diff --git a/src/ol/assertionerror.js b/src/ol/assertionerror.js
new file mode 100644
index 0000000000..cc3c723885
--- /dev/null
+++ b/src/ol/assertionerror.js
@@ -0,0 +1,36 @@
+goog.provide('ol.AssertionError');
+
+goog.require('ol');
+
+/**
+ * Error object thrown when an assertion failed. This is an ECMA-262 Error,
+ * extended with a `code` property.
+ * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error}
+ * @constructor
+ * @extends {Error}
+ * @implements {oli.AssertionError}
+ * @param {number} code Error code.
+ */
+ol.AssertionError = function(code) {
+
+  /**
+   * @type {string}
+   */
+  this.message = 'Assertion failed. See ' +
+      (ol.VERSION ? 'http://openlayers.org/en/' + ol.VERSION.split('-')[0] : '') +
+      '/doc/errors/#' + code + ' for details.';
+
+  /**
+   * Error code. The meaning of the code can be found on
+   * {@link http://openlayers.org/en/latest/errors.html} (replace `latest` with
+   * the version found in the OpenLayers script's header comment if a version
+   * other than the latest is used).
+   * @type {number}
+   * @api
+   */
+  this.code = code;
+
+  this.name = 'AssertionError';
+
+};
+ol.inherits(ol.AssertionError, Error);
diff --git a/src/ol/asserts.js b/src/ol/asserts.js
new file mode 100644
index 0000000000..d9cf9c2339
--- /dev/null
+++ b/src/ol/asserts.js
@@ -0,0 +1,15 @@
+goog.provide('ol.asserts');
+
+goog.require('ol');
+goog.require('ol.AssertionError');
+
+
+/**
+ * @param {*} assertion Assertion we expected to be truthy.
+ * @param {number} errorCode Error code.
+ */
+ol.asserts.assert = function(assertion, errorCode) {
+  if (!assertion) {
+    throw new ol.AssertionError(errorCode);
+  }
+};
diff --git a/src/ol/color.js b/src/ol/color.js
index 178bca7521..69a39c4bef 100644
--- a/src/ol/color.js
+++ b/src/ol/color.js
@@ -159,7 +159,7 @@ ol.color.fromStringInternal_ = function(s) {
 
   if (ol.color.hexColorRe_.exec(s)) { // hex
     var n = s.length - 1; // number of hex digits
-    ol.assert(n == 3 || n == 6, 54); // Hex color should have 3 or 6 digits
+    ol.asserts.assert(n == 3 || n == 6, 54); // Hex color should have 3 or 6 digits
     var d = n == 3 ? 1 : 2; // number of digits per channel
     r = parseInt(s.substr(1 + 0 * d, d), 16);
     g = parseInt(s.substr(1 + 1 * d, d), 16);
@@ -183,7 +183,7 @@ ol.color.fromStringInternal_ = function(s) {
     b = Number(match[3]);
     color = ol.color.normalize([r, g, b, 1]);
   } else {
-    ol.assert(false, 14); // Invalid color
+    ol.asserts.assert(false, 14); // Invalid color
   }
   return /** @type {ol.Color} */ (color);
 };
diff --git a/src/ol/control/scaleline.js b/src/ol/control/scaleline.js
index 2b28824552..674eb7aadd 100644
--- a/src/ol/control/scaleline.js
+++ b/src/ol/control/scaleline.js
@@ -245,7 +245,7 @@ ol.control.ScaleLine.prototype.updateElement_ = function() {
       pointResolution /= 1609.3472;
     }
   } else {
-    ol.assert(false, 33); // Invalid units
+    ol.asserts.assert(false, 33); // Invalid units
   }
 
