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最近在看<<JUnit in Action>>对单元测试有了进一步的了解,以下是对数据库进行单元测试的一个例子.
这是一个web程序,servlet从request里提取SQL语句,然后从DB里取得数据返回给JSP.
首先,假设你的数据库访问代码与业务逻辑代码已经清晰地区分开来.那么我们就可以对数据库访问进行不同的单元测试.
1.对业务逻辑的单元测试--------这些测试的目标是将业务逻辑代码部分与数据库访问代码部分(持久化代码JDBC/JDO...)隔离开来,只对业务逻辑代码部分进行单元测试.采用什么策略?当然是mock objects.:-) 以下是例子:
public class AdminServlet extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException {}
public String getCommand(HttpServletRequest request) throws ServletException {} //从request里取得SQL语句
public Collection executeCommand(String command) throws Exception {}
public void callView(HttpServletRequest request) {} //传递数据给JSP
}
各种不同的方法的执行流程是:doGet接受HTTP请求并调用getCommand方法抽取出其中的SQL查询,接着调用executeCommand来执行数据库调用并将结果以一个Collection返回.结果放入HTTP请求中,最后,doGet调用callView来激活给用户显示结果的JSP页面.
现在的问题在于如何在不执行由executeCommand运行的数据库访问代码的前提下对doGet,getCommand,callView进行单元测试.方法是建立数据库访问层.为数据库访问层建立一个接口.有了接口就可以采用mock objects策略来对数据库访问层进行单元测试.
数据库访问层接口:
public interface DataAccessManager {
Collection execute(String sql) throws Exception;
}
接着重构AdminServlet类
public class AdminServlet extends HttpServlet
{
// [...]
private DataAccessManager dataManager;
public void init() throws ServletException
{
super.init();
try
{
this.dataManager = new JdbcDataAccessManager();
catch (NamingException e)
{
throw new ServletException(e);
}
}
public Collection executeCommand(String command)
throws Exception
{
return this.dataManager.execute(command);
}
}
JdbcDataAccessManager类是DataAccessManager的执行类. 在进行单元测试时我们所要做的是建立一个DataAccessManager的mock objects实现来替换真实的JdbcDataAccessManager.
继续重构成AdminServlet:
public class AdminServlet extends HttpServlet
{
// [...]
private DataAccessManager dataManager;
public DataAccessManager getDataAccessManager()
{
return this.dataManager;
}
public void setDataAccessManager(DataAccessManager manager)
{
this.dataManager = manager;
}
public void init() throws ServletException
{
super.init();
try
{
setDataAccessManager(new JdbcDataAccessManager());
}
catch (NamingException e)
{
throw new ServletException(e);
}
}
public Collection executeCommand(String command)
throws Exception
{
return this.dataManager.execute(command);
}
}
添加一个setter DataAccessManager的方法来便于传入mock objects.
下面就是怎样来建立mock objects,我们用DynaMock API来实现,当然你也可以用easymock,JMock等来实现.下面是一个编写DynaMock TestCase的模板:
import java.util.ArrayList;
import com.mockobjects.dynamic.Mock;
import com.mockobjects.dynamic.C;
import junit.framework.TestCase;
public class TestAdminServletDynaMock extends TestCase
{
public void testSomething() throws Exception
{
Mock mockManager = new Mock(DataAccessManager.class);
DataAccessManager manager =
(DataAccessManager) mockManager.proxy();
mockManager.expectAndReturn("execute", C.ANY_ARGS,
new ArrayList());
AdminServlet servlet = new AdminServlet();
servlet.setDataAccessManager(manager);
// Call the method to test here. For example:
// manager.doGet(request, response)
// [...]
}
}
你用DynaMockAPI创建一个DataAccessManager mock objects,接下来当调用execute方法时你让mock objects返回你设定的值.那么AdminServlet其余的方法就可以很方便的用这个值进行单元测试了.
