ExceptionUtil.lookupExceptionInCause refactored from recursion to a loop. Tests added

common/util/src/main/java/org/thingsboard/common/util/ExceptionUtil.java

@@ -38,15 +38,15 @@ public class ExceptionUtil {
     }
 
     public static Exception lookupExceptionInCause(Throwable source, Class<? extends Exception>... clazzes) {
-        if (source == null) {
+        while (source != null) {
-            return null;
+            for (Class<? extends Exception> clazz : clazzes) {
-        }
+                if (clazz.isAssignableFrom(source.getClass())) {
-        for (Class<?> clazz : clazzes) {
+                    return (Exception) source;
-            if (clazz.isAssignableFrom(source.getClass())) {
+                }
-                return (Exception) source;
             }
+            source = source.getCause();
         }
-        return lookupExceptionInCause(source.getCause(), clazzes);
+        return null;
     }
 
     public static String toString(Exception e, EntityId componentId, boolean stackTraceEnabled) {

common/util/src/test/java/org/thingsboard/common/util/ExceptionUtilTest.java

@@ -0,0 +1,74 @@
+/**
+ * Copyright © 2016-2023 The Thingsboard Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.thingsboard.common.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ExceptionUtilTest {
+
+    final Exception cause = new RuntimeException();
+
+    @Test
+    void givenRootCause_whenLookupExceptionInCause_thenReturnRootCauseAndNoStackOverflow() {
+        Exception e = cause;
+        for (int i = 0; i <= 16384; i++) {
+            e = new Exception(e);
+        }
+        assertThat(ExceptionUtil.lookupExceptionInCause(e, RuntimeException.class)).isSameAs(cause);
+    }
+
+    @Test
+    void givenCause_whenLookupExceptionInCause_thenReturnCause() {
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(cause), RuntimeException.class)).isSameAs(cause);
+    }
+
+    @Test
+    void givenNoCauseAndExceptionIsWantedCauseClass_whenLookupExceptionInCause_thenReturnSelf() {
+        assertThat(ExceptionUtil.lookupExceptionInCause(cause, RuntimeException.class)).isSameAs(cause);
+    }
+
+    @Test
+    void givenNoCause_whenLookupExceptionInCause_thenReturnNull() {
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(), RuntimeException.class)).isNull();
+    }
+
+    @Test
+    void givenNotWantedCause_whenLookupExceptionInCause_thenReturnNull() {
+        final Exception cause = new IOException();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(cause), RuntimeException.class)).isNull();
+    }
+
+    @Test
+    void givenCause_whenLookupExceptionInCauseByMany_thenReturnFirstCause() {
+        final Exception causeIAE = new IllegalAccessException();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIAE))).isNull();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIAE), IOException.class, NoSuchFieldException.class)).isNull();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIAE), IllegalAccessException.class, IOException.class, NoSuchFieldException.class)).isSameAs(causeIAE);
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIAE), IOException.class, NoSuchFieldException.class, IllegalAccessException.class)).isSameAs(causeIAE);
+
+        final Exception causeIOE = new IOException(causeIAE);
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIOE))).isNull();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIAE), ClassNotFoundException.class, NoSuchFieldException.class)).isNull();
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIOE), IOException.class, NoSuchFieldException.class)).isSameAs(causeIOE);
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIOE), IllegalAccessException.class, IOException.class, NoSuchFieldException.class)).isSameAs(causeIOE);
+        assertThat(ExceptionUtil.lookupExceptionInCause(new Exception(causeIOE), IOException.class, NoSuchFieldException.class, IllegalAccessException.class)).isSameAs(causeIOE);
+    }
+
+}