   var i = 3 * Math.floor(
diff --git a/src/ol/extent.js b/src/ol/extent.js
index f9da4b4605..f7430cef6d 100644
--- a/src/ol/extent.js
+++ b/src/ol/extent.js
@@ -526,7 +526,7 @@ ol.extent.getCorner = function(extent, corner) {
   } else if (corner === ol.extent.Corner.TOP_RIGHT) {
     coordinate = ol.extent.getTopRight(extent);
   } else {
-    ol.assert(false, 13); // Invalid corner
+    ol.asserts.assert(false, 13); // Invalid corner
   }
   return /** @type {!ol.Coordinate} */ (coordinate);
 };
diff --git a/src/ol/feature.js b/src/ol/feature.js
index a9f351c2bb..0bb9b6b2c5 100644
--- a/src/ol/feature.js
+++ b/src/ol/feature.js
@@ -301,7 +301,7 @@ ol.Feature.createStyleFunction = function(obj) {
     if (Array.isArray(obj)) {
       styles = obj;
     } else {
-      ol.assert(obj instanceof ol.style.Style,
+      ol.asserts.assert(obj instanceof ol.style.Style,
           41); // Expected an `ol.style.Style` or an array of `ol.style.Style`
       styles = [obj];
     }
diff --git a/src/ol/format/esrijson.js b/src/ol/format/esrijson.js
index b183f80b12..97691101c8 100644
--- a/src/ol/format/esrijson.js
+++ b/src/ol/format/esrijson.js
@@ -282,7 +282,7 @@ ol.format.EsriJSON.writePointGeometry_ = function(geometry, opt_options) {
       y: coordinates[1]
     });
   } else {
-    ol.assert(false, 34); // Invalid geometry layout
+    ol.asserts.assert(false, 34); // Invalid geometry layout
   }
   return /** @type {EsriJSONGeometry} */ (esriJSON);
 };
diff --git a/src/ol/format/geojson.js b/src/ol/format/geojson.js
index c0342f1495..b5f82272fc 100644
--- a/src/ol/format/geojson.js
+++ b/src/ol/format/geojson.js
@@ -422,7 +422,7 @@ ol.format.GeoJSON.prototype.readFeaturesFromObject = function(
           opt_options));
     }
   } else {
-    ol.assert(false, 35); // Unknown GeoJSON object type
+    ol.asserts.assert(false, 35); // Unknown GeoJSON object type
   }
   return /** Array.<ol.Feature> */ (features);
 };
@@ -478,7 +478,7 @@ ol.format.GeoJSON.prototype.readProjectionFromObject = function(object) {
       // is fixed and widely deployed.
       projection = ol.proj.get('EPSG:' + crs.properties.code);
     } else {
-      ol.assert(false, 36); // Unknown SRS type
+      ol.asserts.assert(false, 36); // Unknown SRS type
     }
   } else {
     projection = this.defaultDataProjection;
diff --git a/src/ol/format/kml.js b/src/ol/format/kml.js
index 1f119b8665..83c0c3b3b1 100644
--- a/src/ol/format/kml.js
+++ b/src/ol/format/kml.js
@@ -981,7 +981,7 @@ ol.format.KML.readMultiGeometry_ = function(node, objectStack) {
     } else if (type == ol.geom.GeometryType.GEOMETRY_COLLECTION) {
       multiGeometry = new ol.geom.GeometryCollection(geometries);
     } else {
-      ol.assert(false, 37); // Unknown geometry type found
+      ol.asserts.assert(false, 37); // Unknown geometry type found
     }
   } else {
     multiGeometry = new ol.geom.GeometryCollection(geometries);
@@ -1217,7 +1217,7 @@ ol.format.KML.PlacemarkStyleMapParser_ = function(node, objectStack) {
   } else if (typeof styleMapValue === 'string') {
     placemarkObject['styleUrl'] = styleMapValue;
   } else {
-    ol.assert(false, 38); // `styleMapValue` has an unknown type
+    ol.asserts.assert(false, 38); // `styleMapValue` has an unknown type
   }
 };
 
@@ -2067,7 +2067,7 @@ ol.format.KML.writeCoordinatesTextNode_ = function(node, coordinates, objectStac
       layout == ol.geom.GeometryLayout.XYZM) {
     dimension = 3;
   } else {
-    ol.assert(false, 34); // Invalid geometry layout
+    ol.asserts.assert(false, 34); // Invalid geometry layout
   }
 
