Add unit test for extractIntersectingTiles

lib/spatial-index/__tests__/util.js

 import test from 'ava'
-import {featureMatches, bboxMaxLength, sortAndPickResults, computeScore} from '../util.js'
+import {featureMatches, bboxMaxLength, sortAndPickResults, computeScore, extractIntersectingTiles} from '../util.js'
 
 test('featureMatches', t => {
   const feature = {
@@ -95,3 +95,40 @@ test('computeScore', t => {
   t.is(far, 0.9995)
   t.is(near, 0.9999)
 })
+
+test('extractIntersectingTiles', t => {
+  t.deepEqual(extractIntersectingTiles({
+    coordinates: [
+      [
+        [
+          6.146_559_068_778_885,
+          49.155_098_557_172_95
+        ],
+        [
+          6.128_952_349_766_308,
+          49.108_796_765_464_69
+        ],
+        [
+          6.190_071_215_126_494,
+          49.114_375_817_094_98
+        ],
+        [
+          6.183_118_243_287_453,
+          49.146_663_259_683_21
+        ],
+        [
+          6.146_559_068_778_885,
+          49.155_098_557_172_95
+        ]
+      ]
+    ],
+    type: 'Polygon'
+  }).sort(), [
+    '13/4235/2807',
+    '13/4235/2808',
+    '13/4235/2809',
+    '13/4236/2807',
+    '13/4236/2808',
+    '13/4236/2809'
+  ])
+})