Introduce MonoFluxThen and MonoVoidThen Refaster rules

PicnicSupermarket · Dec 9, 2022 · d4145a5 · d4145a5
1 parent 0153c14
commit d4145a5
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diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
@@ -675,6 +675,34 @@ Flux<T> after(Mono<T> mono) {
     }
   }
 
+  /** Don't unnecessarily convert {@link Mono} to {@link Flux}. */
+  @SuppressWarnings("VoidMissingNullable")
+  static final class MonoFluxThen<T> {
+    @BeforeTemplate
+    Mono<Void> before(Mono<T> mono) {
+      return mono.flux().then();
+    }
+
+    @AfterTemplate
+    Mono<Void> after(Mono<T> mono) {
+      return mono.then();
+    }
+  }
+
+  /** Don't unnecessarily call {@link Mono#then()} on a {@code Mono<Void>} . */
+  @SuppressWarnings("VoidMissingNullable")
+  static final class MonoVoidThen {
+    @BeforeTemplate
+    Mono<Void> before(Mono<Void> mono) {
+      return mono.then();
+    }
+
+    @AfterTemplate
+    Mono<Void> after(Mono<Void> mono) {
+      return mono;
+    }
+  }
+
   /**
    * Prefer a collection using {@link MoreCollectors#toOptional()} over more contrived alternatives.
    */

diff --git a/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -221,6 +221,14 @@ ImmutableSet<Flux<String>> testMonoFlux() {
         Flux.concat(Mono.just("baz")));
   }
 
+  Mono<Void> testMonoFluxThen() {
+    return Mono.just("foo").flux().then();
+  }
+
+  Mono<Void> testMonoVoidThen() {
+    return Mono.just("foo").then().then();
+  }
+
   Mono<Optional<String>> testMonoCollectToOptional() {
     return Mono.just("foo").map(Optional::of).defaultIfEmpty(Optional.empty());
   }

diff --git a/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -220,6 +220,14 @@ ImmutableSet<Flux<String>> testMonoFlux() {
         Mono.just("foo").flux(), Mono.just("bar").flux(), Mono.just("baz").flux());
   }
 
+  Mono<Void> testMonoFluxThen() {
+    return Mono.just("foo").then();
+  }
+
+  Mono<Void> testMonoVoidThen() {
+    return Mono.just("foo").then();
+  }
+
   Mono<Optional<String>> testMonoCollectToOptional() {
     return Mono.just("foo").flux().collect(toOptional());
   }