fix: skip trailing empty runner output

Author: wenytang-ms

src/runners/junitRunner/JUnitRunnerResultAnalyzer.ts

@@ -54,7 +54,12 @@ 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);
             // Hide Eclipse RemoteTestRunner protocol frames already consumed by processData().
             // Forward everything else, including stdout/stderr and trace payload lines.

test/suite/JUnitAnalyzer.test.ts

@@ -70,7 +70,8 @@ at org.junit.Assert.assertTrue(Assert.java:53)
 at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)
 %TRACEE 
 %TESTE  1,shouldFail(junit4.TestAnnotation)
-%RUNTIME20`;
+%RUNTIME20
+`;
         const runnerContext: IRunTestContext = {
             isDebug: false,
             kind: TestKind.JUnit,
@@ -150,6 +151,7 @@ at junit4.TestAnnotation.shouldFail(TestAnnotation.java:15)
         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('java.lang.AssertionError'), 'Stack trace content was dropped');
+        assert.ok(!echoedLines.includes(''), 'Trailing newline produced a blank output line');
     });
 
     test("test stacktrace should be simplified", () => {