@WithJunitRule executes rule for every scenario

[ThomasRichtsfeld]

👓 What did you see?

When using a class annotated with @WithJunitRule that contains a rule it gets executed for each scenario.

✅ What did you expect to see?

I only expect the step classes that "inject" the rule in the constructor to execute the rule

📦 Which tool/library version are you using?

We are running instrumented tests on Android using test orchestrator

"io.cucumber:cucumber-android" version 4.10.0

🔬 How could we reproduce it?

Rule example:

@WithJunitRule
internal class GrantCameraPermissionRuleHolder {

    @get:Rule
    val grantPermissionRule: GrantPermissionRule = GrantPermissionRule.grant(Manifest.permission.CAMERA)
}

This rule is not injected anywhere, but it still gets executed for each scenario

[lsuski]

This is correct behaviour if I correctly understand your issue. Rule is executed every scenario the same as in normal Junit tests. Scenario == single junit test case. It doesn't matter where you inject test rule. Steps classes does not impose any lifecycle behaviour of test. You can have 1 scenario with 10 steps and every step can be implemented in different step class which means that you will have 10 steps classes objects created for every scenario. WithJunitRule is also created for every scenario no matter if you inject it somewhere or not because rule can setup some environment which is needed for test but not necesessarily has to be directly used in test code

[lsuski]

So in other words in Cucumber everything which is in glue package is considered to be used in scenario execution while in Junit it is limitted to test class which can cause some confusions but this is how Cucumber works

[ThomasRichtsfeld]

Yep, that's right. I understand that.
Is it then even possible to use Junit Rules that are applied only to specific step definition classes?
Let's say I want to create a test user with a rule before 2 of my 10 scenarios. How would that work with a Junit Rule?

This behavior was not fully clear to me when reading the documentation. In the demo app, you inject the scenario holder for compose into one of the step classes which made me think that this is how it works

[lsuski]

Demo example is very simple however as lifecycle of scenario execution ia a bit different there is no correlation between injecting rules and executing them. Currently is not possible to achieve what you want but in general this should be done by specifing some filter for scenario similarily as in @After annotation:

But as this is not currently implemented for WithJunitRule so it will not work

[ThomasRichtsfeld]

Alright, thanks. Do you think there will ever be a way to use rules for single scenarios? For the user creation case, I could call a static function in the step definition which is no problem, but for rules like GrantPermissionRule that is defined by Android it is impossible to use them only for certain scenarios.

Can you give an example of what you mean by "some filter for scenario similar as in @After annotation"?

[lsuski]

AS mentioned in @After annotation documentation a filter is a tag expression which matches particular scenario. So you can add tag above scenario:

@ScenarioWithGrantPermission
Scenario: Lorem ipsum

and then

@After("@ScenarioWithGrantPermission")
fun after() {...}

and this after ,ethod will be executed only for scenarios with @ScenarioWithGrantPermission tags. For tag expressions please read cucumber documentation https://cucumber.io/docs/cucumber/api/?lang=java#tag-expressions.

So similar mechasim could be implemented for WithJunitRule

[ThomasRichtsfeld]

It would be great if there is scenario support for the WithJunitRule.
As this is then more like a feature request, should we close the thread now?

[lsuski]

We can keep it open until PR will be created

[ThomasRichtsfeld]

Thanks a lot for the fast response @lsuski
Let me know if I can support in any way

[lsuski]

Sure, you can support by creating a PR with tag expression support in WithJunitRule :)

[lsuski]

With version 7,14,0 (not released yet) you will be able to specify tag expression in @WithJunitRule("@MyTag")