Changed the truncate summary to cut build logs from top (#272)

src/main/java/io/jenkins/plugins/checks/api/ChecksOutput.java

@@ -76,13 +76,7 @@ public Optional<String> getText() {
      * @return Text, truncated to maxSize with truncation message if appropriate.
      */
     public Optional<String> getText(final int maxSize) {
-        return Optional.ofNullable(text)
-                .map(s -> new TruncatedString.Builder()
-                        .setChunkOnNewlines()
-                        .setTruncateStart()
-                        .addText(s.toString())
-                        .build()
-                        .buildByChars(maxSize));
+        return Optional.ofNullable(text).map(s -> s.build(maxSize));
     }
 
     public List<ChecksAnnotation> getChecksAnnotations() {

src/main/java/io/jenkins/plugins/checks/status/FlowExecutionAnalyzer.java

@@ -36,6 +36,8 @@
 class FlowExecutionAnalyzer {
     private static final Logger LOGGER = Logger.getLogger(FlowExecutionAnalyzer.class.getName());
     private static final String TRUNCATED_MESSAGE = "\n\nOutput truncated.";
+    private static final String TRUNCATED_MESSAGE_BUILD_LOG = "Build log truncated.\n\n";
+    private static final int MAX_MESSAGE_SIZE_TO_CHECKS_API = 65_535;
 
     private final Run<?, ?> run;
     private final FlowExecution execution;
@@ -132,9 +134,12 @@ private Pair<String, String> processErrorOrWarningRow(final FlowGraphTable.Row r
             nodeTextBuilder.append(String.format("**Error**: *%s*", displayName));
             nodeSummaryBuilder.append(String.format("```%n%s%n```%n", displayName));
             if (!suppressLogs) {
-                String log = getLog(flowNode);
+                // -2 for "\n\n" at the end of the summary and -30 for buffer
+                String logTemplate = "<details>%n<summary>Build log</summary>%n%n```%n%s%n```%n</details>";
+                int maxMessageSize = MAX_MESSAGE_SIZE_TO_CHECKS_API - nodeSummaryBuilder.length() - logTemplate.length() - 32;
+                String log = getLog(flowNode, maxMessageSize);
                 if (StringUtils.isNotBlank(log)) {
-                    nodeSummaryBuilder.append(String.format("<details>%n<summary>Build log</summary>%n%n```%n%s%n```%n</details>", log));
+                    nodeSummaryBuilder.append(String.format(logTemplate, log));
                 }
             }
         }
@@ -197,7 +202,7 @@ private String getPotentialTitle(final FlowNode flowNode, final ErrorAction erro
     }
 
     @CheckForNull
-    private static String getLog(final FlowNode flowNode) {
+    private static String getLog(final FlowNode flowNode, final int maxMessageSize) {
         LogAction logAction = flowNode.getAction(LogAction.class);
         if (logAction == null) {
             return null;
@@ -209,7 +214,15 @@ private static String getLog(final FlowNode flowNode) {
 
             String outputString = out.toString(StandardCharsets.UTF_8);
             // strip ansi color codes
-            return outputString.replaceAll("\u001B\\[[;\\d]*m", "");
+            String log = outputString.replaceAll("\u001B\\[[;\\d]*m", "");
+
+            return new TruncatedString.Builder()
+                    .setChunkOnNewlines()
+                    .setTruncateStart()
+                    .withTruncationText(TRUNCATED_MESSAGE_BUILD_LOG)
+                    .addText(log)
+                    .build()
+                    .build(maxMessageSize);
         }
         catch (IOException e) {
             LOGGER.log(Level.WARNING, String.format("Failed to extract logs for step '%s'",

src/test/java/io/jenkins/plugins/checks/api/ChecksOutputTest.java

@@ -30,10 +30,9 @@ void shouldBuildCorrectlyWithAllFields() {
                 .addImage(images.get(1))
                 .build();
 
-        ChecksOutputAssert.assertThat(checksOutput)
-                .hasTitle(Optional.of(TITLE))
-                .hasSummary(Optional.of(SUMMARY))
-                .hasText(Optional.of(TEXT));
+        assertThat(checksOutput.getTitle()).isEqualTo(Optional.of(TITLE));
+        assertThat(checksOutput.getSummary()).isEqualTo(Optional.of(SUMMARY));
+        assertThat(checksOutput.getText()).isEqualTo(Optional.of(TEXT));
         assertThat(checksOutput.getChecksAnnotations())
                 .usingFieldByFieldElementComparator()
                 .containsExactlyInAnyOrderElementsOf(annotations);
@@ -85,10 +84,9 @@ void shouldCopyConstructCorrectly() {
                 .build();
 
