Extend `{Flux,Mono}OnErrorComplete` Refaster rules by mohamedsamehsalah · Pull Request #1939 · PicnicSupermarket/error-prone-support

mohamedsamehsalah · 2025-10-31T14:54:15Z

Suggested commit message

Extend `{Flux,Mono}OnErrorComplete` Refaster rules (#1939)

mohamedsamehsalah · 2025-10-31T14:55:05Z

+    return Mono.just(1).onErrorComplete().doOnError(e -> {});
+  }
+
+  Mono<Integer> testMonoDoOnErrorClassOnErrorComplete() {


I admittedly don't know:

Why Refaster is not picking this line from the @BeforeTemplate.

How to fix it 😄

@Stephan202 @rickie , would appreciate the help 🙏

It's because of the specific signature of this doOnError overload; I'll push a fix. 👍

Sorry, I still don't quite get it 😅

This is the diff output:

diff (-expected +actual): @@ -600,7 +600,7 @@ } Mono<Integer> testMonoDoOnErrorClassOnErrorComplete() { - return Mono.just(1).doOnError(IllegalArgumentException.class, e -> {}).onErrorComplete(); + return Mono.just(1).onErrorComplete().doOnError(IllegalArgumentException.class, e -> {}); }

why didn't the @BeforeTemplate match the statement .doOnError(IllegalArgumentException.class, e -> {})

The signature of that particular overload is:

public final <E extends Throwable> Mono<T> doOnError(Class<E> exceptionType, final Consumer<? super E> onError) {

My change introduces a similar type constraint involving E extends Throwable to appease the type matching.

AHA! Makes sense; thanks a ton 💡

Stephan202

I added a commit. Suggested commit message:

Extend `{Flux,Mono}OnErrorComplete` Refaster rules (#1939)

As with #1938, I'd like to wrap up and merge ~~#1927~~ #1942 before this one, so that we stop seeing the Error Prone compatibility check failure on master.

Stephan202 · 2025-10-31T19:17:53Z

+  /** Calling {@link Mono#doOnError(Consumer)} after {@link Mono#onErrorComplete()} is redundant. */
+  static final class MonoDoOnErrorOnErrorComplete<T> {
+    @BeforeTemplate
+    Mono<T> before(Mono<T> mono, Consumer<? super Throwable> onError) {
+      return mono.onErrorComplete().doOnError(onError);
+    }
+
+    @AfterTemplate
+    Mono<T> after(Mono<T> mono, Consumer<? super Throwable> onError) {
+      return mono.doOnError(onError).onErrorComplete();
+    }
+  }


We're trying to make sure that Refaster rules are behavior preserving. While this rule and the ones below may rewrite the code in a way that was intended, it does change behavior. I'm in favour of doing what we do elsewhere: just drop the redundant operators. Users that meant the other behavior can manually update the code.

Makes sense 🧠 👍

Stephan202 · 2025-10-31T19:57:14Z

+    return Mono.just(1).onErrorComplete().doOnError(e -> {});
+  }
+
+  Mono<Integer> testMonoDoOnErrorClassOnErrorComplete() {


It's because of the specific signature of this doOnError overload; I'll push a fix. 👍

Stephan202 · 2025-10-31T19:57:34Z

+    @BeforeTemplate
+    Mono<T> before(
+        Mono<T> mono, Class<? extends Throwable> clazz, Consumer<? super Throwable> onError) {
+      return mono.onErrorComplete().doOnError(clazz, onError);


There's also a third doOnError overload; will add support.

github-actions · 2025-10-31T20:10:11Z

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

mohamedsamehsalah · 2025-11-01T13:30:34Z

Thanks @Stephan202 🙏

github-actions · 2025-11-25T19:52:42Z

Suggested commit message:

Extend `{Flux,Mono}OnErrorComplete` Refaster rules (#1939)

Teach `MonoOnErrorComplete` and `FluxOnErrorComplete` to rewrite
chained `onErrorComplete().doOnError(...)` patterns alongside
`onErrorResume` fallbacks.
This removes redundant callbacks and keeps Reactor error handling
consistent.

github-actions · 2025-11-25T19:54:32Z

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

rickie · 2025-11-26T08:48:03Z

/integration-test

github-actions · 2025-11-26T13:03:17Z

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

rickie

💖

rickie · 2025-11-27T10:51:21Z

As the IT repo's are not using Reactor, we don't need to run the IT.

github-actions · 2025-11-27T10:53:44Z

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

github-actions · 2025-11-28T09:47:51Z

Looks good. No mutations were possible for these changes.
Mutation testing report by Pitest. Review any surviving mutants by inspecting the line comments under Files changed.

sonarqubecloud · 2025-11-28T09:48:08Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

mohamedsamehsalah commented Oct 31, 2025

View reviewed changes

mohamedsamehsalah requested review from Stephan202 and rickie October 31, 2025 14:55

Stephan202 approved these changes Oct 31, 2025

View reviewed changes

Stephan202 added this to the 0.27.0 milestone Oct 31, 2025

Stephan202 added the improvement label Oct 31, 2025

Stephan202 changed the title ~~Introduce redundant Publisher#doOnError Refaster rules~~ Extend {Flux,Mono}OnErrorComplete Refaster rules Oct 31, 2025

Stephan202 force-pushed the mohamedsamehsalah/do-on-error branch from 2da97d1 to 0ef65ec Compare November 11, 2025 21:21

rickie force-pushed the mohamedsamehsalah/do-on-error branch from 0ef65ec to 4d3654a Compare November 25, 2025 19:51

rickie temporarily deployed to codex November 25, 2025 19:51 — with GitHub Actions Inactive

rickie force-pushed the mohamedsamehsalah/do-on-error branch from 4d3654a to a97a1b6 Compare November 26, 2025 13:00

rickie temporarily deployed to codex November 26, 2025 13:00 — with GitHub Actions Inactive

rickie approved these changes Nov 27, 2025

View reviewed changes

rickie force-pushed the mohamedsamehsalah/do-on-error branch from a97a1b6 to 1271238 Compare November 27, 2025 10:51

rickie temporarily deployed to codex November 27, 2025 10:51 — with GitHub Actions Inactive

mohamedsamehsalah and others added 2 commits November 28, 2025 10:45

Introduce redundant Publisher#doOnError Refaster rules

414fd08

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6d3dbd2

rickie force-pushed the mohamedsamehsalah/do-on-error branch from 1271238 to 6d3dbd2 Compare November 28, 2025 09:45

rickie temporarily deployed to codex November 28, 2025 09:45 — with GitHub Actions Inactive

rickie merged commit 0cdd56f into master Nov 28, 2025
19 checks passed

rickie deleted the mohamedsamehsalah/do-on-error branch November 28, 2025 10:15

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mohamedsamehsalah commented Oct 31, 2025 •

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