fix: do not echo RemoteTestRunner control frames to test output

src/runners/junitRunner/JUnitRunnerResultAnalyzer.ts

@@ -13,6 +13,24 @@ import { IRunTestContext, TestKind, TestLevel, TestResultState } from '../../jav
 
 export class JUnitRunnerResultAnalyzer extends RunnerResultAnalyzer {
 
+    private static readonly CONTROL_MESSAGE_PREFIXES: string[] = [
+        '%TSTTREE',
+        '%TESTS',
+        '%TESTE',
+        '%FAILED',
+        '%ERROR',
+        '%EXPECTS',
+        '%EXPECTE',
+        '%ACTUALS',
+        '%ACTUALE',
+        '%TRACES',
+        '%TRACEE',
+        '%TESTC',
+        '%RUNTIME',
+        '%MENTER',
+        '%MEXIT',
+    ];
+
     private testOutputMapping: Map<string, ITestInfo> = new Map();
     private triggeredTestsMapping: Map<string, TestItem> = new Map();
     private projectName: string;
@@ -25,9 +43,9 @@ export class JUnitRunnerResultAnalyzer extends RunnerResultAnalyzer {
     private tracingItem: TestItem | undefined;
     private traces: MarkdownString;
     private assertionFailure: TestMessage | undefined;
-    private recordingType: RecordingType;
-    private expectString: string;
-    private actualString: string;
+    private recordingType: RecordingType = RecordingType.None;
+    private expectString: string = '';
+    private actualString: string = '';
 
     constructor(protected testContext: IRunTestContext) {
         super(testContext);
@@ -51,12 +69,34 @@ export class JUnitRunnerResultAnalyzer extends RunnerResultAnalyzer {
 
     public analyzeData(data: string): void {
         const lines: string[] = data.split(/\r?\n/);
-        for (const line of lines) {
+        const endsWithNewLine: boolean = /\r?\n$/.test(data);
+        for (let i: number = 0; i < lines.length; i++) {
+            const line: string = lines[i];
+            if (i === lines.length - 1 && endsWithNewLine && line === '') {
+                continue;
+            }
             this.processData(line);
-            this.testContext.testRun.appendOutput(line + '\r\n');
+            // Hide Eclipse RemoteTestRunner protocol frames/payload already consumed by processData().
+            // Forward everything else, including stdout/stderr if present in the runner stream.
+            if (!this.isControlMessage(line) && !this.isRecordingProtocolPayload()) {
+                this.testContext.testRun.appendOutput(line + '\r\n');
+            }
         }
     }
 
+    /**
+     * Whether the given line is an Eclipse RemoteTestRunner control message.
+     * Only known protocol frame prefixes are filtered so user output that merely starts
+     * with '%' (for example, "%OK" or "%STATUS 200") remains visible.
+     */
+    private isControlMessage(line: string): boolean {
+        return JUnitRunnerResultAnalyzer.CONTROL_MESSAGE_PREFIXES.some((prefix: string) => line.startsWith(prefix));
+    }
+
+    private isRecordingProtocolPayload(): boolean {
+        return this.recordingType !== RecordingType.None;
+    }
+
     public processData(data: string): void {
         if (data.startsWith(MessageId.TestTree)) {
             this.enlistToTestMapping(data.substring(MessageId.TestTree.length).trim());

test/suite/JUnitAnalyzer.test.ts

@@ -70,7 +70,7 @@ at org.junit.Assert.assertTrue(Assert.java:53)
 at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)
 %TRACEE 
 %TESTE  1,shouldFail(junit4.TestAnnotation)
-%RUNTIME20;`;
+%RUNTIME20\n`;
         const runnerContext: IRunTestContext = {
             isDebug: false,
             kind: TestKind.JUnit,
@@ -89,6 +89,75 @@ at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)
         assert.ok((testMessage.message as MarkdownString).value.includes('junit4.TestAnnotation.shouldFail([TestAnnotation.java:15](command:_java.test.openStackTrace?%5B%22at%20junit4.TestAnnotation.shouldFail(TestAnnotation.java%3A15)%22%2C%22junit%22%5D))'));
     });
 
