feat(unicode): ensure 140 char text limit is unicode aware

Author: missinglink

helper/unicode.js

@@ -1,5 +1,6 @@
 const _ = require('lodash');
 const regenerate = require('regenerate');
+const unicodeToArray = require('lodash/_unicodeToArray');
 
 // non-printable control characters
 // ref: https://en.wikipedia.org/wiki/List_of_Unicode_characters
@@ -94,3 +95,31 @@ function normalize(str) {
 }
 
 module.exports.normalize = normalize;
+
+// unicode aware string length function
+// note: ported from 'npm stringz' using 'lodash' internals in place of 'char-regex'
+module.exports.length = (str) => {
+
+  // sanity checking
+  if (!_.isString(str)) { throw new Error('invalid string'); }
+
+  // return count of unicode characters
+  return unicodeToArray(str).length;
+};
+
+// unicode aware substring function
+// note: ported from 'npm stringz' using 'lodash' internals in place of 'char-regex'
+module.exports.substring = (str, begin, end) => {
+
+  // sanity checking
+  if (!_.isString(str)) { throw new Error('invalid string'); }
+
+  // Even though negative numbers work here, theyre not in the spec
+  if (!_.isFinite(begin) || begin < 0) { begin = 0; }
+  if (_.isFinite(end) && end < 0) { end = 0; }
+
+  const chars = unicodeToArray(str);
+  if (chars.length === 0){ return ''; }
+
+  return chars.slice(begin, end).join('');
+};

sanitizer/_text.js

@@ -21,9 +21,9 @@ function _sanitize( raw, clean ){
   if( !_.isString(text) || _.isEmpty(text) ){
     messages.errors.push(`invalid param 'text': text length, must be >0`);
   } else {
-    if( text.length > MAX_TEXT_LENGTH ){
+    if( unicode.length(text) > MAX_TEXT_LENGTH ){
       messages.warnings.push(`param 'text' truncated to ${MAX_TEXT_LENGTH} characters`);
-      text = text.substring(0, MAX_TEXT_LENGTH);
+      text = unicode.substring(text, 0, MAX_TEXT_LENGTH);
     }
     clean.text = text;
   }

test/unit/sanitizer/_text.js

@@ -1,4 +1,5 @@
 const sanitizer = require('../../../sanitizer/_text')();
+const unicode = require('../../../helper/unicode');
 
 module.exports.tests = {};
 
@@ -154,6 +155,19 @@ it again and again until we reach our destination.` };
     t.deepEquals(messages.warnings, [`param 'text' truncated to 140 characters`]);
     t.end();
   });
+
+  // https://github.com/pelias/api/issues/1574
+  test('truncate should be unicode aware', (t) => {
+    const raw = { text: 'a' + '👩‍❤️‍👩'.repeat(200) };
+    const clean = {};
+    const messages = sanitizer.sanitize(raw, clean);
+
+    t.equals(unicode.length(clean.text), 140);
+    t.equals(clean.text, 'a' + '👩‍❤️‍👩'.repeat(139));
+    t.deepEquals(messages.errors, [], 'no errors');
+    t.deepEquals(messages.warnings, [`param 'text' truncated to 140 characters`]);
+    t.end();
+  });
 };
 
 module.exports.all = (tape, common) => {