diff --git a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
index 9f54fe3ef..db5973ddd 100644
--- a/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
+++ b/qa/rolling-upgrade/src/test/java/org/opensearch/knn/bwc/AbstractRollingUpgradeTestCase.java
@@ -71,7 +71,10 @@ public static ClusterType instance(String value) {
     }
 
     protected final ClusterType getClusterType() {
-        return ClusterType.instance(System.getProperty(BWCSUITE_CLUSTER));
+        if (System.getProperty(BWCSUITE_CLUSTER) != null) {
+            return ClusterType.instance(System.getProperty(BWCSUITE_CLUSTER));
+        }
+        throw new IllegalArgumentException(String.format("[%s] value is null", BWCSUITE_CLUSTER));
     }
 
     protected final boolean isFirstMixedRound() {
diff --git a/src/main/java/org/opensearch/knn/indices/ModelDao.java b/src/main/java/org/opensearch/knn/indices/ModelDao.java
index 1d88c9a00..c1440f856 100644
--- a/src/main/java/org/opensearch/knn/indices/ModelDao.java
+++ b/src/main/java/org/opensearch/knn/indices/ModelDao.java
@@ -466,7 +466,13 @@ public ModelMetadata getMetadata(String modelId) {
         }
 
         private String getMapping() throws IOException {
-            URL url = ModelDao.class.getClassLoader().getResource(MODEL_INDEX_MAPPING_PATH);
+            URL url = null;
+            if (ModelDao.class.getClassLoader() != null) {
+                url = ModelDao.class.getClassLoader().getResource(MODEL_INDEX_MAPPING_PATH);
+            } else {
+                throw new IllegalArgumentException("ClassLoader of ModelDao Class is null");
+            }
+
             if (url == null) {
                 throw new IllegalStateException("Unable to retrieve mapping for \"" + MODEL_INDEX_NAME + "\"");
             }
diff --git a/src/test/java/org/opensearch/knn/index/FaissIT.java b/src/test/java/org/opensearch/knn/index/FaissIT.java
index 9da067fde..44c6f41d4 100644
--- a/src/test/java/org/opensearch/knn/index/FaissIT.java
+++ b/src/test/java/org/opensearch/knn/index/FaissIT.java
@@ -66,11 +66,15 @@ public class FaissIT extends KNNRestTestCase {
 
     @BeforeClass
     public static void setUpClass() throws IOException {
-        URL testIndexVectors = FaissIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
-        URL testQueries = FaissIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
-        assert testIndexVectors != null;
-        assert testQueries != null;
-        testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        if (FaissIT.class.getClassLoader() != null) {
+            URL testIndexVectors = FaissIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
+            URL testQueries = FaissIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
+            assert testIndexVectors != null;
+            assert testQueries != null;
+            testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        } else {
+            throw new IllegalArgumentException("ClassLoader of FaissIT Class is null");
+        }
     }
 
     @SneakyThrows
diff --git a/src/test/java/org/opensearch/knn/index/NmslibIT.java b/src/test/java/org/opensearch/knn/index/NmslibIT.java
index 87bbe588f..504db33a2 100644
--- a/src/test/java/org/opensearch/knn/index/NmslibIT.java
+++ b/src/test/java/org/opensearch/knn/index/NmslibIT.java
@@ -44,11 +44,15 @@ public class NmslibIT extends KNNRestTestCase {
 
     @BeforeClass
     public static void setUpClass() throws IOException {
-        URL testIndexVectors = FaissIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
-        URL testQueries = FaissIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
-        assert testIndexVectors != null;
-        assert testQueries != null;
-        testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        if (NmslibIT.class.getClassLoader() != null) {
+            URL testIndexVectors = NmslibIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
+            URL testQueries = NmslibIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
+            assert testIndexVectors != null;
+            assert testQueries != null;
+            testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        } else {
+            throw new IllegalArgumentException("ClassLoader of NmslibIT Class is null");
+        }
     }
 
     public void testEndToEnd() throws Exception {
diff --git a/src/test/java/org/opensearch/knn/index/OpenSearchIT.java b/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
index 4130e2df5..4f4d50208 100644
--- a/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
+++ b/src/test/java/org/opensearch/knn/index/OpenSearchIT.java
@@ -47,11 +47,15 @@ public class OpenSearchIT extends KNNRestTestCase {
 
