From d0682d7b6227a8d5363e1ff6d5347bc732324131 Mon Sep 17 00:00:00 2001
From: Sebastian Zarnekow <sebastian.zarnekow@gmail.com>
Date: Mon, 8 Jan 2024 11:01:21 +0100
Subject: [PATCH] Keep the filter-chain consistent when using the LoggingTester

Manipulating the next-pointer of the linked list is error-prone
and corrupted the filter chain. It's safer to re-create the filter chain
from scratch by calling addFilter again.

Signed-off-by: Sebastian Zarnekow <sebastian.zarnekow@gmail.com>
---
 .../xtext/junit4/logging/LoggingTester.java   | 22 ++++++++++---------
 .../xtext/testing/logging/LoggingTester.java  | 22 ++++++++++---------
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/logging/LoggingTester.java b/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/logging/LoggingTester.java
index eac882771bf..eed565167f4 100644
--- a/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/logging/LoggingTester.java
+++ b/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/logging/LoggingTester.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2015, 2022 itemis AG (http://www.itemis.eu) and others.
+ * Copyright (c) 2015, 2024 itemis AG (http://www.itemis.eu) and others.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
@@ -333,16 +333,18 @@ private static List<Appender> appenderHierarchy(Logger logger) {
 	}
 
 	private static void removeFilter(Appender appender, Filter filter) {
-		if (Objects.equal(appender.getFilter(), filter)) {
-			appender.clearFilters();
-			appender.addFilter(filter.getNext());
-		} else {
-			for (Filter current = appender.getFilter(); (current != null); current = current.getNext()) {
-				if (Objects.equal(current.getNext(), filter)) {
-					current.setNext(filter.getNext());
-					return;
-				}
+		List<Filter> filtersToKeep = new ArrayList<>();
+		Filter present = appender.getFilter();
+		while (present != null) {
+			if (!Objects.equal(present, filter)) {
+				filtersToKeep.add(present);
 			}
+			present = present.getNext();
+		}
+		appender.clearFilters();
+		for(Filter addMe: filtersToKeep) {
+			addMe.setNext(null);
+			appender.addFilter(addMe);
 		}
 	}
 
diff --git a/org.eclipse.xtext.testing/src/org/eclipse/xtext/testing/logging/LoggingTester.java b/org.eclipse.xtext.testing/src/org/eclipse/xtext/testing/logging/LoggingTester.java
index ca0b24ea9dc..86f01e365b6 100644
--- a/org.eclipse.xtext.testing/src/org/eclipse/xtext/testing/logging/LoggingTester.java
+++ b/org.eclipse.xtext.testing/src/org/eclipse/xtext/testing/logging/LoggingTester.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2015, 2020 itemis AG (http://www.itemis.eu) and others.
+ * Copyright (c) 2015, 2024 itemis AG (http://www.itemis.eu) and others.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
@@ -69,17 +69,19 @@ private static List<Appender> appenderHierarchy(Logger logger) {
 	}
 
 	private static void removeFilter(Appender appender, Filter filter) {
-		if (Objects.equals(appender.getFilter(), filter)) {
-			appender.clearFilters();
-			appender.addFilter(filter.getNext());
-		} else {
-			for (Filter current = appender.getFilter(); current != null; current = current.getNext()) {
-				if (Objects.equals(current.getNext(), filter)) {
-					current.setNext(filter.getNext());
-					return;
-				}
+		List<Filter> filtersToKeep = new ArrayList<>();
+		Filter present = appender.getFilter();
+		while (present != null) {
+			if (!Objects.equals(present, filter)) {
+				filtersToKeep.add(present);
 			}
+			present = present.getNext();
 		}
+		appender.clearFilters();
+		filtersToKeep.forEach(addMe -> {
+			addMe.setNext(null);
+			appender.addFilter(addMe);
+		});
 	}
 
 	public static class LogCapture {