Add root-level GitHub Actions CI/CD pipeline for PR validation

.github/workflows/ci.yml

@@ -0,0 +1,73 @@
+name: CI
+
+on:
+  pull_request:
+    branches: ["main", "master"]
+  push:
+    branches: ["main", "master"]
+
+permissions:
+  contents: read
+
+jobs:
+  backend:
+    name: Backend – Build & Test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+
+      - name: Cache Gradle packages
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ hashFiles('backend/**/*.gradle*', 'backend/**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
+      - name: Make Gradle wrapper executable
+        run: chmod +x backend/gradlew
+
+      - name: Run Spotless check
+        working-directory: backend
+        run: ./gradlew spotlessCheck --no-daemon
+
+      - name: Build (with tests)
+        working-directory: backend
+        run: ./gradlew build --no-daemon
+
+  frontend:
+    name: Frontend – Lint & Build
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install dependencies
+        working-directory: frontend
+        run: npm ci
+
+      - name: Lint
+        working-directory: frontend
+        run: npm run lint
+
+      - name: Build
+        working-directory: frontend
+        run: npm run build

backend/src/main/java/com/wikipediafinder/backend/controller/MyController.java

@@ -36,8 +36,7 @@ public ResponseEntity<String> hello() {
   public ResponseEntity<Object> getResults(
       @RequestParam String startinglink, @RequestParam String endinglink) {
     try {
-      BFSResult result =
-          bfs.getPathWithStats(new PageNode(startinglink), new PageNode(endinglink));
+      BFSResult result = bfs.getPathWithStats(new PageNode(startinglink), new PageNode(endinglink));
 
       if (result.getPath() == null) {
         return new ResponseEntity<>(

backend/src/test/java/com/wikipediafinder/backend/controller/MyControllerTest.java

@@ -41,8 +41,7 @@ public void getResultsReturnsPathWhenFound() throws Exception {
     when(bfs.getPathWithStats(any(PageNode.class), any(PageNode.class)))
         .thenReturn(
             new BFSResult(
-                Arrays.asList(
-                    "https://en.wikipedia.org/wiki/A", "https://en.wikipedia.org/wiki/B"),
+                Arrays.asList("https://en.wikipedia.org/wiki/A", "https://en.wikipedia.org/wiki/B"),
                 2));
 
     mockMvc