1 files changed, 43 insertions, 0 deletions
diff --git a/test/parallel/test-icu-stringwidth.js b/test/parallel/test-icu-stringwidth.js
new file mode 100644
index 0000000000..5b66f00c32
--- /dev/null
+++ b/test/parallel/test-icu-stringwidth.js
@@ -0,0 +1,43 @@
+// Flags: --expose_internals
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const readline = require('internal/readline');
+
+if (!process.binding('config').hasIntl) {
+  common.skip('missing intl... skipping test');
+  return;
+}
+
+// Test column width
+assert.strictEqual(readline.getStringWidth('a'), 1);
+assert.strictEqual(readline.getStringWidth('丁'), 2);
+assert.strictEqual(readline.getStringWidth('\ud83d\udc78\ud83c\udfff'), 2);
+assert.strictEqual(readline.getStringWidth('👅'), 2);
+assert.strictEqual(readline.getStringWidth('\n'), 0);
+assert.strictEqual(readline.getStringWidth('\u200Ef\u200F'), 1);
+assert.strictEqual(readline.getStringWidth(97), 1);
+
+// The following is an emoji sequence. In some implementations, it is
+// represented as a single glyph, in other implementations as a sequence
+// of individual glyphs. By default, the algorithm will assume the single
+// glyph interpretation and return a value of 2. By passing the
+// expandEmojiSequence: true option, each component will be counted
+// individually.
+assert.strictEqual(readline.getStringWidth('👩‍👩‍👧‍👧'), 2);
+assert.strictEqual(
+    readline.getStringWidth('👩‍👩‍👧‍👧', {expandEmojiSequence: true}), 8);
+
+// By default, unicode characters whose width is considered ambiguous will
+// be considered half-width. For these characters, getStringWidth will return
+// 1. In some contexts, however, it is more appropriate to consider them full
+// width. By default, the algorithm will assume half width. By passing
+// the ambiguousAsFullWidth: true option, ambiguous characters will be counted
+// as 2 columns.
+assert.strictEqual(readline.getStringWidth('\u01d4'), 1);
+assert.strictEqual(
+    readline.getStringWidth('\u01d4', {ambiguousAsFullWidth: true}), 2);
+
+// Control chars and combining chars are zero
+assert.strictEqual(readline.getStringWidth('\u200E\n\u220A\u20D2'), 1);