chore(engine): avoid more potential NPE in ExceptionUtil (#3826)

* add ExceptionUtilTest

closes to #3887

engine/src/main/java/org/camunda/bpm/engine/impl/util/ExceptionUtil.java

@@ -144,13 +144,17 @@ public static SQLException unwrapException(ProcessEngineException genericPersist
 
   public static boolean checkValueTooLongException(SQLException sqlException) {
     String message = sqlException.getMessage();
+    if (message != null) {
+      message = message.toLowerCase();
+    } else {
+      return false;
+    }
     return message.contains("too long") ||
         message.contains("too large") ||
-        message.contains("TOO LARGE") ||
-        message.contains("ORA-01461") ||
-        message.contains("ORA-01401") ||
+        message.contains("ora-01461") ||
+        message.contains("ora-01401") ||
         message.contains("data would be truncated") ||
-        message.contains("SQLCODE=-302, SQLSTATE=22001");
+        message.contains("sqlcode=-302, sqlstate=22001");
   }
 
   public static boolean checkValueTooLongException(ProcessEngineException genericPersistenceException) {
@@ -171,11 +175,17 @@ public static boolean checkConstraintViolationException(ProcessEngineException g
     }
 
     String message = sqlException.getMessage();
+    if (message != null) {
+      message = message.toLowerCase();
+    } else {
+      return false;
+    }
+
     return message.contains("constraint") ||
         message.contains("violat") ||
-        message.toLowerCase().contains("duplicate") ||
-        message.contains("ORA-00001") ||
-        message.contains("SQLCODE=-803, SQLSTATE=23505");
+        message.contains("duplicate") ||
+        message.contains("ora-00001") ||
+        message.contains("sqlcode=-803, sqlstate=23505");
   }
 
   public static boolean checkForeignKeyConstraintViolation(PersistenceException persistenceException) {
@@ -189,7 +199,13 @@ public static boolean checkForeignKeyConstraintViolation(PersistenceException pe
   }
 
   public static boolean checkForeignKeyConstraintViolation(SQLException sqlException) {
-    String message = sqlException.getMessage().toLowerCase();
+    String message = sqlException.getMessage();
+    if (message != null) {
+      message = message.toLowerCase();
+    } else {
+      return false;
+    }
+
     String sqlState = sqlException.getSQLState();
     int errorCode = sqlException.getErrorCode();
 
@@ -218,7 +234,13 @@ public static boolean checkVariableIntegrityViolation(PersistenceException persi
       return false;
     }
 
-    String message = sqlException.getMessage().toLowerCase();
+    String message = sqlException.getMessage();
+    if (message != null) {
+      message = message.toLowerCase();
+    } else {
+      return false;
+    }
+
     String sqlState = sqlException.getSQLState();
     int errorCode = sqlException.getErrorCode();
 

engine/src/test/java/org/camunda/bpm/engine/impl/util/ExceptionUtilTest.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
+ * under one or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership. Camunda licenses this file to you under the Apache License,
+ * Version 2.0; 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.camunda.bpm.engine.impl.util;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+
+import java.sql.SQLException;
+import org.apache.ibatis.exceptions.PersistenceException;
+import org.camunda.bpm.engine.ProcessEngineException;
+import org.junit.Test;
+
+public class ExceptionUtilTest {
+
+  @Test
+  public void checkValueTooLongException() {
+    assertThat(ExceptionUtil.checkValueTooLongException(mock(SQLException.class))).isFalse();
+
+    SQLException tooLong = mock(SQLException.class);
+    doReturn("too long").when(tooLong).getMessage();
+    assertThat(ExceptionUtil.checkValueTooLongException(tooLong)).isTrue();
+  }
+
+  @Test
+  public void checkConstraintViolationException() {
+    assertThat(ExceptionUtil.checkConstraintViolationException(new ProcessEngineException(new PersistenceException(mock(SQLException.class))))).isFalse();
+
+    SQLException constraintViolation = mock(SQLException.class);
+    doReturn("ora-00001").when(constraintViolation).getMessage();
+    assertThat(ExceptionUtil.checkConstraintViolationException(new ProcessEngineException(new PersistenceException(constraintViolation)))).isTrue();
+  }
+
+  @Test
+  public void checkForeignKeyConstraintViolation() {
+    assertThat(ExceptionUtil.checkForeignKeyConstraintViolation(mock(SQLException.class))).isFalse();
+
+    SQLException constraintViolation = mock(SQLException.class);
+    doReturn("integrity constraint").when(constraintViolation).getMessage();
+    assertThat(ExceptionUtil.checkForeignKeyConstraintViolation(constraintViolation)).isTrue();
+  }
+
+  @Test
+  public void checkVariableIntegrityViolation() {
+    assertThat(ExceptionUtil.checkVariableIntegrityViolation(new PersistenceException(mock(SQLException.class)))).isFalse();
+
+    SQLException integrityViolation = mock(SQLException.class);
+    doReturn("act_uniq_variable").when(integrityViolation).getMessage();
+    doReturn("23505").when(integrityViolation).getSQLState();
+    assertThat(ExceptionUtil.checkVariableIntegrityViolation(new PersistenceException(integrityViolation))).isTrue();
+  }
+
+  @Test
+  public void checkCrdbTransactionRetryException() {
+    assertThat(ExceptionUtil.checkCrdbTransactionRetryException(mock(SQLException.class))).isFalse();
+
+    SQLException retry = mock(SQLException.class);
+    doReturn("restart transaction").when(retry).getMessage();
+    doReturn(40001).when(retry).getErrorCode();
+    assertThat(ExceptionUtil.checkCrdbTransactionRetryException(retry)).isTrue();
+  }
+
+  @Test
+  public void checkDeadlockException() {
+    assertThat(ExceptionUtil.checkDeadlockException(mock(SQLException.class))).isFalse();
+
+    SQLException deadlock = mock(SQLException.class);
+    doReturn("40P01").when(deadlock).getSQLState();  // PostgreSQL
+    assertThat(ExceptionUtil.checkDeadlockException(deadlock)).isTrue();
+  }
+
+}