retryIf(BooleanSupplier): when your boolean logic does not depend on the return of the Callable

[alb-i986]

If I'm not mistaken, the Retryer assumes that our boolean logic always depends on the return of the Callable.
But what if it didn't?

A workaround could be to have the Predicate to simply ignore its parameter:

Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
        .retryIfResult(
                     (ignored) -> { return myBooleanLogic(); }
        )
        ...

Or, better, give the user the option to build a Retryer that takes a BooleanSupplier.

BooleanSupplier myBS;

Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
        .retryIf(myBS) // **** new RetryerBuilder.retryIf
        .retryIfResult(Predicates.<Boolean>isNull())
        .retryIfExceptionOfType(IOException.class)
        .retryIfRuntimeException()
        .withStopStrategy(StopStrategies.stopAfterAttempt(3))
        .build();

It doesn't need to be "either a Predicate or a BooleanSupplier": I think it should be legal to build a Retryer with both:

• the predicate to check that the Callable doesn't return weird values like null
• the BooleanSupplier to check some other condition, not related to (the result of) the Callable.

public V call(Callable<V> callable) throws ExecutionException, RetryException {

....

if (!rejectionPredicate.apply(attempt)) {
return attempt.get();
}

if (!retryBooleanSupplier.getAsBoolean()){ // <---
return attempt.get();
}
...

Use case (Selenium UI testing)

I want to keep clicking on the 'refresh' button until some other element changes, e.g. the text of a div changes to "LOADED".

Here:

• my callable is "keep clicking on the 'refresh' button"

refreshBtn.click();

• my predicate is "has the text of the div changed to 'LOADED'?"

div.getText().contains("LOADED");

=> the predicate does not depend on the return of the Callable

If you agree with this I'll try to submit a PR.
Thanks

[JensRantil]

I would propose you implement a StopStrategy instead of adding a retryIf method.