From aeb79f90adbf50d41d331ae34887ad779a3e408b Mon Sep 17 00:00:00 2001
From: Phil Werli <phil.werli@teampicnic.com>
Date: Wed, 4 Oct 2023 18:44:52 +0200
Subject: [PATCH 1/2] Introduce `{Mono,Flux}OfType` Refaster rules

---
 .../refasterrules/ReactorRules.java           | 34 +++++++++++++++++++
 .../refasterrules/ReactorRulesTestInput.java  | 12 +++++++
 .../refasterrules/ReactorRulesTestOutput.java |  8 +++++
 3 files changed, 54 insertions(+)

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 68650e5b45..e1d8815e60 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
@@ -1053,6 +1053,40 @@ Flux<S> after(Flux<T> flux) {
     }
   }
 
+  /** Prefer {@link Mono#ofType(Class)} over more contrived alternatives. */
+  static final class MonoOfType<T, S> {
+    @BeforeTemplate
+    Mono<S> before(Mono<T> mono) {
+      return mono.filter(
+              Refaster.anyOf(
+                  Refaster.<S>clazz()::isInstance,
+                  x -> Refaster.<S>clazz().isAssignableFrom(x.getClass())))
+          .cast(Refaster.<S>clazz());
+    }
+
+    @AfterTemplate
+    Mono<S> after(Mono<T> mono) {
+      return mono.ofType(Refaster.<S>clazz());
+    }
+  }
+
+  /** Prefer {@link Flux#ofType(Class)} over more contrived alternatives. */
+  static final class FluxOfType<T, S> {
+    @BeforeTemplate
+    Flux<S> before(Flux<T> flux) {
+      return flux.filter(
+              Refaster.anyOf(
+                  Refaster.<S>clazz()::isInstance,
+                  x -> Refaster.<S>clazz().isAssignableFrom(x.getClass())))
+          .cast(Refaster.<S>clazz());
+    }
+
+    @AfterTemplate
+    Flux<S> after(Flux<T> flux) {
+      return flux.ofType(Refaster.<S>clazz());
+    }
+  }
+
   /** Prefer {@link Mono#flatMap(Function)} over more contrived alternatives. */
   static final class MonoFlatMap<S, T> {
     @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 b10b47f57b..388bab058a 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
@@ -364,6 +364,18 @@ Flux<Number> testFluxCast() {
     return Flux.just(1).map(Number.class::cast);
   }
 
+  ImmutableSet<Mono<Number>> testMonoOfType() {
+    return ImmutableSet.of(
+        Mono.just(1).filter(Number.class::isInstance).cast(Number.class),
+        Mono.just(2).filter(n -> Number.class.isAssignableFrom(n.getClass())).cast(Number.class));
+  }
+
+  ImmutableSet<Flux<Number>> testFluxOfType() {
+    return ImmutableSet.of(
+        Flux.just(1).filter(Number.class::isInstance).cast(Number.class),
+        Flux.just(2).filter(n -> Number.class.isAssignableFrom(n.getClass())).cast(Number.class));
+  }
+
   Mono<String> testMonoFlatMap() {
     return Mono.just("foo").map(Mono::just).flatMap(identity());
   }
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 98279c9060..1caa225341 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
@@ -357,6 +357,14 @@ Flux<Number> testFluxCast() {
     return Flux.just(1).cast(Number.class);
   }
 
+  ImmutableSet<Mono<Number>> testMonoOfType() {
+    return ImmutableSet.of(Mono.just(1).ofType(Number.class), Mono.just(2).ofType(Number.class));
+  }
+
+  ImmutableSet<Flux<Number>> testFluxOfType() {
+    return ImmutableSet.of(Flux.just(1).ofType(Number.class), Flux.just(2).ofType(Number.class));
+  }
+
   Mono<String> testMonoFlatMap() {
     return Mono.just("foo").flatMap(Mono::just);
   }

From 788d555d78c7dd9b4190d0b17316b18ff1d754a8 Mon Sep 17 00:00:00 2001
From: Stephan Schroevers <stephan.schroevers@teampicnic.com>
Date: Wed, 4 Oct 2023 21:41:13 +0200
Subject: [PATCH 2/2] Suggestions