+    test("control protocol frames should not be echoed to the output", () => {
+        const testItem = generateTestItem(testController, 'junit@junit4.TestAnnotation#shouldFail', TestKind.JUnit);
+        const testRunRequest = new TestRunRequest([testItem], []);
+        const testRun = testController.createTestRun(testRunRequest);
+        const appendOutputSpy = sinon.spy(testRun, 'appendOutput');
+        const testRunnerOutput = `%TESTC  1 v2
+%TSTTREE1,shouldFail(junit4.TestAnnotation),false,1,false,-1,shouldFail(junit4.TestAnnotation),,
+%TESTS  1,shouldFail(junit4.TestAnnotation)
+Hello from System.out
+%OK
+%ABC
+%STATUS 200
+%FAILED 1,shouldFail(junit4.TestAnnotation)
+%EXPECTS
+expected
+%EXPECTE
+%ACTUALS
+actual
+%ACTUALE
+%TRACES
+java.lang.AssertionError
+at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)
+%TRACEE
+%TESTE  1,shouldFail(junit4.TestAnnotation)
+%RUNTIME20\n`;
+        const runnerContext: IRunTestContext = {
+            isDebug: false,
+            kind: TestKind.JUnit,
+            projectName: 'junit',
+            testItems: [testItem],
+            testRun: testRun,
+            workspaceFolder: workspace.workspaceFolders?.[0]!,
+        };
+
+        const analyzer = new JUnitRunnerResultAnalyzer(runnerContext);
+        analyzer.analyzeData(testRunnerOutput);
+
+        const echoed: string[] = appendOutputSpy.getCalls().map((call) => call.args[0] as string);
+        const echoedLines: string[] = echoed.map((output) => output.replace(/\r?\n$/, ''));
+
+        const controlFrames: string[] = [
+            '%TESTC  1 v2',
+            '%TSTTREE1,shouldFail(junit4.TestAnnotation),false,1,false,-1,shouldFail(junit4.TestAnnotation),,',
+            '%TESTS  1,shouldFail(junit4.TestAnnotation)',
+            '%FAILED 1,shouldFail(junit4.TestAnnotation)',
+            '%EXPECTS',
+            '%EXPECTE',
+            '%ACTUALS',
+            '%ACTUALE',
+            '%TRACES',
+            '%TRACEE',
+            '%TESTE  1,shouldFail(junit4.TestAnnotation)',
+            '%RUNTIME20',
+        ];
+        for (const frame of controlFrames) {
+            assert.ok(!echoedLines.includes(frame), `Control frame leaked to output: ${frame}`);
+        }
+        // Genuine program output should still be forwarded.
+        assert.ok(echoedLines.includes('Hello from System.out'), 'Program output was dropped');
+        assert.ok(echoedLines.includes('%OK'), 'Percent-prefixed program output was dropped');
+        assert.ok(echoedLines.includes('%ABC'), 'Percent-prefixed program output was dropped');
+        assert.ok(echoedLines.includes('%STATUS 200'), 'Percent-prefixed program output was dropped');
+        assert.ok(!echoedLines.includes('expected'), 'Expected-value protocol payload leaked to output');
+        assert.ok(!echoedLines.includes('actual'), 'Actual-value protocol payload leaked to output');
+        assert.ok(!echoedLines.includes('java.lang.AssertionError'), 'Trace protocol payload leaked to output');
+        assert.ok(!echoedLines.includes('at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)'), 'Trace protocol payload leaked to output');
+        assert.notStrictEqual(echoedLines[echoedLines.length - 1], '', 'Trailing newline produced a blank output line');
+    });
+
     test("test stacktrace should be simplified", () => {
         const testItem = generateTestItem(testController, 'junit@App#name', TestKind.JUnit);
         const testRunRequest = new TestRunRequest([testItem], []);