Integrated code lifecycle: Fix handling of empty error text nodes in …

…XML result parser (#9204)

src/main/java/de/tum/in/www1/artemis/service/connectors/localci/buildagent/BuildJobExecutionService.java

@@ -356,7 +356,7 @@ private BuildResult parseTestResults(TarArchiveInputStream testResultsTarInputSt
             }
             catch (Exception e) {
                 // Exceptions due to one invalid file should not lead to the whole build to fail.
-                String msg = "Error while parsing report file" + fileName + ", ignoring.";
+                String msg = "Error while parsing report file " + fileName + ", ignoring.";
                 buildLogsMap.appendBuildLogEntry(buildJobId, msg);
                 log.warn(msg, e);
             }

src/main/java/de/tum/in/www1/artemis/service/connectors/localci/buildagent/TestResultXmlParser.java

@@ -106,7 +106,15 @@ static final class Failure {
         private String detailedMessage;
 
         private String extractMessage() {
-            return message != null ? message : detailedMessage;
+            if (message != null) {
+                return message;
+            }
+            else if (detailedMessage != null) {
+                return detailedMessage;
+            }
+            // empty text nodes are deserialized as null instead of a string, see: https://github.com/FasterXML/jackson-dataformat-xml/issues/565
+            // note that this workaround does not fix the issue entirely, as strings of only whitespace become the empty string
+            return "";
         }
 
         @JacksonXmlProperty(isAttribute = true, localName = "message")

src/test/java/de/tum/in/www1/artemis/service/connectors/localci/buildagent/TestResultXmlParserTest.java

@@ -187,4 +187,25 @@ void testOutputInvalidXMLCharacters() throws IOException {
         assertThat(test.getName()).isEqualTo("CompileLinkedList");
         assertThat(test.getTestMessages().getFirst()).isEqualTo("Build for directory ../assignment/build failed. Returncode is 2.");
     }
+
+    @Test
+    void testEmptyTestMessage() throws IOException {
+        String input = """
+                <testsuites>
+                    <testsuite package="mwe-package" id="0" name="mwe-suite-name" timestamp="2024-08-09T12:34:56"
+                    hostname="localhost" tests="1" failures="1" errors="0" time="0">
+                        <properties></properties>
+                            <testcase name="mwe-name" classname="mwe-class" time="0">
+                                <failure type="empty"></failure>
+                        </testcase>
+                    </testsuite>
+                </testsuites>
+                """;
+
+        TestResultXmlParser.processTestResultFile(input, failedTests, successfulTests);
+        assertThat(failedTests).hasSize(1);
+        var test = failedTests.getFirst();
+        assertThat(test.getName()).isEqualTo("mwe-name");
+        assertThat(test.getTestMessages()).hasSize(1).contains("");
+    }
 }