feat(custom_layer_sorting): sorting for unknown layers fix to ensure …

…stable sorting order

index.js

@@ -161,8 +161,12 @@ const fallbacks = [
   { either: isSmallLocality, resolve: resolveSmallLocality },
   { either: isSmallLocaladmin, resolve: resolveSmallLocaladmin },
   { either: isNonPopularNeighbourhood, resolve: resolveNonPopularNeighbourhood },
-  // the 'else' case, always returns true
-  { either: _.constant(true), resolve: (result1, result2) => { return result1 < result2; } }
+  // the 'else' case, always sort by score, avoiding returning 0 because js sort is unstable
+  { either: _.constant(true), resolve: (result1, result2) => {
+    if( isNaN( result1._score ) || isNaN( result2._score ) ){ return -1; }
+    if( result1._score === result2._score ){ return -1; }
+    return result1._score > result2._score ? -1 : 1;
+  }}
 ];
 
 module.exports = (clean) => {

test/index.js

@@ -342,4 +342,21 @@ tape('neighbourhood', (test) => {
 
   });
 
+  test.test('custom layers should be sorted by score', t => {
+    const sorter = require('../index')({});
+
+    const result_one = new ResultBuilder('stops').score(27.178297).build();
+    const result_two = new ResultBuilder('stops').score(1.4754213).build();
+    const result_three = new ResultBuilder('stops').score(1.4754213).build();
+
+    t.equals(sorter(result_one, result_two), -1);
+    t.equals(sorter(result_two, result_one), +1);
+    t.equals(sorter(result_two, result_three), -1);
+    t.equals(sorter(result_three, result_two), -1);
+    t.equals(sorter(result_one, result_three), -1);
+    t.equals(sorter(result_three, result_one), +1);
+    t.end();
+
+  });
+
 });