How to get a dependency service without starting a service?

[timur-han]

Hi,

Is there a way to get the instance of a dependency service without starting the service? I want to test certain functions using a dependency service but without actually starting the dependent service.

Regards,

Timur

[cprice404]

@timur87 if I'm understanding you correctly, the best way to do this for testing is implement a mock version of the dependency service. Then you can use the testutils with-app-with-config macro and pass it a list of services that you want it to include, including the mock version of the dependency service instead of the real version.

Would that suffice for your needs?

[timur-han]

@cprice404, thanks for the prompt answer again.

What I'm asking might be a really basic question :) What I need is an actual instance of the dependency service. Something similar to (services/get-service this :MyProtocol) except without "this" parameter here so that I can call it outside of the start or init functions.

[cprice404]

@timur87 so this is in test code? With a TK app booted up? Or are you saying you're trying to write tests that test the service without booting a TK app?

[timur-han]

It's not a test code, I'm working in repl interactively and want to see if the service really does its job. It's a persistency service, and I want to see if the things are really added. For that I need to get an instance of a dependency service, i.e., persistency service. All of this is happening in CIDER nREPL :)

[cprice404]

Ah, OK, so you do have a full instance of the TK app running then. There's probably a hacky way to do it; you can use this variable:

https://github.com/puppetlabs/trapperkeeper/blob/master/src/puppetlabs/trapperkeeper/core.clj#L122

to get a reference to the TrapperkeeperApp itself, and then use the get-service function from the TrapperkeeperApp protocol to get a reference to a service.

https://github.com/puppetlabs/trapperkeeper/blob/master/src/puppetlabs/trapperkeeper/app.clj#L5

I hate having that global variable in the code but this is what I put it in there for, as a last resort for this kind of situation. For a dev environment it'd probably be preferable to boot the tk-app explicitly in the repl and hold on to your own variable with a reference to the app, and access it through that, if possible.

[cprice404]

@timur87 did that work for your use case?

[timur-han]

Yes it did thanks for the prompt answers as always!