NIAD-3349: Add CheckStyle to GitHub Actions

.github/workflows/test.yml

@@ -3,8 +3,45 @@ on:
   workflow_call:
 
 jobs:
+  checkstyle:
+    name: Checkstyle
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Setup Java 21 LTS
+        uses: actions/setup-java@v4
+        with:
+          java-version: 21
+          distribution: 'temurin'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      - name: Checkstyle
+        run: ./gradlew checkStyleMain checkstyleTest checkstyleIntTest
+
+      - name: Collect Artifacts
+        if: always()
+        run: |
+          mkdir -p artifacts
+          cp -r ./build/reports ./artifacts
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: 'Checkstyle Reports'
+          path: ./artifacts/**
+          compression-level: 9
+
+      - name: Temporary Artifacts Cleanup
+        run: rm -rf ./artifacts
+
   unit-tests:
     name: Unit Tests
+    needs: [ checkstyle ]
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repository
@@ -44,6 +81,7 @@ jobs:
 
   component-tests:
     name: Component Tests
+    needs: [ checkstyle ]
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repository
@@ -83,6 +121,7 @@ jobs:
 
   integration_tests:
     name: Integration Tests
+    needs: [ checkstyle ]
     permissions:
       contents: read
     runs-on: ubuntu-latest

src/test/java/uk/nhs/digital/nhsconnect/nhais/utils/PemFormatterTest.java

@@ -9,17 +9,16 @@ public class PemFormatterTest {
     @Test
     public void When_CertHasExtraWhitespace_Expect_ItIsTrimmed() {
 
-        // this warning is suppressed as the extra whitespace (including trailing whitespace) is intentional
-        @SuppressWarnings("com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSingleLineCheck")
+        //The extra whitespace (including trailing whitespace) is intentional for this test and has been suppressed with `\s`
         final String withWhitespace = """
              -----BEGIN CERTIFICATE-----
-                MIIFXzCCA0egAwIBAgIJALRbCSor9bEbMA0GCSqGSIb3DQEBCwUAMEUxCzAJBgNV 
-                
-                
+                MIIFXzCCA0egAwIBAgIJALRbCSor9bEbMA0GCSqGSIb3DQEBCwUAMEUxCzAJBgNV \s
+               \s
+               \s
                 W/JNIRmhLoeFNGNh8HvhI2PwOCsFiqT1rrCaUtusTyH0Ggs=
-            
-               -----END CERTIFICATE-----    
-            """;
+           \s
+               -----END CERTIFICATE-----   \s
+           \s""";
 
         final String trimmed = """
         -----BEGIN CERTIFICATE-----