From 82a07fde25aa10847f1d29fb5576172e84c4d31b Mon Sep 17 00:00:00 2001
From: Phil Werli <phil.werli@teampicnic.com>
Date: Tue, 17 Jan 2023 07:33:56 +0100
Subject: [PATCH] Extend `MonoIdentity` Refaster rule (#465)

By flagging expressions of the form `mono.flux().next()`.
---
 .../tech/picnic/errorprone/refasterrules/ReactorRules.java   | 2 +-
 .../errorprone/refasterrules/ReactorRulesTestInput.java      | 5 ++++-
 .../errorprone/refasterrules/ReactorRulesTestOutput.java     | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

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
index fa8b50cb..b4cd081f 100644
--- 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
@@ -369,7 +369,7 @@ final class ReactorRules {
   static final class MonoIdentity<T> {
     @BeforeTemplate
     Mono<T> before(Mono<T> mono) {
-      return mono.switchIfEmpty(Mono.empty());
+      return Refaster.anyOf(mono.switchIfEmpty(Mono.empty()), mono.flux().next());
     }
 
     @BeforeTemplate
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
index c483d1e3..3377b40e 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -116,7 +116,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
-    return ImmutableSet.of(Mono.just(1).switchIfEmpty(Mono.empty()), Mono.<Void>empty().then());
+    return ImmutableSet.of(
+        Mono.just(1).switchIfEmpty(Mono.empty()),
+        Mono.just(2).flux().next(),
+        Mono.<Void>empty().then());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
index 619334ba..e5bee9e4 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -121,7 +121,7 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
-    return ImmutableSet.of(Mono.just(1), Mono.<Void>empty());
+    return ImmutableSet.of(Mono.just(1), Mono.just(2), Mono.<Void>empty());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {