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Introduce MonoIdentity and MonoThen Refaster rules (#405)

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The `MonoIdentity` rule is a generalization of the existing
`MonoSwitchIfEmptyOfEmptyPublisher` rule.
This commit is contained in:
Paco van Beckhoven
2022-12-12 03:52:56 -04:00
committed by GitHub
parent 0153c1495f
commit 2cbd48ec47
3 changed files with 35 additions and 6 deletions
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25
error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
View File

@@ -365,13 +365,21 @@ final class ReactorRules {
}
}
/** Don't unnecessarily pass an empty publisher to {@link Mono#switchIfEmpty(Mono)}. */
static final class MonoSwitchIfEmptyOfEmptyPublisher<T> {
/** Don't unnecessarily transform a {@link Mono} to an equivalent instance. */
static final class MonoIdentity<T> {
@BeforeTemplate
Mono<T> before(Mono<T> mono) {
return mono.switchIfEmpty(Mono.empty());
}
// XXX: Review the suppression once NullAway has better support for generics. Keep an eye on
// https://github.com/uber/NullAway/issues?q=is%3Aopen+generics.
@BeforeTemplate
@SuppressWarnings("NullAway" /* False positive. */)
Mono<@Nullable Void> before2(Mono<@Nullable Void> mono) {
return mono.then();
}
@AfterTemplate
Mono<T> after(Mono<T> mono) {
return mono;
@@ -675,6 +683,19 @@ final class ReactorRules {
}
}
/** Prefer direct invocation of {@link Mono#then()}} over more contrived alternatives. */
static final class MonoThen<T> {
@BeforeTemplate
Mono<@Nullable Void> before(Mono<T> mono) {
return mono.flux().then();
}
@AfterTemplate
Mono<@Nullable Void> after(Mono<T> mono) {
return mono.then();
}
}
/**
* Prefer a collection using {@link MoreCollectors#toOptional()} over more contrived alternatives.
*/

8
error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
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@@ -115,8 +115,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
Flux.just("baz").switchIfEmpty(Flux.just("qux")));
}
Mono<Integer> testMonoSwitchIfEmptyOfEmptyPublisher() {
return Mono.just(1).switchIfEmpty(Mono.empty());
ImmutableSet<Mono<?>> testMonoIdentity() {
return ImmutableSet.of(Mono.just(1).switchIfEmpty(Mono.empty()), Mono.<Void>empty().then());
}
ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {
@@ -221,6 +221,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
Flux.concat(Mono.just("baz")));
}
Mono<Void> testMonoThen() {
return Mono.just("foo").flux().then();
}
Mono<Optional<String>> testMonoCollectToOptional() {
return Mono.just("foo").map(Optional::of).defaultIfEmpty(Optional.empty());
}

8
error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
View File

@@ -120,8 +120,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
Flux.just("foo").defaultIfEmpty("bar"), Flux.just("baz").defaultIfEmpty("qux"));
}
Mono<Integer> testMonoSwitchIfEmptyOfEmptyPublisher() {
return Mono.just(1);
ImmutableSet<Mono<?>> testMonoIdentity() {
return ImmutableSet.of(Mono.just(1), Mono.<Void>empty());
}
ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {
@@ -220,6 +220,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
Mono.just("foo").flux(), Mono.just("bar").flux(), Mono.just("baz").flux());
}
Mono<Void> testMonoThen() {
return Mono.just("foo").then();
}
Mono<Optional<String>> testMonoCollectToOptional() {
return Mono.just("foo").flux().collect(toOptional());
}