2.对数据库访问的单元测试--------数据库访问代码用一套持久化API访问你的数据库.这类测试的目标是验证你是否正确使用了持久化API.测试策略主要是采用mock objects来模拟持久化API在不与数据库连接并且不在容器内的情况下运行测试.
现在我们来测试数据库访问代码.JDBC,JDO等等本身设计得很好，并且使用java接口,这样一来就非常适宜于mock objects策略.对于JDBC API 来说，有现成的mock objects包(MockObjects.com JDBC API),它比较成熟，已经为JDBC代码单元测试作好了准备.下面是我们要测的数据库访问代码:
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collection;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import org.apache.commons.beanutils.RowSetDynaClass;
public class JdbcDataAccessManager implements DataAccessManager
{
private DataSource dataSource;
public JdbcDataAccessManager() throws NamingException
{
this.dataSource = getDataSource();
}
protected DataSource getDataSource() throws NamingException
{
InitialContext context = new InitialContext();
DataSource dataSource =
(DataSource) context.lookup("java:/DefaultDS");
return dataSource;
}
protected Connection getConnection() throws SQLException
{
return this.dataSource.getConnection();
}
public Collection execute(String sql) throws Exception
{
Connection connection = getConnection();
// For simplicity, we'll assume the SQL is a SELECT query
ResultSet resultSet =
connection.createStatement().executeQuery(sql);
RowSetDynaClass rsdc = new RowSetDynaClass(resultSet);
resultSet.close();
connection.close();
return rsdc.getRows();
}
}
数据库访问代码主要在execute方法内,我们要给里面的使用到的JDBC API提供mock objects,首先我们需要模拟Connection对象，接着模拟的Connection对象就可以返回mock ResultSet,mock Statement等等.现在我们关心的问题是如何将一个mock Connection对象传递给JdbcDataAccessManager类.很简单,再写一个JdbcDataAccessManager的子类,添加setter方法,我们测了这个子类也就相当于测了DataAccessManager类.
import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.NamingException;
import javax.sql.DataSource;
public class TestableJdbcDataAccessManager
extends JdbcDataAccessManager
{
private Connection connection;
public TestableJdbcDataAccessManager() throws NamingException
{
super();
}
public void setConnection(Connection connection)
{
this.connection = connection;
}
protected Connection getConnection() throws SQLException
{
return this.connection;
}
protected DataSource getDataSource() throws NamingException
{
return null;
}
}
下面我们来编写测试代码:
import java.sql.SQLException;
import java.util.Collection;
import java.util.Iterator;
import org.apache.commons.beanutils.DynaBean;
import com.mockobjects.sql.MockConnection2;
import com.mockobjects.sql.MockResultSetMetaData;
import com.mockobjects.sql.MockSingleRowResultSet;
import com.mockobjects.sql.MockStatement;
import junit.framework.TestCase;
public class TestJdbcDataAccessManagerMO4 extends TestCase
{
private MockSingleRowResultSet resultSet;
private MockResultSetMetaData resultSetMetaData;
private MockStatement statement;
private MockConnection2 connection;
private TestableJdbcDataAccessManager manager;
protected void setUp() throws Exception
{
resultSetMetaData = new MockResultSetMetaData();
resultSet = new MockSingleRowResultSet();
resultSet.setupMetaData(resultSetMetaData);
statement = new MockStatement();
connection = new MockConnection2();
connection.setupStatement(statement);
manager = new TestableJdbcDataAccessManager();
manager.setConnection(connection);
}
protected void tearDown()
{
connection.verify();
statement.verify();
resultSet.verify();
}
