test: add regression test for 13557

Fixes: #13557
PR-URL: #13560
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>

Author: addaleax

test/parallel/test-readline-reopen.js

@@ -0,0 +1,44 @@
+'use strict';
+
+// Regression test for https://github.com/nodejs/node/issues/13557
+// Tests that multiple subsequent readline instances can re-use an input stream.
+
+const common = require('../common');
+const assert = require('assert');
+const readline = require('readline');
+const { PassThrough } = require('stream');
+
+const input = new PassThrough();
+const output = new PassThrough();
+
+const rl1 = readline.createInterface({
+  input,
+  output,
+  terminal: true
+});
+
+rl1.on('line', common.mustCall(rl1OnLine));
+
+// Write a line plus the first byte of a UTF-8 multibyte character to make sure
+// that it doesn’t get lost when closing the readline instance.
+input.write(Buffer.concat([
+  Buffer.from('foo\n'),
+  Buffer.from([ 0xe2 ])  // Exactly one third of a ☃ snowman.
+]));
+
+function rl1OnLine(line) {
+  assert.strictEqual(line, 'foo');
+  rl1.close();
+  const rl2 = readline.createInterface({
+    input,
+    output,
+    terminal: true
+  });
+
+  rl2.on('line', common.mustCall((line) => {
+    assert.strictEqual(line, '☃bar');
+    rl2.close();
+  }));
+  input.write(Buffer.from([0x98, 0x83])); // The rest of the ☃ snowman.
+  input.write('bar\n');
+}