How to mock a local static variable?

Asked Feb 09 '16 at 14:49

Active Feb 09 '16 at 14:49

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My class uses a static local variable of org.slf4j.Logger. Is there some clever way of replacing this with a mock object for my testing? I'm thinking my best option is for MyClass to expose a setter?

Also, how can I mock the Logger object? I'd like to mock it such that when LOGGER.error(string, exception) is called I'd like to validate the error String.

public class MyClass {
  private static Logger LOGGER = LoggerFactory.getLogger(MyClass.class);

asked Feb 09 '16 at 14:49

ab11

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You may mock the logger and do what you're explaining, but that seems overkill and a bad practice to follow. Instead, you should write your tests to validate results on variables and/or if an exception was thrown rather than this. – Luiggi Mendoza Feb 09 '16 at 14:51
@DavidHaim it's a variable declared `static` and it's *local* for the class... – Luiggi Mendoza Feb 09 '16 at 14:51
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so it's just "static" – David Haim Feb 09 '16 at 14:52
Why not just mock/configure the underlying loggers/log system? – Thomas Feb 09 '16 at 14:52
Maybe the answer of this question helps you. http://stackoverflow.com/questions/5385161/powermock-testing-set-static-field-of-class – Sandra Parsick Feb 09 '16 at 14:53
... or another along these lines http://stackoverflow.com/questions/20014547/how-to-mock-local-variables-using-mockito-or-powermock – Jan Chimiak Feb 09 '16 at 14:54
just remove `private` and `final` :) no big deal, they just try to scare us. – ZhongYu Feb 09 '16 at 15:01
@LuiggiMendoza Why is this bad practice? Is there no value in asserting the actual log message is as expected? – ab11 Feb 09 '16 at 15:23
Because that's fragile and there may be tons of log messages. I recommend you to read more about how to write good unit tests. – Luiggi Mendoza Feb 09 '16 at 15:24

How to mock a local static variable?

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