public void testExecuteOk() throws Exception
{
String sql = "SELECT * FROM CUSTOMER";
statement.addExpectedExecuteQuery(sql, resultSet);
String[] columnsUppercase = new String[] {"FIRSTNAME",
"LASTNAME"};
String[] columnsLowercase = new String[] {"firstname",
"lastname"};
String[] columnClasseNames = new String[] {
String.class.getName(), String.class.getName()};
resultSetMetaData.setupAddColumnNames(columnsUppercase);
resultSetMetaData.setupAddColumnClassNames(
columnClasseNames);
resultSetMetaData.setupGetColumnCount(2);
resultSet.addExpectedNamedValues(columnsLowercase,
new Object[] {"John", "Doe"});
connection.setExpectedCreateStatementCalls(1);
connection.setExpectedCloseCalls(1);
Collection result = manager.execute(sql);
Iterator beans = result.iterator();
assertTrue(beans.hasNext());
DynaBean bean1 = (DynaBean) beans.next();
assertEquals("John", bean1.get("firstname"));
assertEquals("Doe", bean1.get("lastname"));
assertTrue(!beans.hasNext());
}
public void testExecuteCloseConnectionOnException()
throws Exception
{
String sql = "SELECT * FROM CUSTOMER";
statement.setupThrowExceptionOnExecute(
new SQLException("sql error"));
connection.setExpectedCloseCalls(1);
try
{
manager.execute(sql);
fail("Should have thrown a SQLException");
}
catch (SQLException expected)
{
assertEquals("sql error", expected.getMessage());
}
}
}
首先,我们用mockobject.sql包里的MockConnection建立一个 Mock Connection对象,TestableJdbcDataAccessManager把它设置进去,然后再设置Mock Statement和Mock ResultSet,并且设置Mock ResultSet返回的期望值.然后我们就可以来进行单元测试了, 去验证数据库访问代码的返回值.注意:在tearDown()里的connection,statement和resultSet的verify方法.这是对模拟对象添加的预期验证.比如statement.addExpectedExecuteQuery(sql, resultSet) statement.verify()就会验证SQL字符串是不是就是不做任何修改地传递过来的那个,执行结果是不是resultSet对象.connection.setExpectedCreateStatementCalls(1) connection.verify就会验证是否仅创建了一个Statement.
3.数据库集成单元测试--------这类测试主要是检测数据库的功能:连接,查询,存储过程,触发,约束以及引用完整性.这些测试必须在容器内并且有数据源相连的情况下进行.有很多第三方工具可以用来做这种测试,比如用cactus来进行容器内测试,DbUnit来预载测试数据库.
为了运行集成单元测试,我们的测试框架需要有两个功能:将测试数据预置进数据库的能力和从运行的容器内进行测试的能力.
我们的测试策略是用JBoss做为J2EE容器.MySQL作为测试数据库.Cactus作为测试代理.DbUnit作为装载及比较数据的工具,Ant作为运行测试工具.下面让我们进入测试吧.
编写真正的JdbcDataAccessManager类:
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collection;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import org.apache.commons.beanutils.RowSetDynaClass;
public class JdbcDataAccessManager implements DataAccessManager
{
private DataSource dataSource;
public JdbcDataAccessManager() throws NamingException
{
this.dataSource = getDataSource();
}
protected DataSource getDataSource() throws NamingException
{
InitialContext context = new InitialContext();
DataSource dataSource =
(DataSource) context.lookup("java:/MySqlDS");
return dataSource;
}
protected Connection getConnection() throws SQLException
{
return this.dataSource.getConnection();
}
public Collection execute(String sql) throws Exception
{
Connection connection = getConnection();
// For simplicity, we'll assume the SQL is a SELECT query
ResultSet resultSet =
connection.createStatement().executeQuery(sql);
RowSetDynaClass rsdc = new RowSetDynaClass(resultSet);
resultSet.close();
connection.close();
return rsdc.getRows();
}
}
注意要配置一个mysql数据源.假设在mysql数据库里建了一个叫jbossdb的数据库.然后在%JBOSS_HOME%/docs/examples/jca目录下找到mysql-ds.xml文件,对它进行编辑.
