Unit Testing: Logging and Dependency Injection

Question

So regards logging from SO and other sites on the Internet the best response seems to be:

void DoSomething() {
    Logger.Log(\"Doing something!\");
    // Code.         


        

Answer 1

Most logging frameworks allow you to provide custom implementation for components. You can use that configuration mechanism to provide your own implementations.

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For instance, Java's Log4J allows you to declare custom appenders, which are the components responsible for 'delivering' a LoggingEvent.

A logger can be easily mocked and injected using:

Appender appenderMock = EasyMock.createMock(Appender.class);
/* expect */ appenderMock.doAppend(EasyMock.isA(LoggingEvent.class));
EasyMock.replay(appenderMock);

Logger.getLogger(/* replace with your own */"My logger").addAppender(appenderMock);

EasyMock.verify(appenderMock);

This test only verifies that a logging event is sent, but you can refine it much more using EasyMock.