   var d, i;
@@ -2259,7 +2259,7 @@ ol.format.KML.writeMultiGeometry_ = function(node, geometry, objectStack) {
         (/** @type {ol.geom.MultiPolygon} */ (geometry)).getPolygons();
     factory = ol.format.KML.POLYGON_NODE_FACTORY_;
   } else {
-    ol.assert(false, 39); // Unknown geometry type
+    ol.asserts.assert(false, 39); // Unknown geometry type
   }
   ol.xml.pushSerializeAndPop(context,
       ol.format.KML.MULTI_GEOMETRY_SERIALIZERS_, factory,
diff --git a/src/ol/format/polyline.js b/src/ol/format/polyline.js
index b00d2b2216..a7b3a8ad40 100644
--- a/src/ol/format/polyline.js
+++ b/src/ol/format/polyline.js
@@ -355,7 +355,7 @@ ol.format.Polyline.prototype.writeFeatureText = function(feature, opt_options) {
   if (geometry) {
     return this.writeGeometryText(geometry, opt_options);
   } else {
-    ol.assert(false, 40); // Expected `feature` to have a geometry
+    ol.asserts.assert(false, 40); // Expected `feature` to have a geometry
     return '';
   }
 };
diff --git a/src/ol/format/wfs.js b/src/ol/format/wfs.js
index b76bbbf747..185e5c97e2 100644
--- a/src/ol/format/wfs.js
+++ b/src/ol/format/wfs.js
@@ -386,7 +386,7 @@ ol.format.WFS.writeOgcFidFilter_ = function(node, fid, objectStack) {
  */
 ol.format.WFS.writeDelete_ = function(node, feature, objectStack) {
   var context = objectStack[objectStack.length - 1];
-  ol.assert(feature.getId() !== undefined, 26); // Features must have an id set
+  ol.asserts.assert(feature.getId() !== undefined, 26); // Features must have an id set
   var featureType = context['featureType'];
   var featurePrefix = context['featurePrefix'];
   featurePrefix = featurePrefix ? featurePrefix :
@@ -410,7 +410,7 @@ ol.format.WFS.writeDelete_ = function(node, feature, objectStack) {
  */
 ol.format.WFS.writeUpdate_ = function(node, feature, objectStack) {
   var context = objectStack[objectStack.length - 1];
-  ol.assert(feature.getId() !== undefined, 27); // Features must have an id set
+  ol.asserts.assert(feature.getId() !== undefined, 27); // Features must have an id set
   var featureType = context['featureType'];
   var featurePrefix = context['featurePrefix'];
   featurePrefix = featurePrefix ? featurePrefix :
@@ -802,7 +802,7 @@ ol.format.WFS.prototype.writeGetFeature = function(options) {
     }
     filter = options.filter;
     if (options.bbox) {
-      ol.assert(options.geometryName,
+      ol.asserts.assert(options.geometryName,
           12); // `options.geometryName` must also be provided when `options.bbox` is set
       var bbox = ol.format.ogc.filter.bbox(
           /** @type {string} */ (options.geometryName), options.bbox, options.srsName);
@@ -826,7 +826,7 @@ ol.format.WFS.prototype.writeGetFeature = function(options) {
     'filter': filter,
     'propertyNames': options.propertyNames ? options.propertyNames : []
   };
-  ol.assert(Array.isArray(options.featureTypes),
+  ol.asserts.assert(Array.isArray(options.featureTypes),
       11); // `options.featureTypes` should be an Array
   ol.format.WFS.writeGetFeature_(node, /** @type {!Array.<string>} */ (options.featureTypes), [context]);
   return node;
diff --git a/src/ol/index.js b/src/ol/index.js
index e195cff740..9004ffdbf0 100644
--- a/src/ol/index.js
+++ b/src/ol/index.js
@@ -303,48 +303,3 @@ if (typeof window !== 'undefined') {
 } else if (typeof self !== 'undefined') {
   ol.global = self;
 }
-
-
-/**
- * Error object thrown when an assertion failed. This is an ECMA-262 Error,
- * extended with a `code` property.
- * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error}
- * @constructor
- * @extends {Error}
- * @implements {oli.AssertionError}
- * @param {number} code Error code.
- */
-ol.AssertionError = function(code) {
-
-  /**
-   * @type {string}
-   */
-  this.message = 'Assertion failed. See ' +
-      (ol.VERSION ? 'http://openlayers.org/en/' + ol.VERSION.split('-')[0] : '') +
-      '/doc/errors/#' + code + ' for details.';
-
-  /**
-   * Error code. The meaning of the code can be found on
-   * {@link http://openlayers.org/en/latest/errors.html} (replace `latest` with
-   * the version found in the OpenLayers script's header comment if a version
-   * other than the latest is used).
-   * @type {number}
-   * @api
-   */
-  this.code = code;
-
-  this.name = 'AssertionError';
-
-};
-ol.inherits(ol.AssertionError, Error);
-
-
-/**
- * @param {*} assertion Assertion we expected to be truthy.
- * @param {number} errorCode Error code.
- */
-ol.assert = function(assertion, errorCode) {
-  if (!assertion) {
-    throw new ol.AssertionError(errorCode);
-  }
-};
diff --git a/src/ol/interaction/select.js b/src/ol/interaction/select.js
index ef634e00b0..eadcfe787c 100644
--- a/src/ol/interaction/select.js
+++ b/src/ol/interaction/select.js
@@ -225,7 +225,7 @@ ol.interaction.Select.prototype.getFeatures = function() {
  * @api
  */
 ol.interaction.Select.prototype.getLayer = function(feature) {
-  ol.assert(feature instanceof ol.Feature,
+  ol.asserts.assert(feature instanceof ol.Feature,
       42); // Expected an `ol.Feature`, but got an `ol.RenderFeature`
   var key = ol.getUid(feature);
   return /** @type {ol.layer.Vector} */ (this.featureLayerAssociation_[key]);
diff --git a/src/ol/layer/group.js b/src/ol/layer/group.js
index f982001055..4406463e71 100644
--- a/src/ol/layer/group.js
+++ b/src/ol/layer/group.js
@@ -61,7 +61,7 @@ ol.layer.Group = function(opt_options) {
     if (Array.isArray(layers)) {
       layers = new ol.Collection(layers.slice());
     } else {
-      ol.assert(layers instanceof ol.Collection,
+      ol.asserts.assert(layers instanceof ol.Collection,
           43); // Expected `layers` to be an array or an `ol.Collection`
       layers = layers;
     }
diff --git a/src/ol/layer/vectortile.js b/src/ol/layer/vectortile.js
index fd84333365..6a3410cb0e 100644
--- a/src/ol/layer/vectortile.js
+++ b/src/ol/layer/vectortile.js
@@ -58,7 +58,7 @@ ol.layer.VectorTile = function(opt_options) {
   this.setUseInterimTilesOnError(options.useInterimTilesOnError ?
       options.useInterimTilesOnError : true);
 