         ChecksOutput copied = new ChecksOutput(checksOutput);
-        ChecksOutputAssert.assertThat(copied)
-                .hasTitle(Optional.of(TITLE))
-                .hasSummary(Optional.of(SUMMARY))
-                .hasText(Optional.of(TEXT));
+        assertThat(copied.getTitle()).isEqualTo(Optional.of(TITLE));
+        assertThat(copied.getSummary()).isEqualTo(Optional.of(SUMMARY));
+        assertThat(copied.getText()).isEqualTo(Optional.of(TEXT));
         assertThat(copied.getChecksAnnotations())
                 .usingFieldByFieldElementComparator()
                 .containsExactlyInAnyOrderElementsOf(annotations);
@@ -97,35 +95,6 @@ void shouldCopyConstructCorrectly() {
                 .containsExactlyInAnyOrderElementsOf(images);
     }
 
-    @Test
-    void shouldTruncateTextFromStart() {
-        String longText = "This is the beginning.\n" + "Middle part.\n".repeat(10) + "This is the end.\n";
-        ChecksOutput checksOutput = new ChecksOutputBuilder()
-                .withText(longText)
-                .build();
-
-        String truncated = checksOutput.getText(75).orElse("");
-
-        assertThat(truncated)
-                .startsWith("Output truncated.")
-                .endsWith("This is the end.\n");
-        assertThat(truncated.length()).isLessThanOrEqualTo(75);
-    }
-
-    @Test
-    void shouldNotTruncateShortText() {
-        String shortText = "This is a short text that should not be truncated.";
-        ChecksOutput checksOutput = new ChecksOutputBuilder()
-                .withText(shortText)
-                .build();
-
-        String result = checksOutput.getText(100).orElse("");
-
-        assertThat(result)
-                .isEqualTo(shortText)
-                .doesNotContain("Output truncated.");
-    }
-
     private List<ChecksAnnotation> createAnnotations() {
         final ChecksAnnotationBuilder builder = new ChecksAnnotationBuilder()
                 .withPath("src/main/java/1.java")

src/test/java/io/jenkins/plugins/checks/status/BuildStatusChecksPublisherITest.java

@@ -297,6 +297,61 @@ public void shouldPublishStageDetailsWithoutLogsIfRequested() {
         });
     }
 
+    /**
+     * Test that log messages are properly truncated when they exceed the maximum size limit.
+     */
+    @Test
+    public void shouldTruncateLogsWhenExceedingMaxSize() {
+        getProperties().setApplicable(true);
+        getProperties().setSkipped(false);
+        getProperties().setName("Test Status");
+        getProperties().setSuppressLogs(false);
+        WorkflowJob job = createPipeline();
+
+        // Create a pipeline that generates a large log output
+        job.setDefinition(new CpsFlowDefinition(""
+                + "node {\n"
+                + "  stage('Large Log Stage') {\n"
+                + "    // Generate a large log using Jenkins' built-in commands\n"
+                + "    def logContent = (1..1000).collect { i ->\n"
+                + "      \"Line ${i}: This is a very long log line that will be repeated many times to test truncation. Adding some extra system information here.\"\n"
+                + "    }.join('\\n')\n"
+                + "    // Use writeFile and bat/sh based on platform\n"
+                + "    writeFile file: 'large_log.txt', text: logContent\n"
+                + "    if (isUnix()) {\n"
+                + "      sh 'cat large_log.txt && exit 1'\n"
+                + "    } else {\n"
+                + "      bat 'type large_log.txt && exit /b 1'\n"
+                + "    }\n"
+                + "    error('Pipeline failed with large logs')\n"
+                + "  }\n"
+                + "}", true));
+
+        buildWithResult(job, Result.FAILURE);
+
+        List<ChecksDetails> checksDetails = getFactory().getPublishedChecks();
+
+        // Get the final check details which should contain the truncated logs
+        ChecksDetails details = checksDetails.get(checksDetails.size() - 1);
+        assertThat(details.getStatus()).isEqualTo(ChecksStatus.COMPLETED);
+        assertThat(details.getConclusion()).isEqualTo(ChecksConclusion.FAILURE);
+        assertThat(details.getOutput()).isPresent().get().satisfies(output -> {
+            assertThat(output.getSummary()).isPresent().get().satisfies(summary -> {
+                // Verify the log section exists and is truncated
+                assertThat(summary).contains("<details>");
+                assertThat(summary).contains("</details>");
+                assertThat(summary).contains("Build log");
+                assertThat(summary).contains("Build log truncated.");
+                assertThat(summary).doesNotContain("Line 1:");  // Should be truncated from the start
+                assertThat(summary).contains("exit");  // Should see the exit command at the end
+                // Verify the truncation message appears at the start of the log section
+                assertThat(summary).matches(Pattern.compile(".*<summary>Build log</summary>\\s+\\n```\\s*\\nBuild log truncated.\\n\\n.*", Pattern.DOTALL));
+                // Verify the total size is within limits
+                assertThat(summary.length()).isLessThanOrEqualTo(65_535);
+            });
+        });
+    }
+
     /**
      * Validates that a simple successful pipeline works.
      */