<?xml version="1.0" encoding="UTF-8"?>
<!-- ===================================================================== -->
<!-- -->
<!-- JBoss Server Configuration -->
<!-- -->
<!-- ===================================================================== -->
<!-- $Id: mysql-ds.xml,v 1.1 2002/07/22 22:57:24 d_jencks Exp $ -->
<!-- ==================================================================== -->
<!-- Datasource config for MySQL using 2.0.11 driver -->
<!-- ==================================================================== -->
<datasources>
<local-tx-datasource>
<jndi-name>MySqlDS</jndi-name>
<connection-url>jdbc:mysql://localhost:3306/jbossdb</connection-url>
<driver-class>org.gjt.mm.mysql.Driver</driver-class>
<user-name>sa</user-name>
<password></password>
</local-tx-datasource>
</datasources>
保存以后考到%JBOSS_HOME%/server/default/deploy目录下(假设你的JBOSS服务器以default模式起).下面编写测试代码:
import java.util.Collection;
import java.util.Iterator;
import javax.naming.InitialContext;
import org.apache.cactus.ServletTestCase;
import org.apache.commons.beanutils.DynaBean;
import org.dbunit.database.DatabaseDataSourceConnection;
import org.dbunit.database.IDatabaseConnection;
import org.dbunit.dataset.IDataSet;
import org.dbunit.dataset.xml.FlatXmlDataSet;
import org.dbunit.operation.DatabaseOperation;
public class TestJdbcDataAccessManagerIC extends ServletTestCase
{
protected void setUp() throws Exception
{
IDatabaseConnection connection =
new DatabaseDataSourceConnection(new InitialContext(),
"java:/MySqlDS");
IDataSet dataSet = new FlatXmlDataSet(
this.getClass().getResource(
"/junitbook/database/data.xml"));
try
{
DatabaseOperation.CLEAN_INSERT.execute(connection,
dataSet);
}
finally
{
connection.close();
}
}
public void testExecuteOk() throws Exception
{
JdbcDataAccessManager manager =
new JdbcDataAccessManager();
Collection result =
manager.execute("SELECT * FROM CUSTOMER");
Iterator beans = result.iterator();
assertTrue(beans.hasNext());
DynaBean bean1 = (DynaBean) beans.next();
assertEquals("John", bean1.get("firstname"));
assertEquals("Doe", bean1.get("lastname"));
assertTrue(!beans.hasNext());
}
}
在setup()里我们利用DbUnit从一个xml文件转载测试数据到数据库里.这里需要一个xml文件data.xml
<dataset>
<CUSTOMER FIRSTNAME="John" LASTNAME="Doe"/>
</dataset>
可以把它和测试代码文件放在同一个目录下.这个TestCase就是先在数据库里的Customer表里加一条记录,再进行测试.table我们可以利用ant来建,先编写一个data.sql
CREATE TABLE CUSTOMER (lastname varchar primary key,
firstname varchar);
.注意所有文件以及需要的包的安放按照junit test的传统安置方式安放.好,要用ant来运行了,先写build.xml
build.properties
cactus.home.jboss3x = E:/JBoss/jboss-3.2.3/jboss-3.2.3
database = //localhost:3306/jbossdb
lib.dir = ../repository
mysqldb.jar = ${cactus.home.jboss3x}/server/default/lib/mm.mysql-2.0.4-bin.jar
beanutils.jar = ${lib.dir}/commons-beanutils/jars/commons-beanutils-1.6.1.jar
collections.jar = ${lib.dir}/commons-collections/jars/commons-collections-2.1.jar
servlet.jar = ${lib.dir}/servletapi/jars/servletapi-2.3.jar
cactus.jar = ${lib.dir}/cactus/jars/cactus-1.6.1.jar
cactus.ant.jar = ${lib.dir}/cactus/jars/cactus-ant-1.6.1.jar
aspectjrt.jar = ${lib.dir}/aspectj/jars/aspectjrt-1.1.1.jar
dbunit.jar = ${lib.dir}/dbunit/jars/dbunit-1.5.5.jar
exml.jar = ${lib.dir}/dbunit/jars/exml-dbunit-1.5.5.jar
logging.jar = ${lib.dir}/commons-logging/jars/commons-logging-1.0.3.jar
httpclient.jar = ${lib.dir}/commons-httpclient/jars/commons-httpclient-2.0-rc1.jar
build.xml
<?xml version="1.0"?>
<project name="Database" default="test" basedir=".">
<property file="build.properties.sample"/>
<property name="conf.dir" location="conf"/>
<target name="compile">
<mkdir dir="target/classes"/>
<javac destdir="target/classes" srcdir="src/java">
<classpath>
<pathelement location="${beanutils.jar}"/>
<pathelement location="${servlet.jar}"/>
</classpath>
</javac>
</target>
<target name="war" depends="compile">
<war destfile="target/database.war"
webxml="src/webapp/WEB-INF/web.xml">
<classes dir="target/classes"/>
<lib file="${beanutils.jar}"/>
<lib file="${collections.jar}"/>
</war>
</target>
<target name="createdb" depends="war">
<sql driver="org.gjt.mm.mysql.Driver"
url="jdbc:mysql {database}"
userid="root"
password="">
<fileset dir="${conf.dir}">
<include name="data.sql" />
</fileset>
<classpath>
<pathelement location="${mysqldb.jar}"/>
</classpath>
</sql>
</target>
<target name="clean">
<delete dir="target"/>
</target>
<!-- Targets related to Cactus testing -->
<target name="compile.cactustest" depends="createdb">
<mkdir dir="target/cactus-test-classes"/>
<javac destdir="target/cactus-test-classes"
srcdir="src/test-cactus">
<classpath>
<pathelement location="target/classes"/>
<pathelement location="${beanutils.jar}"/>
<pathelement location="${dbunit.jar}"/>
<pathelement location="${cactus.jar}"/>
</classpath>
</javac>
<copy todir="target/cactus-test-classes">
<fileset dir="src/test-cactus">
<include name="**/*.xml"/>
</fileset>
</copy>
</target>
<target name="test" depends="war,compile.cactustest">
<taskdef resource="cactus.tasks">
<classpath>
<pathelement location="${cactus.ant.jar}"/>
<pathelement location="${cactus.jar}"/>
<pathelement location="${logging.jar}"/>
<pathelement location="${aspectjrt.jar}"/>
<pathelement location="${httpclient.jar}"/>
</classpath>
</taskdef>
<cactifywar srcfile="target/database.war"
destfile="target/test.war">
<classes dir="target/cactus-test-classes"/>
<lib file="${dbunit.jar}"/>
<lib file="${exml.jar}"/>
</cactifywar>
<cactus warfile="target/test.war" fork="yes" printsummary="yes"
haltonerror="true" haltonfailure="true">
<containerset>
<jboss3x dir="${cactus.home.jboss3x}"
output="target/jbossresult.txt">
</jboss3x>
</containerset>
<formatter type="brief" usefile="false"/>
<batchtest>
<fileset dir="src/test-cactus">
<include name="**/TestJdbcDataAccessManagerIC.java"/>
</fileset>
</batchtest>
<classpath>
<pathelement location="target/classes"/>
<pathelement location="target/cactus-test-classes"/>
<pathelement location="${dbunit.jar}"/>
</classpath>
</cactus>
</target>
</project>
接着我们就可以run case了,我试了一下没问题,若有问题,应该是配置或版本出了问题.
我本人对JUnit进行数据库测试的看法是,在测试之前一定要有一个好的测试策略,在这基础之上在进行测试代码的编写.对数据库业务逻辑和数据库访问代码的测试代码编写相对简单一些.对数据库进行集成测试要复杂和麻烦一些,但在这过程中能学到不少东西和加深对一些过程和配置的理解.
以上是我一些不成熟的学习心得,在这抛砖引玉,希望更多的同行来讨论. |
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