-  ol.assert(options.renderMode == undefined ||
+  ol.asserts.assert(options.renderMode == undefined ||
       options.renderMode == ol.layer.VectorTileRenderType.IMAGE ||
       options.renderMode == ol.layer.VectorTileRenderType.HYBRID ||
       options.renderMode == ol.layer.VectorTileRenderType.VECTOR,
diff --git a/src/ol/map.js b/src/ol/map.js
index 37d19f6fbc..441c632ff7 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -1443,8 +1443,8 @@ ol.Map.createOptionsInternal = function(options) {
     } else if (logo instanceof HTMLElement) {
       logos[ol.getUid(logo).toString()] = logo;
     } else if (logo) {
-      ol.assert(typeof logo.href == 'string', 44); // `logo.href` should be a string.
-      ol.assert(typeof logo.src == 'string', 45); // `logo.src` should be a string.
+      ol.asserts.assert(typeof logo.href == 'string', 44); // `logo.href` should be a string.
+      ol.asserts.assert(typeof logo.src == 'string', 45); // `logo.src` should be a string.
       logos[logo.src] = logo.href;
     }
   }
@@ -1473,7 +1473,7 @@ ol.Map.createOptionsInternal = function(options) {
     } else if (typeof options.renderer === 'string') {
       rendererTypes = [options.renderer];
     } else {
-      ol.assert(false, 46); // Incorrect format for `renderer` option
+      ol.asserts.assert(false, 46); // Incorrect format for `renderer` option
     }
   } else {
     rendererTypes = ol.DEFAULT_RENDERER_TYPES;
@@ -1506,7 +1506,7 @@ ol.Map.createOptionsInternal = function(options) {
     if (Array.isArray(options.controls)) {
       controls = new ol.Collection(options.controls.slice());
     } else {
-      ol.assert(options.controls instanceof ol.Collection,
+      ol.asserts.assert(options.controls instanceof ol.Collection,
           47); // Expected `controls` to be an array or an `ol.Collection`
       controls = options.controls;
     }
@@ -1519,7 +1519,7 @@ ol.Map.createOptionsInternal = function(options) {
     if (Array.isArray(options.interactions)) {
       interactions = new ol.Collection(options.interactions.slice());
     } else {
-      ol.assert(options.interactions instanceof ol.Collection,
+      ol.asserts.assert(options.interactions instanceof ol.Collection,
           48); // Expected `interactions` to be an array or an `ol.Collection`
       interactions = options.interactions;
     }
@@ -1532,7 +1532,7 @@ ol.Map.createOptionsInternal = function(options) {
     if (Array.isArray(options.overlays)) {
       overlays = new ol.Collection(options.overlays.slice());
     } else {
-      ol.assert(options.overlays instanceof ol.Collection,
+      ol.asserts.assert(options.overlays instanceof ol.Collection,
           49); // Expected `overlays` to be an array or an `ol.Collection`
       overlays = options.overlays;
     }
diff --git a/src/ol/math.js b/src/ol/math.js
index 96892c6818..d5308896b6 100644
--- a/src/ol/math.js
+++ b/src/ol/math.js
@@ -46,7 +46,7 @@ ol.math.cosh = (function() {
  * @return {number} The smallest power of two greater than or equal to x.
  */
 ol.math.roundUpToPowerOfTwo = function(x) {
-  ol.assert(0 < x, 29); // `x` must be greater than `0`
+  ol.asserts.assert(0 < x, 29); // `x` must be greater than `0`
   return Math.pow(2, Math.ceil(Math.log(x) / Math.LN2));
 };
 
