Keep track of used labels

test/spec/ol/render/canvas/index.test.js

@@ -10,17 +10,6 @@ describe('ol.render.canvas', function() {
   font.rel = 'stylesheet';
   const head = document.getElementsByTagName('head')[0];
 
-  it('pruneLabelCache()', function() {
-    const highWaterMark = render.labelCache.highWaterMark;
-    render.labelCache.highWaterMark = 1;
-    render.labelCache.set('foo', document.createElement('canvas'));
-    render.labelCache.set('bar', document.createElement('canvas'));
-    render.pruneLabelCache();
-    expect(render.labelCache.getCount()).to.be(1);
-    render.labelCache.highWaterMark = highWaterMark;
-    render.labelCache.clear();
-  });
-
   describe('ol.render.canvas.checkFont()', function() {
 
     beforeEach(function() {

test/spec/ol/render/canvas/labelcache.test.js

@@ -0,0 +1,27 @@
+import LabelCache from '../../../../../src/ol/render/canvas/LabelCache';
+
+describe('ol.render.canvas.LabelCache', function() {
+
+  it('#prune()', function() {
+    const labelCache = new LabelCache(1);
+    labelCache.set('key1', document.createElement('canvas'));
+    labelCache.set('key2', document.createElement('canvas'));
+    labelCache.prune();
+    expect(labelCache.getCount()).to.be(1);
+  });
+
+  it('#prune() leaves used labels untouched until consumer is released', function() {
+    const labelCache = new LabelCache(1);
+    labelCache.set('key1', document.createElement('canvas'));
+    labelCache.set('key2', document.createElement('canvas'));
+    const consumer = {};
+    labelCache.get('key1', consumer);
+    labelCache.get('key2', consumer);
+    labelCache.prune();
+    expect(labelCache.getCount()).to.be(2);
+    labelCache.release(consumer);
+    labelCache.prune();
+    expect(labelCache.getCount()).to.be(1);
+  });
+
+});