---
 .../refasterrules/ReactorRules.java           | 24 +++++++------------
 .../refasterrules/ReactorRulesTestInput.java  | 12 ++++------
 .../refasterrules/ReactorRulesTestOutput.java |  8 +++----
 3 files changed, 16 insertions(+), 28 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 e1d8815e60..b9d79aa450 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
@@ -1056,34 +1056,26 @@ Flux<S> after(Flux<T> flux) {
   /** Prefer {@link Mono#ofType(Class)} over more contrived alternatives. */
   static final class MonoOfType<T, S> {
     @BeforeTemplate
-    Mono<S> before(Mono<T> mono) {
-      return mono.filter(
-              Refaster.anyOf(
-                  Refaster.<S>clazz()::isInstance,
-                  x -> Refaster.<S>clazz().isAssignableFrom(x.getClass())))
-          .cast(Refaster.<S>clazz());
+    Mono<S> before(Mono<T> mono, Class<S> clazz) {
+      return mono.filter(clazz::isInstance).cast(clazz);
     }
 
     @AfterTemplate
-    Mono<S> after(Mono<T> mono) {
-      return mono.ofType(Refaster.<S>clazz());
+    Mono<S> after(Mono<T> mono, Class<S> clazz) {
+      return mono.ofType(clazz);
     }
   }
 
   /** Prefer {@link Flux#ofType(Class)} over more contrived alternatives. */
   static final class FluxOfType<T, S> {
     @BeforeTemplate
-    Flux<S> before(Flux<T> flux) {
-      return flux.filter(
-              Refaster.anyOf(
-                  Refaster.<S>clazz()::isInstance,
-                  x -> Refaster.<S>clazz().isAssignableFrom(x.getClass())))
-          .cast(Refaster.<S>clazz());
+    Flux<S> before(Flux<T> flux, Class<S> clazz) {
+      return flux.filter(clazz::isInstance).cast(clazz);
     }
 
     @AfterTemplate
-    Flux<S> after(Flux<T> flux) {
-      return flux.ofType(Refaster.<S>clazz());
+    Flux<S> after(Flux<T> flux, Class<S> clazz) {
+      return flux.ofType(clazz);
     }
   }
 
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 388bab058a..cab6be19ef 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
@@ -364,16 +364,12 @@ Flux<Number> testFluxCast() {
     return Flux.just(1).map(Number.class::cast);
   }
 
-  ImmutableSet<Mono<Number>> testMonoOfType() {
-    return ImmutableSet.of(
-        Mono.just(1).filter(Number.class::isInstance).cast(Number.class),
-        Mono.just(2).filter(n -> Number.class.isAssignableFrom(n.getClass())).cast(Number.class));
+  Mono<Number> testMonoOfType() {
+    return Mono.just(1).filter(Number.class::isInstance).cast(Number.class);
   }
 
-  ImmutableSet<Flux<Number>> testFluxOfType() {
-    return ImmutableSet.of(
-        Flux.just(1).filter(Number.class::isInstance).cast(Number.class),
-        Flux.just(2).filter(n -> Number.class.isAssignableFrom(n.getClass())).cast(Number.class));
+  Flux<Number> testFluxOfType() {
+    return Flux.just(1).filter(Number.class::isInstance).cast(Number.class);
   }
 
   Mono<String> testMonoFlatMap() {
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 1caa225341..6e8005f65e 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
@@ -357,12 +357,12 @@ Flux<Number> testFluxCast() {
     return Flux.just(1).cast(Number.class);
   }
 
-  ImmutableSet<Mono<Number>> testMonoOfType() {
-    return ImmutableSet.of(Mono.just(1).ofType(Number.class), Mono.just(2).ofType(Number.class));
+  Mono<Number> testMonoOfType() {
+    return Mono.just(1).ofType(Number.class);
   }
 
-  ImmutableSet<Flux<Number>> testFluxOfType() {
-    return ImmutableSet.of(Flux.just(1).ofType(Number.class), Flux.just(2).ofType(Number.class));
+  Flux<Number> testFluxOfType() {
+    return Flux.just(1).ofType(Number.class);
   }
 
   Mono<String> testMonoFlatMap() {