diff --git a/src/ol/renderer/layer.js b/src/ol/renderer/layer.js
index 341d4f94db..15ff460287 100644
--- a/src/ol/renderer/layer.js
+++ b/src/ol/renderer/layer.js
@@ -221,8 +221,8 @@ ol.renderer.Layer.prototype.updateLogos = function(frameState, source) {
     if (typeof logo === 'string') {
       frameState.logos[logo] = '';
     } else if (logo) {
-      ol.assert(typeof logo.href == 'string', 44); // `logo.href` should be a string.
-      ol.assert(typeof logo.src == 'string', 45); // `logo.src` should be a string.
+      ol.asserts.assert(typeof logo.href == 'string', 44); // `logo.href` should be a string.
+      ol.asserts.assert(typeof logo.src == 'string', 45); // `logo.src` should be a string.
       frameState.logos[logo.src] = logo.href;
     }
   }
diff --git a/src/ol/source/cluster.js b/src/ol/source/cluster.js
index 074ce99acd..b49a5978cf 100644
--- a/src/ol/source/cluster.js
+++ b/src/ol/source/cluster.js
@@ -55,7 +55,7 @@ ol.source.Cluster = function(options) {
    */
   this.geometryFunction_ = options.geometryFunction || function(feature) {
     var geometry = /** @type {ol.geom.Point} */ (feature.getGeometry());
-    ol.assert(geometry instanceof ol.geom.Point,
+    ol.asserts.assert(geometry instanceof ol.geom.Point,
         10); // The default `geometryFunction` can only handle `ol.geom.Point` geometries
     return geometry;
   };
diff --git a/src/ol/source/imagearcgisrest.js b/src/ol/source/imagearcgisrest.js
index cae2c0b250..9a5ea2b299 100644
--- a/src/ol/source/imagearcgisrest.js
+++ b/src/ol/source/imagearcgisrest.js
@@ -211,7 +211,7 @@ ol.source.ImageArcGISRest.prototype.getRequestUrl_ = function(extent, size, pixe
     .replace(/MapServer\/?$/, 'MapServer/export')
     .replace(/ImageServer\/?$/, 'ImageServer/exportImage');
   if (modifiedUrl == url) {
-    ol.assert(false, 50); // `options.featureTypes` should be an Array
+    ol.asserts.assert(false, 50); // `options.featureTypes` should be an Array
   }
   return ol.uri.appendParams(modifiedUrl, params);
 };
diff --git a/src/ol/source/imagewms.js b/src/ol/source/imagewms.js
index 5b0f1a3e8c..f28dce2897 100644
--- a/src/ol/source/imagewms.js
+++ b/src/ol/source/imagewms.js
@@ -267,7 +267,7 @@ ol.source.ImageWMS.prototype.getImageLoadFunction = function() {
  */
 ol.source.ImageWMS.prototype.getRequestUrl_ = function(extent, size, pixelRatio, projection, params) {
 
