Mockito监视HSQLDB连接

Question

I am writing test cases for some code that uses HSQLDB to get its data from. However, there is a certain query/function called by my DAO which isn't supported in the in-memory database.

I am trying to return a custom ResultSet when this specific query is fired and default on the normal behavior otherwise (fetching from in memory database).

Relevant pieces of code:

db = new EmbeddedDatabaseBuilder().addScript("resources/create-test-db.sql")
    .addScript("resources/add-test-data.sql").build();
Connection conn = Mockito.spy(db.getConnection());

PreparedStatement mockPreparedStatement = Mockito.mock(PreparedStatement.class); 
when(conn.prepareStatement(query)).thenReturn(mockPreparedStatement);

And I pass on conn to my object. However, it seems HSQL is actually trying to run the query and thus, I get an error.

How should I do this?

Answer 1

模拟间谍时需要使用doReturn（） 。

doReturn(mockPreparedStatement).when(conn).prepareStatement(query);

Answer 2

Important gotcha on spying real objects!

Sometimes it's impossible or impractical to use when(Object) for stubbing spies. Therefore when using spies please consider doReturn|Answer|Throw() family of methods for stubbing.

Example:

List list = new LinkedList();
List spy = spy(list);
//Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
when(spy.get(0)).thenReturn("foo");
//You have to use doReturn() for stubbing
doReturn("foo").when(spy).get(0);

Source: Mockito Documentation

So in your case, try this:

doReturn(mockPreparedStatement).when(conn).prepareStatement(query);