Programming exercises: Fix an issue when parsing empty files (#8964)

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

@@ -344,7 +344,14 @@ private BuildResult parseTestResults(TarArchiveInputStream testResultsTarInputSt
                 else {
                     // ugly workaround because in swift result files \n\t breaks the parsing
                     var testResultFileString = xmlString.replace("\n\t", "");
-                    processTestResultFile(testResultFileString, failedTests, successfulTests);
+                    if (!testResultFileString.isBlank()) {
+                        processTestResultFile(testResultFileString, failedTests, successfulTests);
+                    }
+                    else {
+                        String msg = "The file " + fileName + " does not contain any testcases.";
+                        buildLogsMap.appendBuildLogEntry(buildJobId, msg);
+                        log.warn(msg);
+                    }
                 }
             }
             catch (IllegalStateException e) {

src/test/java/de/tum/in/www1/artemis/AbstractSpringIntegrationLocalCILocalVCTest.java

@@ -140,6 +140,8 @@ public abstract class AbstractSpringIntegrationLocalCILocalVCTest extends Abstra
 
     protected static final Path OLD_REPORT_FORMAT_TEST_RESULTS_PATH = GRADLE_TEST_RESULTS_PATH.resolve("old-report-format");
 
+    protected static final Path EMPTY_TEST_RESULTS_PATH = GRADLE_TEST_RESULTS_PATH.resolve("empty");
+
     private static final Path SCA_REPORTS_PATH = Path.of("src", "test", "resources", "test-data", "static-code-analysis", "reports");
 
     protected static final Path SPOTBUGS_RESULTS_PATH = SCA_REPORTS_PATH.resolve("spotbugsXml.xml");

src/test/java/de/tum/in/www1/artemis/localvcci/LocalCIIntegrationTest.java

@@ -379,6 +379,25 @@ void testStaticCodeAnalysis() throws IOException {
         localVCLocalCITestService.testLatestSubmission(studentParticipation.getId(), commitHash, 1, false, true, 15, null);
     }
 
+    @Test
+    @WithMockUser(username = TEST_PREFIX + "student1", roles = "USER")
+    void testEmptyResultFile() throws Exception {
+        ProgrammingExerciseStudentParticipation studentParticipation = localVCLocalCITestService.createParticipation(programmingExercise, student1Login);
+
+        localVCLocalCITestService.mockTestResults(dockerClient, EMPTY_TEST_RESULTS_PATH, LOCALCI_WORKING_DIRECTORY + LOCALCI_RESULTS_DIRECTORY);
+        localVCServletService.processNewPush(commitHash, studentAssignmentRepository.originGit.getRepository());
+        localVCLocalCITestService.testLatestSubmission(studentParticipation.getId(), commitHash, 0, true);
+
+        studentParticipation = programmingExerciseStudentParticipationRepository
+                .findByIdWithLatestResultAndFeedbacksAndRelatedSubmissions(studentParticipation.getId(), ZonedDateTime.now()).orElseThrow();
+        var result = studentParticipation.getResults().iterator().next();
+
+        var buildLogs = buildLogEntryService.getLatestBuildLogs((ProgrammingSubmission) result.getSubmission());
+
+        assertThat(buildLogs).isNotEmpty().anyMatch(log -> log.getLog().equals("The file results.xml does not contain any testcases.\n"))
+                .noneMatch(log -> log.getLog().contains("Exception"));
+    }
+
     @Test
     @WithMockUser(username = TEST_PREFIX + "student1", roles = "USER")
     void testBuildLogs() throws IOException {