-  ol.assert(this.url_ !== undefined, 9); // `url` must be configured or set using `#setUrl()`
+  ol.asserts.assert(this.url_ !== undefined, 9); // `url` must be configured or set using `#setUrl()`
 
   params[this.v13_ ? 'CRS' : 'SRS'] = projection.getCode();
 
@@ -293,7 +293,7 @@ ol.source.ImageWMS.prototype.getRequestUrl_ = function(extent, size, pixelRatio,
         params['DPI'] = 90 * pixelRatio;
         break;
       default:
-        ol.assert(false, 8); // Unknown `serverType` configured
+        ol.asserts.assert(false, 8); // Unknown `serverType` configured
         break;
     }
   }
diff --git a/src/ol/source/tilearcgisrest.js b/src/ol/source/tilearcgisrest.js
index ef8f3f0bdb..f8d68389f4 100644
--- a/src/ol/source/tilearcgisrest.js
+++ b/src/ol/source/tilearcgisrest.js
@@ -110,7 +110,7 @@ ol.source.TileArcGISRest.prototype.getRequestUrl_ = function(tileCoord, tileSize
       .replace(/MapServer\/?$/, 'MapServer/export')
       .replace(/ImageServer\/?$/, 'ImageServer/exportImage');
   if (modifiedUrl == url) {
-    ol.assert(false, 50); // Cannot determine Rest Service from url
+    ol.asserts.assert(false, 50); // Cannot determine Rest Service from url
   }
   return ol.uri.appendParams(modifiedUrl, params);
 };
diff --git a/src/ol/source/tileutfgrid.js b/src/ol/source/tileutfgrid.js
index c11c500345..7111861fdd 100644
--- a/src/ol/source/tileutfgrid.js
+++ b/src/ol/source/tileutfgrid.js
@@ -69,7 +69,7 @@ ol.source.TileUTFGrid = function(options) {
   } else if (options.tileJSON) {
     this.handleTileJSONResponse(options.tileJSON);
   } else {
-    ol.assert(false, 51); // Either `url` or `tileJSON` options must be provided
+    ol.asserts.assert(false, 51); // Either `url` or `tileJSON` options must be provided
   }
 };
 ol.inherits(ol.source.TileUTFGrid, ol.source.Tile);
diff --git a/src/ol/source/tilewms.js b/src/ol/source/tilewms.js
index ad8070074d..f4d111f4c4 100644
--- a/src/ol/source/tilewms.js
+++ b/src/ol/source/tilewms.js
@@ -237,7 +237,7 @@ ol.source.TileWMS.prototype.getRequestUrl_ = function(tileCoord, tileSize, tileE
         params['DPI'] = 90 * pixelRatio;
         break;
       default:
-        ol.assert(false, 52); // Unknown `serverType` configured
+        ol.asserts.assert(false, 52); // Unknown `serverType` configured
         break;
     }
   }
diff --git a/src/ol/source/vector.js b/src/ol/source/vector.js
index dbefbe8352..7cec3a8edc 100644
--- a/src/ol/source/vector.js
+++ b/src/ol/source/vector.js
@@ -101,7 +101,7 @@ ol.source.Vector = function(opt_options) {
   if (options.loader !== undefined) {
     this.loader_ = options.loader;
   } else if (this.url_ !== undefined) {
-    ol.assert(this.format_, 7); // `format` must be set when `url` is set
+    ol.asserts.assert(this.format_, 7); // `format` must be set when `url` is set
     // create a XHR feature loader for "url" and "format"
     this.loader_ = ol.featureloader.xhr(this.url_, /** @type {ol.format.Feature} */ (this.format_));
   }
@@ -257,7 +257,7 @@ ol.source.Vector.prototype.addToIndex_ = function(featureKey, feature) {
       valid = false;
     }
   } else {
-    ol.assert(!(featureKey in this.undefIdIndex_),
+    ol.asserts.assert(!(featureKey in this.undefIdIndex_),
         30); // The passed `feature` was already added to the source
     this.undefIdIndex_[featureKey] = feature;
   }
diff --git a/src/ol/source/zoomify.js b/src/ol/source/zoomify.js
index cba5e88750..e2311082ce 100644
--- a/src/ol/source/zoomify.js
+++ b/src/ol/source/zoomify.js
@@ -64,7 +64,7 @@ ol.source.Zoomify = function(opt_options) {
       }
       break;
     default:
-      ol.assert(false, 53); // Unknown `tierSizeCalculation` configured
+      ol.asserts.assert(false, 53); // Unknown `tierSizeCalculation` configured
       break;
   }
 
