Temporarily uncork report stream when clearing spinner

The spinner is not cleared while the stream is corked, which then
corrupts the printing of stdout / stderr chunks received from the test
processes.

Fixes #2541

lib/reporters/default.js

@@ -18,7 +18,6 @@ const colors = require('./colors');
 const formatSerializedError = require('./format-serialized-error');
 const improperUsageMessages = require('./improper-usage-messages');
 const prefixTitle = require('./prefix-title');
-const whileCorked = require('./while-corked');
 
 const nodeInternals = require('stack-utils').nodeInternals();
 
@@ -97,6 +96,48 @@ class LineWriterWithSpinner extends LineWriter {
 	}
 }
 
+function manageCorking(stream) {
+	let corked = false;
+	const cork = () => {
+		corked = true;
+		stream.cork();
+	};
+
+	const uncork = () => {
+		corked = false;
+		stream.uncork();
+	};
+
+	return {
+		decorateFlushingWriter(fn) {
+			return function (...args) {
+				if (corked) {
+					stream.uncork();
+				}
+
+				try {
+					return fn.apply(this, args);
+				} finally {
+					if (corked) {
+						stream.cork();
+					}
+				}
+			};
+		},
+
+		decorateWriter(fn) {
+			return function (...args) {
+				cork();
+				try {
+					return fn.apply(this, args);
+				} finally {
+					uncork();
+				}
+			};
+		}
+	};
+}
+
 class Reporter {
 	constructor({
 		verbose,
@@ -112,13 +153,16 @@ class Reporter {
 		this.stdStream = stdStream;
 		this.watching = watching;
 		this.relativeFile = file => path.relative(projectDir, file);
-		this.consumeStateChange = whileCorked(this.reportStream, this.consumeStateChange);
+
+		const {decorateWriter, decorateFlushingWriter} = manageCorking(this.reportStream);
+		this.consumeStateChange = decorateWriter(this.consumeStateChange);
+		this.endRun = decorateWriter(this.endRun);
 
 		if (this.verbose) {
 			this.durationThreshold = durationThreshold || 100;
 			this.spinner = null;
+			this.clearSpinner = () => {};
 			this.lineWriter = new LineWriter(this.reportStream);
-			this.endRun = whileCorked(this.reportStream, this.endRun);
 		} else {
 			this.spinner = ora({
 				isEnabled: true,
@@ -128,8 +172,8 @@ class Reporter {
 				spinner: spinner || (process.platform === 'win32' ? 'line' : 'dots'),
 				stream: reportStream
 			});
+			this.clearSpinner = decorateFlushingWriter(this.spinner.clear.bind(this.spinner));
 			this.lineWriter = new LineWriterWithSpinner(this.reportStream, this.spinner);
-			this.endRun = whileCorked(this.reportStream, whileCorked(this.lineWriter, this.endRun));
 		}
 
 		this.reset();
@@ -362,9 +406,7 @@ class Reporter {
 
 			case 'worker-stderr': {
 				// Forcibly clear the spinner, writing the chunk corrupts the TTY.
-				if (this.spinner !== null) {
-					this.spinner.clear();
-				}
+				this.clearSpinner();
 
 				this.stdStream.write(event.chunk);
 				// If the chunk does not end with a linebreak, *forcibly* write one to
@@ -386,9 +428,7 @@ class Reporter {
 
 			case 'worker-stdout': {
 				// Forcibly clear the spinner, writing the chunk corrupts the TTY.
-				if (this.spinner !== null) {
-					this.spinner.clear();
-				}
+				this.clearSpinner();
 
 				this.stdStream.write(event.chunk);
 				// If the chunk does not end with a linebreak, *forcibly* write one to