workflows/ci.yml

@@ -33,6 +33,9 @@ jobs:
       - name: npm Check
         run: npm run check
 
+      - name: npm ts tests
+        run: npm run test-ts-decls
+
       - name: npm Test
         run: npm run test
 

CONTRIBUTORS-GUIDE.md

@@ -32,6 +32,8 @@ The project includes unit as well as integration tests for browser environments.
 
 All tests can be run at once with the command `npm run test`.
 
+If you've updated the TypeScript declaration files (`/types`), you should add some lines verifying the updates in `/ts-tests/index.ts` and then run the TypeScript compilation test using the `npm run test-ts-decls` command.
+
 For additional testing scripts or to get more insight on how these work, please refer to our [package.json](package.json) file.
 
 ### Linting and other useful checks

package.json

@@ -22,6 +22,7 @@
     "build": "npm run build:cjs && npm run build:esm",
     "build:esm": "rimraf esm && tsc -m es2015 --outDir esm",
     "build:cjs": "rimraf cjs && tsc -m CommonJS --outDir cjs",
+    "test-ts-decls": "tsc --build ts-tests",
     "test": "jest",
     "test:coverage": "jest --coverage",
     "all": "npm run check && npm run build && npm run test",