diff --git a/src/ol/structs/lrucache.js b/src/ol/structs/lrucache.js
index b8735f573b..1614780f2b 100644
--- a/src/ol/structs/lrucache.js
+++ b/src/ol/structs/lrucache.js
@@ -130,7 +130,7 @@ ol.structs.LRUCache.prototype.forEach = function(f, opt_this) {
  */
 ol.structs.LRUCache.prototype.get = function(key) {
   var entry = this.entries_[key];
-  ol.assert(entry !== undefined,
+  ol.asserts.assert(entry !== undefined,
       15); // Tried to get a value for a key that does not exist in the cache
   if (entry === this.newest_) {
     return entry.value_;
@@ -244,7 +244,7 @@ ol.structs.LRUCache.prototype.replace = function(key, value) {
 ol.structs.LRUCache.prototype.set = function(key, value) {
   goog.DEBUG && console.assert(!(key in {}),
       'key is not a standard property of objects (e.g. "__proto__")');
-  ol.assert(!(key in this.entries_),
+  ol.asserts.assert(!(key in this.entries_),
       16); // Tried to set a value for a key that is used already
   var entry = /** @type {ol.LRUCacheEntry} */ ({
     key_: key,
diff --git a/src/ol/structs/priorityqueue.js b/src/ol/structs/priorityqueue.js
index dc2dfb9270..2a597ef210 100644
--- a/src/ol/structs/priorityqueue.js
+++ b/src/ol/structs/priorityqueue.js
@@ -125,7 +125,7 @@ ol.structs.PriorityQueue.prototype.dequeue = function() {
  * @return {boolean} The element was added to the queue.
  */
 ol.structs.PriorityQueue.prototype.enqueue = function(element) {
-  ol.assert(!(this.keyFunction_(element) in this.queuedElements_),
+  ol.asserts.assert(!(this.keyFunction_(element) in this.queuedElements_),
       31); // Tried to enqueue an `element` that was already added to the queue
   var priority = this.priorityFunction_(element);
   if (priority != ol.structs.PriorityQueue.DROP) {
diff --git a/src/ol/style/icon.js b/src/ol/style/icon.js
index 5ea231e890..9483d44689 100644
--- a/src/ol/style/icon.js
+++ b/src/ol/style/icon.js
@@ -101,15 +101,15 @@ ol.style.Icon = function(opt_options) {
    */
   var src = options.src;
 
-  ol.assert(!(src !== undefined && image),
+  ol.asserts.assert(!(src !== undefined && image),
       4); // `image` and `src` cannot be provided at the same time
-  ol.assert(!image || (image && imgSize),
+  ol.asserts.assert(!image || (image && imgSize),
       5); // `imgSize` must be set when `image` is provided
 
   if ((src === undefined || src.length === 0) && image) {
     src = image.src || ol.getUid(image).toString();
   }
-  ol.assert(src !== undefined && src.length > 0,
+  ol.asserts.assert(src !== undefined && src.length > 0,
       6); // A defined and non-empty `src` or `image` must be provided
 
   /**
diff --git a/src/ol/style/style.js b/src/ol/style/style.js
index e19e814963..e0210b3755 100644
--- a/src/ol/style/style.js
+++ b/src/ol/style/style.js
@@ -201,7 +201,7 @@ ol.style.createStyleFunction = function(obj) {
     if (Array.isArray(obj)) {
       styles = obj;
     } else {
-      ol.assert(obj instanceof ol.style.Style,
+      ol.asserts.assert(obj instanceof ol.style.Style,
           41); // Expected an `ol.style.Style` or an array of `ol.style.Style`
       styles = [obj];
     }
diff --git a/src/ol/tilegrid/tilegrid.js b/src/ol/tilegrid/tilegrid.js
index 9971bdbdd3..f66b0ece9d 100644
--- a/src/ol/tilegrid/tilegrid.js
+++ b/src/ol/tilegrid/tilegrid.js
@@ -32,7 +32,7 @@ ol.tilegrid.TileGrid = function(options) {
    * @type {!Array.<number>}
    */
   this.resolutions_ = options.resolutions;
-  ol.assert(ol.array.isSorted(this.resolutions_, function(a, b) {
+  ol.asserts.assert(ol.array.isSorted(this.resolutions_, function(a, b) {
     return b - a;
   }, true), 17); // `resolutions` must be sorted in descending order
 
