Make zDirection configurable on tile source

test/spec/ol/renderer/canvas/tilelayer.test.js

@@ -86,6 +86,17 @@ describe('ol.renderer.canvas.TileLayer', function() {
         done();
       });
     });
+
+    it('respects the source\'s zDirection setting', function(done) {
+      layer.getSource().zDirection = 1;
+      map.getView().setZoom(5.8); // would lead to z6 tile request with the default zDirection
+      map.once('rendercomplete', function() {
+        const tileCache = layer.getSource().tileCache;
+        const keys = tileCache.getKeys();
+        expect(keys.some(key => key.startsWith('6/'))).to.be(false);
+        done();
+      });
+    });
   });
 
 });

test/spec/ol/renderer/canvas/vectortilelayer.test.js

@@ -101,7 +101,7 @@ describe('ol.renderer.canvas.VectorTileLayer', function() {
     it('creates a new instance', function() {
       const renderer = new CanvasVectorTileLayerRenderer(layer);
       expect(renderer).to.be.a(CanvasVectorTileLayerRenderer);
-      expect(renderer.zDirection).to.be(1);
+      expect(renderer.getLayer()).to.equal(layer);
     });
 
     it('does not render replays for pure image rendering', function() {

test/spec/ol/source/vectortile.test.js

@@ -26,6 +26,10 @@ describe('ol.source.VectorTile', function() {
       expect(source.format_).to.equal(format);
     });
 
+    it('sets the default zDirection on the instance', function() {
+      expect(source.zDirection).to.be(1);
+    });
+
     it('uses ol.VectorTile as default tileClass', function() {
       expect(source.tileClass).to.equal(VectorTile);
     });

test/spec/ol/source/xyz.test.js

@@ -20,6 +20,13 @@ describe('ol.source.XYZ', function() {
       expect(source).to.be.an(TileSource);
     });
 
+    it('can be constructed with a custom zDirection', function() {
+      const source = new XYZ({
+        zDirection: -1
+      });
+      expect(source.zDirection).to.be(-1);
+    });
+
     it('can be constructed with a custom tile grid', function() {
       const tileGrid = createXYZ();
       const tileSource = new XYZ({