ResultSet在模拟databaseMetaData.getTables()方法时为空

Question

我正试图为一个类写一个单元测试用例，在那里我检查数据库中是否存在表。我使用DatabaseMetadata接口和Resultset接口来实现它。现在我试着写一个单元测试用例但是当mock

时

databasemetadata可以获得的()

方法，结果集为空。有人能告诉我我做错了什么吗?还有，有没有更好的方法来检查数据库中的表?

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import com.fasterxml.jackson.core.JsonProcessingException;
@Component
public class DataBaseTableScanner {

public DataBaseTableScanner() {
super();
}

private DataSource datasource;

@Autowired
public DataBaseTableScanner(DataSource datasource) {
this.datasource = datasource;
}

public void setDataSource(DataSource datasource) {
this.datasource = datasource;
}


public boolean checkForTableInDataBase(String entityName) throws SQLException {     
try(Connection con = datasource.getConnection()){
DatabaseMetaData databaseMetaData = con.getMetaData();
String tableName = entityName.toUpperCase();
String[] types = {"TABLE"};
resultSet = databaseMetaData.getTables(null, null, tableName, types);
boolean tableExistFlag = resultSet.next();
if(tableExistFlag) {
System.out.println("Check Table:: "+ tableName + " :Table exits in Database!!");
}else {
System.out.println("Check Table:: "+ tableName + " :Table does not exits in Database!!");
}
return tableExistFlag;

}
}
}

My Unit test case

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.when;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mapstruct.BeforeMapping;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
@RunWith(MockitoJUnitRunner.class)
public class DataBaseTableScannerTest {

@InjectMocks
DataBaseTableScanner dataBaseTableScanner;

@Mock
DataSource datasource;

@Mock
Connection connection;

@Mock
DatabaseMetaData databaseMetaData;

@Mock
ResultSet resultSet;


@Before
public void setUp() throws TenantResolvingException, TenantNotFoundException, SQLException {

dataBaseTableScanner.setDataSource(datasource);

when(datasource.getConnection()).thenReturn(connection);
when(connection.getMetaData()).thenReturn(databaseMetaData);
String tableName = null;
String[] types = null;
//      String tableName = "task";
//      String[] types = {"TABLE"};
when(databaseMetaData.getTables(null, null, tableName, types)).thenReturn(resultSet);

}


@Test
public void testIsTableExists() throws SQLException {
boolean tbexists = dataBaseTableScanner.checkForTableInDataBase("task");
assertTrue(tbexists);
}

Answer 1

用参数databaseMetaData.getTables(null, null, null, null))模拟方法，因为在setup方法中:

String tableName = null;
String[] types = null;

但是当你调用checkForTableInDataBase方法时，它内部调用getTables方法与不同的参数:

String tableName = entityName.toUpperCase();
String[] types = {"TABLE"};

所以你应该重写你当方法:

when(databaseMetaData.getTables(null, null, "task".toUpperCase(), {"TABLE"})).thenReturn(resultSet);

当然只有在你使用"task"作为dataBaseTableScanner.checkForTableInDataBase()

的输入参数