Introduce `@ConfigurationParametersResource` for use with `@Suite` classes

[robinjhector]

(This issue will describe my problems using JUnit together with another engine: Cucumber. But hopefully the proposed solution would increase JUnit Suite usability overall)

According to the documentation. the preferred way of running Cucumber, is via the JUnit Platform Suite.
I can set configuration parameters for the suite launcher discovery request, which then the underlaying engine can use, via @ConfigurationParameter, or @ConfigurationParameters.
It also defaults to parsing a junit-platform.properties file on classpath if found.

As long as I have set my configuration parameters as described above, the cucumber engine boots nicely, and everything works as expected.

However, when running Cucumber on the CLI, or via my IDE´s "run" functionality, Cucumber is not run via the the JUnit platform.
This makes configuring my tests to work with both JUnit and in standalone mode a bit tricky. Cucumber, in standalone mode, will try and look for a cucumber.properties file on classpath.

So I have a few options:

1. Duplicate the junit-platform.properties file, and save it as cucumber.properties.
   (Sad, keeping two files in sync is always a pain)
2. Keep my cucumber.properties file, and use annotations for the JUnit Suite (@ConfigurationParameter)
   (Same here, I will have some configuration in-code, and some in a properties file)
3. Do neither, and use System properties
   (I dislike it because it requires environmental setup for new developers, and may cause system-system variances)

Instead, it would be super helpful if we could feed configuration parameters to the JUnit Platform Suite, from a properties file of choice. If so I could have a single properties file for both my standalone cucumber runs, and my platform suite runs.

Suggestion

My idea is to introduce a new annotation, like:

@ConfigurationParameterFile("myown.properties")

(Naming tbd..)

Which would work just like @ConfigurationParameter, by reading the file and setting the config parameters.
Annotating with both @ConfigurationParameterFile and @ConfigurationParameter should be allowed. Where as @ConfigurationParameter takes precedence for a given key-value.

Deliverables

• New annotation for supplying configuration parameters via properties file.
• Extend SuiteLauncherDiscoveryRequestBuilder to parse the properties file, as specified in the new annotation

I'd be happy to take a stab at implementing this via a PR.
Feedback always welcome. Hope my points came across clearly, otherwise please let me know!

[mpkorstanje]

Fundamentally this problem is caused by a lack of first-class support for the JUnit Platform (#2849). In practice we are still dealing with JUnit 4 support with a translation layer bolted on for JUnit 5. This means that features such as selecting a line in a file for test execution using the file selector are simply not implemented by the popular IDEs and build systems.

If you happen to use InteliJ IDEA it might help to upvote IDEA-227508.

However, when running Cucumber on the CLI, or via my IDE´s "run" functionality, Cucumber is not run via the the JUnit platform.

This could also partially be resolved by the solutions outlined in cucumber/cucumber-jvm#2695.

I have no immediate objections to this proposal but I do have a mild preference towards a solution in Cucumber rather than one in JUnit 5. I would also very much welcome a PR for cucumber/cucumber-jvm#2695.

[sbrannen]

In general, I understand the desire to have such a feature.

It could be beneficial not only for use with @Suite classes but also when using the Launcher API programmatically.

For example, we could consider introducing @ConfigurationParametersFile as well as a new configurationParameters(Path) method in LauncherDiscoveryRequestBuilder as a complement to the existing configurationParameters(Map) method.

but I do have a mild preference towards a solution in Cucumber rather than one in JUnit 5.

If a solution tailored to Cucumber can be implemented, that would likely be ideal.

However, as stated above, I think having the ability to provide a "file" as a source for configuration parameters could be beneficial and would help alleviate duplication of configuration.

I would also very much welcome a PR in that direction.

You mean a PR for the Cucumber project?

[mpkorstanje]

You mean a PR for the Cucumber project?

Yes. Edited for clarity.

However, as stated above, I think having the ability to provide a "file" as a source for configuration parameters could be beneficial and would help alleviate duplication of configuration.

Do you think that there are use cases for file based configuration outside of this specific example? If Cucumber was not involved, I reckon most of these hypothetical use cases could be addressed by using @ConfigurationParameter as a meta-annotation.

That said, again, I don't have any immediate objection to this feature proposal on its own. It would in fact smooth over a problem that Cucumber users have. Though do think that it solves the underlying problem (a lack of support) in the wrong location.

[marcphilipp]

Team decision: Introduce @ConfigurationParametersResource and LauncherDiscoveryRequestBuilder.configurationParametersResource that allow specifying multiple properties files as classpath resources with last-one-wins semantics.

[marcphilipp]

@robinjhector Would you be interested in submitting a PR for this?

[robinjhector]

@robinjhector Would you be interested in submitting a PR for this?

Sure thing! I'll give it a go :)