Fake hasColors() in worker processes

Fixes #2170.

Author: oantoro

lib/fork.js

@@ -25,6 +25,7 @@ if (process.env.NODE_PATH) {
 
 const describeTTY = tty => ({
 	colorDepth: tty.getColorDepth ? tty.getColorDepth() : undefined,
+	hasColors: typeof tty.hasColors === 'function',
 	columns: tty.columns || 80,
 	rows: tty.rows
 });

lib/worker/fake-tty-has-colors.js

@@ -0,0 +1,19 @@
+'use strict';
+const tty = require('tty');
+
+// Call original method to ensure the correct errors are thrown.
+const assertHasColorsArguments = count => {
+	tty.WriteStream.prototype.hasColors(count);
+};
+
+const makeHasColors = colorDepth => (count = 16, env) => {
+	// `count` is optional too, so make sure it's not an env object.
+	if (env === undefined && typeof count === 'object' && count !== null) {
+		count = 16;
+	}
+
+	assertHasColorsArguments(count);
+	return count <= 2 ** colorDepth;
+};
+
+module.exports = makeHasColors;

lib/worker/fake-tty.js

@@ -2,13 +2,14 @@
 const tty = require('tty');
 const ansiEscapes = require('ansi-escapes');
 const options = require('./options').get();
+const makeHasColors = require('./fake-tty-has-colors');
 
 const fakeTTYs = new Set();
 
 const {isatty} = tty;
 tty.isatty = fd => fakeTTYs.has(fd) || isatty(fd);
 
-const simulateTTY = (stream, {colorDepth, columns, rows}) => {
+const simulateTTY = (stream, {colorDepth, hasColors, columns, rows}) => {
 	Object.assign(stream, {isTTY: true, columns, rows});
 
 	stream.clearLine = dir => {
@@ -35,6 +36,10 @@ const simulateTTY = (stream, {colorDepth, columns, rows}) => {
 	if (colorDepth !== undefined) {
 		stream.getColorDepth = () => colorDepth;
 	}
+
+	if (hasColors) {
+		stream.hasColors = makeHasColors(colorDepth);
+	}
 };
 
 if (options.tty.stderr) {

test/helper/simulate-tty.js

@@ -1,13 +1,18 @@
 'use strict';
+const makeHasColors = require('../../lib/worker/fake-tty-has-colors');
 
-const simulateTTY = (stream, colorDepth) => {
+const simulateTTY = (stream, colorDepth, hasColors) => {
 	stream.isTTY = true;
 	stream.columns = 80;
 	stream.rows = 24;
 
 	if (colorDepth) {
 		stream.getColorDepth = () => colorDepth;
 	}
+
+	if (hasColors) {
+		stream.hasColors = makeHasColors(colorDepth);
+	}
 };
 
 // The execCli helper spawns tests in a child process. This means that stdout is
@@ -17,7 +22,8 @@ if (process.env.AVA_SIMULATE_TTY) {
 	const colorDepth = process.env.AVA_TTY_COLOR_DEPTH ?
 		parseInt(process.env.AVA_TTY_COLOR_DEPTH, 10) :
 		undefined;
+	const hasColors = process.env.AVA_TTY_HAS_COLORS !== undefined;
 
-	simulateTTY(process.stderr, colorDepth);
-	simulateTTY(process.stdout, colorDepth);
+	simulateTTY(process.stderr, colorDepth, hasColors);
+	simulateTTY(process.stdout, colorDepth, hasColors);
 }

test/integration/node-assertions.js

@@ -8,7 +8,8 @@ test('node assertion failures are reported to the console when running in a term
 		dirname: 'fixture/node-assertions',
 		env: {
 			AVA_SIMULATE_TTY: true,
-			AVA_TTY_COLOR_DEPTH: 8
+			AVA_TTY_COLOR_DEPTH: 8,
+			AVA_TTY_HAS_COLORS: typeof process.stderr.hasColors === 'function'
 		}
 	};