fix transaction isolation level check bug

.travis.yml

@@ -5,4 +5,5 @@ jdk:
 
 script: 
   - mvn clean test
+dist: trusty
   #- mvn clean test -Pperformance-test

neo4j-jdbc/src/main/java/org/neo4j/jdbc/impl/Neo4jConnectionImpl.java

@@ -75,6 +75,8 @@ protected Neo4jConnectionImpl(Properties properties, String url, int defaultHold
 		this.holdability = defaultHoldability;
 	}
 
+	Neo4jConnectionImpl() {}
+
 	public static boolean hasDebug(Properties properties) {
 		return "true".equalsIgnoreCase(properties.getProperty("debug", "false"));
 	}
@@ -229,7 +231,7 @@ protected void checkTypeParams(int resultSetType) throws SQLException {
 	 */
 	protected void checkTransactionIsolation(int level) throws SQLException {
 		// @formatter:off
-		int[] invalid = {
+		Integer[] invalid = {
 			TRANSACTION_NONE,
 			TRANSACTION_READ_COMMITTED,
 			TRANSACTION_READ_UNCOMMITTED,
@@ -238,7 +240,7 @@ protected void checkTransactionIsolation(int level) throws SQLException {
 		};
 
 		if(!Arrays.asList(invalid).contains(level)){
-			throw new SQLException();
+			throw new SQLException("Unsupported isolation level");
 		}
 		// @formatter:on
 	}

neo4j-jdbc/src/test/java/org/neo4j/jdbc/impl/Neo4jConnectionImplTest.java

@@ -0,0 +1,102 @@
+package org.neo4j.jdbc.impl;
+
+import org.junit.Test;
+
+import java.sql.DatabaseMetaData;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import static org.junit.Assert.fail;
+
+/**
+ * @description
+ * @time 创建时间:2019/9/3 0:44
+ * @param
+ * @author xin.gong
+ */
+public class Neo4jConnectionImplTest {
+
+    Neo4jConnectionImpl neo4jConnection = new Neo4jConnectionImpl(){
+        @Override public Statement createStatement() throws SQLException {
+            return null;
+        }
+
+        @Override public PreparedStatement prepareStatement(String sql) throws SQLException {
+            return null;
+        }
+
+        @Override public void setAutoCommit(boolean autoCommit) throws SQLException {
+
+        }
+
+        @Override public boolean getAutoCommit() throws SQLException {
+            return false;
+        }
+
+        @Override public void commit() throws SQLException {
+
+        }
+
+        @Override public void rollback() throws SQLException {
+
+        }
+
+        @Override public void close() throws SQLException {
+
+        }
+
+        @Override public boolean isClosed() throws SQLException {
+            return false;
+        }
+
+        @Override public DatabaseMetaData getMetaData() throws SQLException {
+            return null;
+        }
+
+        @Override public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
+            return null;
+        }
+
+        @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
+                throws SQLException {
+            return null;
+        }
+
+        @Override public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
+                throws SQLException {
+            return null;
+        }
+
+        @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency,
+                int resultSetHoldability) throws SQLException {
+            return null;
+        }
+
+        @Override public boolean isValid(int timeout) throws SQLException {
+            return false;
+        }
+    };
+    @Test public void checkTransactionIsolationShouldReturnNothing() {
+        Integer[] levels = {0, 1, 2, 4, 8};
+        for (int level : levels) {
+            try {
+                neo4jConnection.checkTransactionIsolation(level);
+            } catch (SQLException e) {
+                fail();
+            }
+        }
+    }
+
+    @Test public void checkTransactionIsolationShouldThrowExceptionWhenInputErrorLevel() {
+        Integer[] levels = {3, 5, 7, 9};
+        for (int level : levels) {
+            try {
+                neo4jConnection.checkTransactionIsolation(level);
+                fail();
+            } catch (SQLException e) {
+                // OK
+            }
+        }
+    }
+}