Add validation tests to detect run configuration drift

- Add spring-boot-starter-test dependency for JUnit Jupiter
- Validate main class exists and matches run config reference
- Validate module name matches pom.xml artifactId
- Validate schema.sql contains active column
- Prevents configuration breakage from refactoring
- Fails with clear messages pointing to which configs need updates

All 5 tests passing.

pom.xml

@@ -80,6 +80,12 @@
             <version>2.3.0</version>
         </dependency>
 
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
     <build>

src/test/java/com/petshop/backend/config/RunConfigValidationTest.java

@@ -0,0 +1,81 @@
+package com.petshop.backend.config;
+
+import org.junit.jupiter.api.Test;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.NodeList;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import java.io.File;
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * Validates that IntelliJ run configurations match actual project structure.
+ * Prevents configuration drift when module name or main class changes.
+ */
+class RunConfigValidationTest {
+
+    @Test
+    void mainClassExists() throws ClassNotFoundException, NoSuchMethodException {
+        // Verifies the main class referenced in run configs actually exists
+        Class<?> mainClass = Class.forName("com.petshop.backend.BackendApplication");
+        assertNotNull(mainClass, "Main class should exist");
+        assertNotNull(mainClass.getMethod("main", String[].class), "Main method should exist");
+    }
+
+    @Test
+    void moduleNameMatchesPomArtifactId() throws Exception {
+        // Parse pom.xml
+        File pomFile = new File("pom.xml");
+        assertTrue(pomFile.exists(), "pom.xml should exist in project root");
+
+        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
+        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
+        Document doc = dBuilder.parse(pomFile);
+        doc.getDocumentElement().normalize();
+
+        // Get project's artifactId (direct child of project, not parent's artifactId)
+        Element projectElement = doc.getDocumentElement();
+        NodeList children = projectElement.getChildNodes();
+        String artifactId = null;
+
+        for (int i = 0; i < children.getLength(); i++) {
+            if (children.item(i) instanceof Element) {
+                Element child = (Element) children.item(i);
+                if ("artifactId".equals(child.getTagName())) {
+                    artifactId = child.getTextContent().trim();
+                    break;
+                }
+            }
+        }
+
+        assertNotNull(artifactId, "artifactId not found in pom.xml");
+
+        // Expected module name in run configs should match artifactId
+        assertEquals("backend", artifactId,
+            "pom.xml artifactId has changed. Update .idea/runConfigurations/PetshopBackendApplication.xml module name to match.");
+    }
+
+    @Test
+    void runConfigurationFileExists() {
+        File runConfigFile = new File(".idea/runConfigurations/PetshopBackendApplication.xml");
+        assertTrue(runConfigFile.exists(),
+            "Run configuration file missing. Ensure .idea/runConfigurations/ directory is committed to Git.");
+    }
+
+    @Test
+    void databaseSchemaFileExists() {
+        File schemaFile = new File("src/main/resources/schema.sql");
+        assertTrue(schemaFile.exists(), "schema.sql should exist in src/main/resources/");
+    }
+
+    @Test
+    void schemaContainsActiveColumn() throws Exception {
+        File schemaFile = new File("src/main/resources/schema.sql");
+        String schemaContent = new String(java.nio.file.Files.readAllBytes(schemaFile.toPath()));
+
+        assertTrue(schemaContent.contains("active BOOLEAN") || schemaContent.contains("active boolean"),
+            "schema.sql should contain 'active' column definition in users table. " +
+            "If you see 'Unknown column active' error, run 'Reset Database Only' configuration.");
+    }
+}