Add new flux command sleep #495

[TobiasNx]

Resolves #495

[TobiasNx]

@fsteeg could you have a look, if this would be way worth to continue

[fsteeg]

Basic idea looks good. Some issues:

• PR description should reference the issue using closing keywords
• I'd copy an existing module, e.g. ObjectExceptionCatcher to get the types right (current build: does not compile cannot find symbol [...] class T)
• Formatting is off (comments), would also be avoided by copying an existing module
• I think the flux command should be just sleep
• The flux command needs to be added in src/main/resources/flux-commands.properties
• The Thread.sleep needs to be wrapped in a try-catch-block, handling InterruptedException, see e.g. in the OERSI SitemapReader

[TobiasNx]

Basic idea looks good. Some issues:

* PR description should reference the issue using closing keywords

* I'd copy an existing module, e.g. ObjectExceptionCatcher to get the types right (current build: does not compile `cannot find symbol [...] class T`)

* Formatting is off (comments), would also be avoided by copying an existing module

* I think the flux command should be just `sleep`

* The flux command needs to be added in `src/main/resources/flux-commands.properties`

* The `Thread.sleep` needs to be wrapped in a try-catch-block, handling `InterruptedException`, see e.g. in the OERSI [SitemapReader](https://gitlab.com/oersi/oersi-etl/-/blob/master/src/main/java/oersi/SitemapReader.java?ref_type=heads#L65)

Thanks I adjusted as suggested.
It is missing java tests. I am not sure how to add them for this specific function.

[blackwinter]

Would it make sense to enable this command to also support the Fix function use case? Just add another setter for the time unit and extract the sleep "action" into a dedicated method. Then we could easily reuse this class to implement the corresponding Fix function (see Catmandu).

[TobiasNx]

Would it make sense to enable this command to also support the Fix function use case? Just add another setter for the time unit and extract the sleep "action" into a dedicated method. Then we could easily reuse this class to implement the corresponding Fix function (see Catmandu).

I think this is a good idea, could you provide the code for this?

[blackwinter]

I think this is a good idea, could you provide the code for this?

Implemented in f069a04 and 18b6ae0.

Note that Catmandu defaults to SECONDS, and doesn't support NANOSECONDS and DAYS.

[TobiasNx]

@fsteeg can you review the additions that @blackwinter introduced. Also can you tell me how I would write a unit test for this? Not sure since it does change the result in a transformation.

[blackwinter]

Also can you tell me how I would write a unit test for this?

Initially, I thought we should just skip the test for this. But since you brought it up: You could verify that the process takes at least the amount of time that it was configured to sleep. It's not pretty, but it's something.

Not sure since it does change the result in a transformation.

You mean "it does not change the result", right?

[TobiasNx]

Also can you tell me how I would write a unit test for this?

Initially, I thought we should just skip the test for this. But since you brought it up: You could verify that the process takes at least the amount of time that it was configured to sleep. It's not pretty, but it's something.

Okay, I will have a look at this.

Not sure since it does change the result in a transformation.

You mean "it does not change the result", right?

Correct, it does not change the result

[TobiasNx]

Also can you tell me how I would write a unit test for this?

Initially, I thought we should just skip the test for this. But since you brought it up: You could verify that the process takes at least the amount of time that it was configured to sleep. It's not pretty, but it's something.

Not sure since it does change the result in a transformation.

You mean "it does not change the result", right?

@blackwinter is this the kind of test you had in mind?

[blackwinter]

Yes, thanks. However, I've modified your test a little (74bc15d).

Stylistic changes:

1. Switch from Instant/Duration to nanoTime().
2. Avoid static import statements.
3. Declare local variables as final.
4. Provide failure message if assertion fails.
5. Clean up formatting/indentation.

Functional changes:

1. Verify that sleep time doesn't exceed expected time by too much (otherwise you could make all tests pass by always sleeping for a very long time).
2. Add tests with explicit time unit.