readline: allow history to be disabled

1.  The `historySize` to default to `30` only if `undefined`.
2.  If `historySize` is set to 0, then disable caching the line.
3.  Added unit tests.
4.  Updated documentation.

Fixes: https://github.com/nodejs/node/issues/6336
PR-URL: https://github.com/nodejs/node/pull/6352
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/test/parallel/test-readline-interface.js b/test/parallel/test-readline-interface.js
index 02f6dc980a..ab0c6d8824 100644
--- a/test/parallel/test-readline-interface.js
+++ b/test/parallel/test-readline-interface.js
@@ -27,6 +27,25 @@ function isWarned(emitter) {
   var rli;
   var called;
 
+  // disable history
+  fi = new FakeInput();
+  rli = new readline.Interface({ input: fi, output: fi, terminal: terminal,
+                              historySize: 0 });
+  assert.strictEqual(rli.historySize, 0);
+
+  fi.emit('data', 'asdf\n');
+  assert.deepStrictEqual(rli.history, terminal ? [] : undefined);
+  rli.close();
+
+  // default history size 30
+  fi = new FakeInput();
+  rli = new readline.Interface({ input: fi, output: fi, terminal: terminal});
+  assert.strictEqual(rli.historySize, 30);
+
+  fi.emit('data', 'asdf\n');
+  assert.deepStrictEqual(rli.history, terminal ? ['asdf'] : undefined);
+  rli.close();
+
   // sending a full line
   fi = new FakeInput();
   rli = new readline.Interface({ input: fi, output: fi, terminal: terminal });