From 4eb1cf676f3fdbf4db63cc5cc7164fc3770da0df Mon Sep 17 00:00:00 2001
From: Ulli Hafner <ullrich.hafner@gmail.com>
Date: Thu, 21 Dec 2023 15:05:29 +0100
Subject: [PATCH] Error titles should not be printed for merged messages.

---
 .../java/edu/hm/hafner/util/FilteredLog.java  | 15 ++++++---------
 .../edu/hm/hafner/util/FilteredLogTest.java   | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/src/main/java/edu/hm/hafner/util/FilteredLog.java b/src/main/java/edu/hm/hafner/util/FilteredLog.java
index 6dece00b..8173c53a 100644
--- a/src/main/java/edu/hm/hafner/util/FilteredLog.java
+++ b/src/main/java/edu/hm/hafner/util/FilteredLog.java
@@ -117,6 +117,9 @@ public void logError(final String message) {
         lock.lock();
         try {
             if (lines < maxLines) {
+                if (StringUtils.isNotBlank(title) && errorMessages.isEmpty()) {
+                    errorMessages.add(title);
+                }
                 errorMessages.add(message);
             }
             lines++;
@@ -155,13 +158,11 @@ public void logError(final String format, final Object... args) {
      */
     @FormatMethod
     public void logException(final Exception exception, final String format, final Object... args) {
+        logError(format, args);
+
         lock.lock();
         try {
-            if (lines < maxLines) {
-                errorMessages.add(String.format(format, args));
-                errorMessages.addAll(Arrays.asList(ExceptionUtils.getRootCauseStackTrace(exception)));
-            }
-            lines++;
+            errorMessages.addAll(Arrays.asList(ExceptionUtils.getRootCauseStackTrace(exception)));
         }
         finally {
             lock.unlock();
@@ -215,9 +216,6 @@ public List<String> getErrorMessages() {
             if (errorMessages.isEmpty()) {
                 return messages;
             }
-            if (StringUtils.isNotBlank(title)) {
-                messages.add(title);
-            }
             messages.addAll(errorMessages);
             if (lines > maxLines) {
                 messages.add(String.format("  ... skipped logging of %d additional errors ...", lines - maxLines));
@@ -255,7 +253,6 @@ public void merge(final FilteredLog other) {
         try {
             infoMessages.addAll(other.getInfoMessages());
             errorMessages.addAll(other.getErrorMessages());
-            lines += other.lines;
         }
         finally {
             lock.unlock();
diff --git a/src/test/java/edu/hm/hafner/util/FilteredLogTest.java b/src/test/java/edu/hm/hafner/util/FilteredLogTest.java
index 3bcfb423..d6b3b7db 100644
--- a/src/test/java/edu/hm/hafner/util/FilteredLogTest.java
+++ b/src/test/java/edu/hm/hafner/util/FilteredLogTest.java
@@ -98,7 +98,24 @@ void shouldMergeLogger() {
 
         assertThat(parent).hasOnlyInfoMessages("parent Info 1", "child Info 1")
                 .hasOnlyErrorMessages("Parent Errors", "parent Error 1", "Child Errors", "child Error 1");
-        assertThat(parent.size()).isEqualTo(2);
+        assertThat(parent.size()).isEqualTo(1);
+    }
+
+    @Test
+    void shouldSkipEmptyErrorLogWhenMerging() {
+        var parent = new FilteredLog("Parent Errors");
+
+        parent.logInfo("parent Info 1");
+
+        var child = new FilteredLog("Child Errors");
+        child.logInfo("child Info 1");
+        child.logError("child Error 1");
+
+        parent.merge(child);
+
+        assertThat(parent).hasOnlyInfoMessages("parent Info 1", "child Info 1")
+                .hasOnlyErrorMessages("Child Errors", "child Error 1");
+        assertThat(parent.size()).isZero();
     }
 
     @Test