diff --git a/test/node/ol/array.test.js b/test/node/ol/array.test.js
index 12bcc24bb4..fe5db08b19 100644
--- a/test/node/ol/array.test.js
+++ b/test/node/ol/array.test.js
@@ -475,34 +475,94 @@ describe('ol/array.js', function () {
       expect(linearFindNearest(arr, 1000, 1)).to.eql(0);
       expect(linearFindNearest(arr, 1000, -1)).to.eql(0);
 
+      expect(linearFindNearest(arr, 999, -1)).to.eql(1);
+
+      expect(
+        linearFindNearest(arr, 901, function (value, high, low) {
+          return value - (low + (high - low) * 0.8);
+        })
+      ).to.eql(0);
+
+      expect(
+        linearFindNearest(arr, 900, function (value, high, low) {
+          return value - (low + (high - low) * 0.8);
+        })
+      ).to.eql(1);
+
       expect(linearFindNearest(arr, 900, 0)).to.eql(0);
       expect(linearFindNearest(arr, 900, 1)).to.eql(0);
       expect(linearFindNearest(arr, 900, -1)).to.eql(1);
 
+      expect(linearFindNearest(arr, 751, 0)).to.eql(0);
+
       expect(linearFindNearest(arr, 750, 0)).to.eql(1);
       expect(linearFindNearest(arr, 750, 1)).to.eql(0);
       expect(linearFindNearest(arr, 750, -1)).to.eql(1);
 
+      expect(
+        linearFindNearest(arr, 551, function (value, high, low) {
+          return value - (low + (high - low) * 0.1);
+        })
+      ).to.eql(0);
+
+      expect(
+        linearFindNearest(arr, 550, function (value, high, low) {
+          return value - (low + (high - low) * 0.1);
+        })
+      ).to.eql(1);
+
       expect(linearFindNearest(arr, 550, 0)).to.eql(1);
       expect(linearFindNearest(arr, 550, 1)).to.eql(0);
       expect(linearFindNearest(arr, 550, -1)).to.eql(1);
 
+      expect(linearFindNearest(arr, 501, 1)).to.eql(0);
+
       expect(linearFindNearest(arr, 500, 0)).to.eql(1);
       expect(linearFindNearest(arr, 500, 1)).to.eql(1);
       expect(linearFindNearest(arr, 500, -1)).to.eql(1);
 
+      expect(linearFindNearest(arr, 499, -1)).to.eql(2);
+
+      expect(
+        linearFindNearest(arr, 451, function (value, high, low) {
+          return value - (low + (high - low) * 0.875);
+        })
+      ).to.eql(1);
+
+      expect(
+        linearFindNearest(arr, 450, function (value, high, low) {
+          return value - (low + (high - low) * 0.875);
+        })
+      ).to.eql(2);
+
       expect(linearFindNearest(arr, 450, 0)).to.eql(1);
       expect(linearFindNearest(arr, 450, 1)).to.eql(1);
       expect(linearFindNearest(arr, 450, -1)).to.eql(2);
 
+      expect(linearFindNearest(arr, 301, 0)).to.eql(1);
+
       expect(linearFindNearest(arr, 300, 0)).to.eql(2);
       expect(linearFindNearest(arr, 300, 1)).to.eql(1);
       expect(linearFindNearest(arr, 300, -1)).to.eql(2);
 
+      expect(
+        linearFindNearest(arr, 201, function (value, high, low) {
+          return value - (low + (high - low) * 0.25);
+        })
+      ).to.eql(1);
+
+      expect(
+        linearFindNearest(arr, 200, function (value, high, low) {
+          return value - (low + (high - low) * 0.25);
+        })
+      ).to.eql(2);
+
       expect(linearFindNearest(arr, 200, 0)).to.eql(2);
       expect(linearFindNearest(arr, 200, 1)).to.eql(1);
       expect(linearFindNearest(arr, 200, -1)).to.eql(2);
 
+      expect(linearFindNearest(arr, 101, 1)).to.eql(1);
+
       expect(linearFindNearest(arr, 100, 0)).to.eql(2);
       expect(linearFindNearest(arr, 100, 1)).to.eql(2);
       expect(linearFindNearest(arr, 100, -1)).to.eql(2);
diff --git a/test/node/ol/tilegrid/TileGrid.test.js b/test/node/ol/tilegrid/TileGrid.test.js
index a3cfb3c816..4f3e9d0d82 100644
--- a/test/node/ol/tilegrid/TileGrid.test.js
+++ b/test/node/ol/tilegrid/TileGrid.test.js
@@ -1177,6 +1177,64 @@ describe('ol/tilegrid/TileGrid.js', function () {
     });
   });
 
+  describe('getZForResolution (NearestDirectionFunction)', function () {
+    it('returns the expected z value', function () {
+      const tileGrid = new TileGrid({
+        resolutions: resolutions,
+        origin: origin,
+        tileSize: tileSize,
+      });
+
+      expect(
+        tileGrid.getZForResolution(626, function (value, high, low) {
+          return value - (low + (high - low) * 0.25);
+        })
+      ).to.eql(0);
+
+      expect(
+        tileGrid.getZForResolution(625, function (value, high, low) {
+          return value - (low + (high - low) * 0.25);
+        })
+      ).to.eql(1);
+
+      expect(
+        tileGrid.getZForResolution(476, function (value, high, low) {
+          return value - (low + (high - low) * 0.9);
+        })
+      ).to.eql(1);
+
+      expect(
+        tileGrid.getZForResolution(475, function (value, high, low) {
+          return value - (low + (high - low) * 0.9);
+        })
+      ).to.eql(2);
+
+      expect(
+        tileGrid.getZForResolution(201, function (value, high, low) {
+          return value - (low + (high - low) * 0.666666667);
+        })
+      ).to.eql(2);
+
+      expect(
+        tileGrid.getZForResolution(200, function (value, high, low) {
+          return value - (low + (high - low) * 0.666666667);
+        })
+      ).to.eql(3);
+
+      expect(
+        tileGrid.getZForResolution(126, function (value, high, low) {
+          return value - (low + (high - low) * 0.166666667);
+        })
+      ).to.eql(2);
+
+      expect(
+        tileGrid.getZForResolution(125, function (value, high, low) {
+          return value - (low + (high - low) * 0.166666667);
+        })
+      ).to.eql(3);
+    });
+  });
+
   describe('getTileRangeForTileCoordAndZ()', function () {
     const tileGrid = createForExtent(
       getProjection('EPSG:3857').getExtent(),