Add test script to package.json

---

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.github/workflows/checks.yml

@@ -1,4 +1,4 @@
-name: Check chagnes
+name: Check changes
 
 on: [pull_request]
 
@@ -11,4 +11,5 @@ jobs:
         with:
           node-version: "12.x"
       - run: npm ci
-      - run: npm run lint
+      - run: npm run lint
+      - run: npm test

package.json

@@ -4,8 +4,8 @@
   "description": "Semantic Versioning Specification",
   "main": "semver.md",
   "scripts": {
-    "lint": "remark -qf semver.md",
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "lint": "remark -qf .",
+    "test": "remark -qf semver.md"
   },
   "repository": {
     "type": "git",