Introduce FluxEmpty Refaster rule

PicnicSupermarket · Oct 6, 2023 · cd1f5f9 · cd1f5f9
1 parent 5596b58
commit cd1f5f9
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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
@@ -391,6 +391,25 @@ Flux<T> after(Flux<T> flux, T object) {
     }
   }
 
+  /** Prefer {@link Flux#empty()} over more contrived ways of creating an empty flux. */
+  static final class FluxEmpty<T> {
+    @BeforeTemplate
+    Flux<T> before() {
+      return Refaster.anyOf(
+          Flux.just(),
+          Flux.concat(),
+          Flux.concatDelayError(),
+          Flux.firstWithSignal(),
+          Flux.merge(),
+          Flux.mergeSequential());
+    }
+
+    @AfterTemplate
+    Flux<T> after() {
+      return Flux.empty();
+    }
+  }
+
   /** Don't unnecessarily transform a {@link Mono} to an equivalent instance. */
   static final class MonoIdentity<T> {
     @BeforeTemplate

diff --git a/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -136,6 +136,16 @@ ImmutableSet<Flux<String>> testFluxDefaultIfEmpty() {
         Flux.just("baz").switchIfEmpty(Flux.just("qux")));
   }
 
+  ImmutableSet<Flux<Void>> testFluxEmpty() {
+    return ImmutableSet.of(
+        Flux.just(),
+        Flux.concat(),
+        Flux.concatDelayError(),
+        Flux.firstWithSignal(),
+        Flux.merge(),
+        Flux.mergeSequential());
+  }
+
   ImmutableSet<Mono<?>> testMonoIdentity() {
     return ImmutableSet.of(
         Mono.just(1).switchIfEmpty(Mono.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
@@ -141,6 +141,11 @@ ImmutableSet<Flux<String>> testFluxDefaultIfEmpty() {
         Flux.just("foo").defaultIfEmpty("bar"), Flux.just("baz").defaultIfEmpty("qux"));
   }
 
+  ImmutableSet<Flux<Void>> testFluxEmpty() {
+    return ImmutableSet.of(
+        Flux.empty(), Flux.empty(), Flux.empty(), Flux.empty(), Flux.empty(), Flux.empty());
+  }
+
   ImmutableSet<Mono<?>> testMonoIdentity() {
     return ImmutableSet.of(
         Mono.just(1),