     @BeforeClass
     public static void setUpClass() throws IOException {
-        URL testIndexVectors = FaissIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
-        URL testQueries = FaissIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
-        assert testIndexVectors != null;
-        assert testQueries != null;
-        testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        if (OpenSearchIT.class.getClassLoader() != null) {
+            URL testIndexVectors = OpenSearchIT.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
+            URL testQueries = OpenSearchIT.class.getClassLoader().getResource("data/test_queries_100x128.csv");
+            assert testIndexVectors != null;
+            assert testQueries != null;
+            testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+        } else {
+            throw new IllegalArgumentException("ClassLoader of OpenSearchIT Class is null");
+        }
     }
 
     public void testEndToEnd() throws Exception {
diff --git a/src/test/java/org/opensearch/knn/jni/JNIServiceTests.java b/src/test/java/org/opensearch/knn/jni/JNIServiceTests.java
index 8e3382ece..80aece58e 100644
--- a/src/test/java/org/opensearch/knn/jni/JNIServiceTests.java
+++ b/src/test/java/org/opensearch/knn/jni/JNIServiceTests.java
@@ -65,14 +65,18 @@ public class JNIServiceTests extends KNNTestCase {
 
     @BeforeClass
     public static void setUpClass() throws IOException {
-        URL testIndexVectors = JNIServiceTests.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
-        URL testIndexVectorsNested = JNIServiceTests.class.getClassLoader().getResource("data/test_vectors_nested_1000x128.json");
-        URL testQueries = JNIServiceTests.class.getClassLoader().getResource("data/test_queries_100x128.csv");
-        assert testIndexVectors != null;
-        assert testIndexVectorsNested != null;
-        assert testQueries != null;
-        testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
-        testDataNested = new TestUtils.TestData(testIndexVectorsNested.getPath(), testQueries.getPath());
+        if (JNIServiceTests.class.getClassLoader() != null) {
+            URL testIndexVectors = JNIServiceTests.class.getClassLoader().getResource("data/test_vectors_1000x128.json");
+            URL testIndexVectorsNested = JNIServiceTests.class.getClassLoader().getResource("data/test_vectors_nested_1000x128.json");
+            URL testQueries = JNIServiceTests.class.getClassLoader().getResource("data/test_queries_100x128.csv");
+            assert testIndexVectors != null;
+            assert testIndexVectorsNested != null;
+            assert testQueries != null;
+            testData = new TestUtils.TestData(testIndexVectors.getPath(), testQueries.getPath());
+            testDataNested = new TestUtils.TestData(testIndexVectorsNested.getPath(), testQueries.getPath());
+        } else {
+            throw new IllegalArgumentException("ClassLoader of JNIServiceTests Class is null");
+        }
     }
 
     public void testCreateIndex_invalid_engineNotSupported() {
diff --git a/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java b/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
index 1d984927f..eb01d3d92 100644
--- a/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
+++ b/src/testFixtures/java/org/opensearch/knn/KNNRestTestCase.java
@@ -121,19 +121,24 @@ public static void dumpCoverage() throws IOException, MalformedObjectNameExcepti
         }
 
         String serverUrl = System.getProperty("jmx.serviceUrl");
-        try (JMXConnector connector = JMXConnectorFactory.connect(new JMXServiceURL(serverUrl))) {
-            IProxy proxy = MBeanServerInvocationHandler.newProxyInstance(
-                connector.getMBeanServerConnection(),
-                new ObjectName("org.jacoco:type=Runtime"),
-                IProxy.class,
-                false
-            );
-
-            Path path = Path.of(jacocoBuildPath, "integTest.exec");
-            Files.write(path, proxy.getExecutionData(false));
-        } catch (Exception ex) {
-            log.error("Failed to dump coverage: ", ex);
-            throw new RuntimeException("Failed to dump coverage: " + ex);
+        if (serverUrl != null) {
+            try (JMXConnector connector = JMXConnectorFactory.connect(new JMXServiceURL(serverUrl))) {
+                IProxy proxy = MBeanServerInvocationHandler.newProxyInstance(
+                    connector.getMBeanServerConnection(),
+                    new ObjectName("org.jacoco:type=Runtime"),
+                    IProxy.class,
+                    false
+                );
+
+                Path path = Path.of(Path.of(jacocoBuildPath, "integTest.exec").toFile().getCanonicalPath());
+                Files.write(path, proxy.getExecutionData(false));
+            } catch (Exception ex) {
+                log.error("Failed to dump coverage: ", ex);
+                throw new RuntimeException("Failed to dump coverage: " + ex);
+            }
+        } else {
+            log.error("Failed to dump coverage because JMX Service URL is null");
+            throw new IllegalArgumentException("JMX Service URL is null");
         }
     }