test: add multiline repl input regression test

This commit adds a regression test for
de848ac1e0483327a2ce8716c3f8567eaeacb660, which broke
multiline input in the REPL.

PR-URL: https://github.com/nodejs/node/pull/18718
Refs: https://github.com/nodejs/node/pull/17828
Refs: https://github.com/nodejs/node/pull/18715
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-repl-multiline.js

@@ -0,0 +1,35 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const repl = require('repl');
+const inputStream = new common.ArrayStream();
+const outputStream = new common.ArrayStream();
+const input = ['var foo = {', '};', 'foo;'];
+let output = '';
+
+outputStream.write = (data) => { output += data.replace('\r', ''); };
+
+const r = repl.start({
+  prompt: '',
+  input: inputStream,
+  output: outputStream,
+  terminal: true,
+  useColors: false
+});
+
+r.on('exit', common.mustCall(() => {
+  const actual = output.split('\n');
+
+  // Validate the output, which contains terminal escape codes.
+  assert.strictEqual(actual.length, 6);
+  assert.ok(actual[0].endsWith(input[0]));
+  assert.ok(actual[1].includes('... '));
+  assert.ok(actual[1].endsWith(input[1]));
+  assert.strictEqual(actual[2], 'undefined');
+  assert.ok(actual[3].endsWith(input[2]));
+  assert.strictEqual(actual[4], '{}');
+  // Ignore the last line, which is nothing but escape codes.
+}));
+
+inputStream.run(input);
+r.close();