Fix flakey pipe removal (#837)

On posix platforms if a named pipe hasn't been written to then
occasionally calls to fs.lstat (which I believe fs.rm uses internally)
will  hang indefinitely.

If a test run failed due to a compiler error in the build then the pipe
never be written to. By repeatedly trying to perform a test run with
code that fails to compile eventually this hang would appear.

Work around the issue by writing to the pipe if compilation fails,
ensuring the connection opens/closes and the pipe can be removed.

Author: plemarquand

src/TestExplorer/TestParsers/SwiftTestingOutputParser.ts

@@ -23,6 +23,7 @@ import {
 import { ITestRunState } from "./TestRunState";
 import { TestClass } from "../TestDiscovery";
 import { sourceLocationToVSCodeLocation } from "../../utilities/utilities";
+import { exec } from "child_process";
 
 // All events produced by a swift-testing run will be one of these three types.
 // Detailed information about swift-testing's JSON schema is available here:
@@ -149,6 +150,7 @@ export interface SourceLocation {
 export class SwiftTestingOutputParser {
     private completionMap = new Map<number, boolean>();
     private testCaseMap = new Map<string, Map<string, TestCase>>();
+    private path?: string;
 
     constructor(
         public testRunStarted: () => void,
@@ -164,6 +166,8 @@ export class SwiftTestingOutputParser {
         runState: ITestRunState,
         pipeReader?: INamedPipeReader
     ): Promise<void> {
+        this.path = path;
+
         // Creates a reader based on the platform unless being provided in a test context.
         const reader = pipeReader ?? this.createReader(path);
         const readlinePipe = new Readable({
@@ -182,6 +186,18 @@ export class SwiftTestingOutputParser {
         reader.start(readlinePipe);
     }
 
+    public async close() {
+        if (!this.path) {
+            return;
+        }
+
+        return new Promise<void>(resolve => {
+            exec(`echo '{}' > ${this.path}`, () => {
+                resolve();
+            });
+        });
+    }
+
     private createReader(path: string): INamedPipeReader {
         return process.platform === "win32"
             ? new WindowsNamedPipeReader(path)

src/TestExplorer/TestRunner.ts

@@ -508,6 +508,8 @@ export class TestRunner {
             // Test failures result in error code 1
             if (error !== 1) {
                 this.testRun.appendOutput(`\r\nError: ${getErrorDescription(error)}`);
+            } else {
+                this.swiftTestOutputParser.close();
             }
         } finally {
             outputStream.end();