test: assert diff no color

PR-URL: https://github.com/nodejs/node/pull/24181
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/pseudo-tty/test-assert-no-color.js

@@ -0,0 +1,19 @@
+'use strict';
+require('../common');
+const assert = require('assert').strict;
+
+process.env.NODE_DISABLE_COLORS = true;
+
+try {
+  assert.deepStrictEqual({}, { foo: 'bar' });
+} catch (error) {
+  const expected =
+    'Expected values to be strictly deep-equal:\n' +
+    '+ actual - expected\n' +
+    '\n' +
+    '+ {}\n' +
+    '- {\n' +
+    '-   foo: \'bar\'\n' +
+    '- }';
+  assert.strictEqual(error.message, expected);
+}