Don't highlight formatted values with --no-color

Fixes #843
(#843 (comment)). Values
shouldn't be highlighted during formatting if colors are disabled.

lib/format-assert-error.js

@@ -5,12 +5,13 @@ const chalk = require('chalk');
 const diff = require('diff');
 const DiffMatchPatch = require('diff-match-patch');
 const indentString = require('indent-string');
+const globals = require('./globals');
 
 function formatValue(value, options) {
 	return prettyFormat(value, Object.assign({
 		callToJSON: false,
 		plugins: [reactTestPlugin],
-		highlight: true
+		highlight: globals.options.color !== false
 	}, options));
 }
 exports.formatValue = formatValue;

test/cli.js

@@ -11,6 +11,7 @@ const proxyquire = require('proxyquire');
 const sinon = require('sinon');
 const uniqueTempDir = require('unique-temp-dir');
 const execa = require('execa');
+const stripAnsi = require('strip-ansi');
 
 const cliPath = path.join(__dirname, '../cli.js');
 
@@ -525,3 +526,19 @@ test('snapshots work', t => {
 		});
 	});
 });
+
+test('--no-color disables formatting colors', t => {
+	execCli(['--no-color', '--verbose', 'formatting-color.js'], {dirname: 'fixture'}, (err, stdout, stderr) => {
+		t.ok(err);
+		t.is(stripAnsi(stderr), stderr);
+		t.end();
+	});
+});
+
+test('--color enables formatting colors', t => {
+	execCli(['--color', '--verbose', 'formatting-color.js'], {dirname: 'fixture'}, (err, stdout, stderr) => {
+		t.ok(err);
+		t.isNot(stripAnsi(stderr), stderr);
+		t.end();
+	});
+});

test/fixture/formatting-color.js

@@ -0,0 +1,5 @@
+import test from '../..';
+
+test(t => {
+	t.deepEqual({foo: 1}, {foo: 2});
+});