cd: Error if html in file

Jenkinsfile

@@ -2,9 +2,27 @@ pipeline {
     agent any
 
     stages {
-        stage('None') {
+        stage('Test Files') {
             steps {
-                echo "Done"
+                // Search for occurrences of "<filename>.html"
+                script {
+                    def fileExists = false
+
+                    // Find files with "<filename>.html" occurrences
+                    def affectedFiles = sh returnStdout: true, script: 'grep -rl ".html" ./*.html'
+                    // Trim
+                    affectedFiles = affectedFiles.trim()
+
+                    // If affectedFiles is not empty, set fileExists to true
+                    if (affectedFiles) {
+                        fileExists = true
+                    }
+
+                    // Fail the build and display the affected files
+                    if (fileExists) {
+                        error("Error: Found occurrences of 'filename.html' in the following files:\n${affectedFiles}")
+                    }
+                }
             }
         }
     }