Support range filter in `@EnumSource`

[bjmi]

Sometimes it is necessary to test a consecutive range of enum constants in a unit test. The existing matchers of @EnumSource can't help here.
As Enum constants have a natural order, it would be useful to support a range in @EnumSource. If a bound is not specified, it is considered unbounded.

Following example would work then: all constants of ChronoUnit starting at WEEKS aren't supported by Instant.plus(..).

class InstantTests {

@EnumSource(from = "WEEKS")
@ParameterizedTest
void plus_unsupportedUnits(ChronoUnit unit) {
    Instant now = Instant.now();
    assertThrows(UnsupportedTemporalTypeException.class, () -> now.plus(1, unit));
}
...

Candidates are

• @EnumSource(from = "..", to = ".."),
• @EnumSource(begin = "..", end = "..") or
• @EnumSource(start = "..", end = "..")
• ...

The existing matchers could be applied to a specified range additionally.

Deliverables

• @EnumSource with optional from and to attributes
• Update documentation and release notes

[kaipe]

For this you can use EnumSet and LazyParams to cook your own parameterization solution ...

import java.util.EnumSet;
import static org.lazyparams.LazyParams.pickValue;

public class EnumParams {

    public static <E extends Enum<E>> E pickFromRange(
            String paramName, E from, E to) {

        if (null == from) {
            from = EnumSet.allOf(to.getDeclaringClass()).stream()
                    .findFirst().get();

        } else if (null == to) {
            to = EnumSet.allOf(from.getDeclaringClass()).stream()
                    .sorted(Comparator.reverseOrder())
                    .findFirst().get();
        }
        return (E) pickValue( paramName, EnumSet.range(from, to).toArray());
    }
}

The above method can then be used to achieve parameterization in midair during the execution of a regular JUnit test:

@Test
void plus_unsupportedUnits() {
    Instant now = Instant.now();
    ChronoUnit unit = EnumParams.pickFromRange("unit", ChronoUnit.WEEKS, null);
    assertThrows(UnsupportedTemporalTypeException.class, () -> now.plus(1, unit));
}

// With ConsoleLauncher the test result is presented like this:
//  JUnit Jupiter ✔
//  └─ InstantTests ✔
//     └─ plus_unsupportedUnits() ✔
//        ├─ plus_unsupportedUnits unit=Weeks ✔
//        ├─ plus_unsupportedUnits unit=Months ✔
//        ├─ plus_unsupportedUnits unit=Years ✔
//        ├─ plus_unsupportedUnits unit=Decades ✔
//        ├─ plus_unsupportedUnits unit=Centuries ✔
//        ├─ plus_unsupportedUnits unit=Millennia ✔
//        ├─ plus_unsupportedUnits unit=Eras ✔
//        └─ plus_unsupportedUnits unit=Forever ✔

[marcphilipp]

@kaipe LazyParams looks interesting! Is there some documentation explaining how it works?

I wonder if this would be a good addition to Pioneer's range sources. @bjmi WDYT?

FWIW, this can be achieved using a @MethodSource like this:

@ParameterizedTest
@MethodSource
void plus_unsupportedUnits(ChronoUnit unit) {
	Instant now = Instant.now();
	assertThrows(UnsupportedTemporalTypeException.class, () -> now.plus(1, unit));
}

static Set<ChronoUnit> plus_unsupportedUnits() {
	return EnumSet.range(ChronoUnit.WEEKS, ChronoUnit.FOREVER);
}

[sbrannen]

LazyParams looks interesting!

Indeed... a bit of magic. 🪄

Is there some documentation explaining how it works?

It's performing bytecode manipulation with a ByteBuddy agent.

I wonder if this would be a good addition to Pioneer's range sources.

I cannot speak for the Pioneer team, but my guess is that bytecode manipulation would be out of scope for a project like Pioneer.

[scordio]

I cannot speak for the Pioneer team, but my guess is that bytecode manipulation would be out of scope for a project like Pioneer.

Maybe not with bytecode manipulation but an @EnumRangeSource(from = "..", to = "..") might be a good fit with the other sources Pioneer offers, and that could be implemented with EnumSet::range, like in #4185 (comment).

[marcphilipp]

Is there some documentation explaining how it works?

It's performing bytecode manipulation with a ByteBuddy agent.

Yeah, I took a glance and saw that as well. But I was wondering what it manipulated it into. Does it use @ParameterizedTest under the hood?

I cannot speak for the Pioneer team, but my guess is that bytecode manipulation would be out of scope for a project like Pioneer.

Maybe not with bytecode manipulation but an @EnumRangeSource(from = "..", to = "..") might be a good fit with the other sources Pioneer offers, and that could be implemented with EnumSet::range, like in #4185 (comment).

That's what I meant as well.