@@ -55,7 +55,7 @@ ol.tilegrid.TileGrid = function(options) {
   this.origins_ = null;
   if (options.origins !== undefined) {
     this.origins_ = options.origins;
-    ol.assert(this.origins_.length == this.resolutions_.length,
+    ol.asserts.assert(this.origins_.length == this.resolutions_.length,
         20); // Number of `origins` and `resolutions` must be equal
   }
 
@@ -66,7 +66,7 @@ ol.tilegrid.TileGrid = function(options) {
     this.origin_ = ol.extent.getTopLeft(extent);
   }
 
-  ol.assert(
+  ol.asserts.assert(
       (!this.origin_ && this.origins_) || (this.origin_ && !this.origins_),
       18); // Either `origin` or `origins` must be configured, never both
 
@@ -77,7 +77,7 @@ ol.tilegrid.TileGrid = function(options) {
   this.tileSizes_ = null;
   if (options.tileSizes !== undefined) {
     this.tileSizes_ = options.tileSizes;
-    ol.assert(this.tileSizes_.length == this.resolutions_.length,
+    ol.asserts.assert(this.tileSizes_.length == this.resolutions_.length,
         19); // Number of `tileSizes` and `resolutions` must be equal
   }
 
@@ -88,7 +88,7 @@ ol.tilegrid.TileGrid = function(options) {
   this.tileSize_ = options.tileSize !== undefined ?
       options.tileSize :
       !this.tileSizes_ ? ol.DEFAULT_TILE_SIZE : null;
-  ol.assert(
+  ol.asserts.assert(
       (!this.tileSize_ && this.tileSizes_) ||
       (this.tileSize_ && !this.tileSizes_),
       22); // Either `tileSize` or `tileSizes` must be configured, never both
@@ -122,7 +122,7 @@ ol.tilegrid.TileGrid = function(options) {
           Math.min(0, size[0]), Math.max(size[0] - 1, -1),
           Math.min(0, size[1]), Math.max(size[1] - 1, -1));
       if (this.minZoom <= z && z <= this.maxZoom && extent !== undefined) {
-        ol.assert(tileRange.containsTileRange(
+        ol.asserts.assert(tileRange.containsTileRange(
             this.getTileRangeForExtentAndZ(extent, z)),
             21); // Tile range for `extent` must not exceed tilegrid width and height
       }
diff --git a/src/ol/tilerange.js b/src/ol/tilerange.js
index 727bc08771..9575b6495a 100644
--- a/src/ol/tilerange.js
+++ b/src/ol/tilerange.js
@@ -54,7 +54,7 @@ ol.TileRange.boundingTileRange = function(var_args) {
     tileCoordZ = tileCoord[0];
     tileCoordX = tileCoord[1];
     tileCoordY = tileCoord[2];
-    ol.assert(tileCoordZ == tileCoord0Z,
+    ol.asserts.assert(tileCoordZ == tileCoord0Z,
         23); // The passed `ol.TileCoord`s must all have the same `z` value
     tileRange.minX = Math.min(tileRange.minX, tileCoordX);
     tileRange.maxX = Math.max(tileRange.maxX, tileCoordX);
diff --git a/src/ol/tileurlfunction.js b/src/ol/tileurlfunction.js
index f03c4fef19..cbaa718fab 100644
--- a/src/ol/tileurlfunction.js
+++ b/src/ol/tileurlfunction.js
@@ -34,7 +34,7 @@ ol.TileUrlFunction.createFromTemplate = function(template, tileGrid) {
               .replace(dashYRegEx, function() {
                 var z = tileCoord[0];
                 var range = tileGrid.getFullTileRange(z);
-                ol.assert(range, 55); // The {-y} placeholder requires a tile grid with extent
+                ol.asserts.assert(range, 55); // The {-y} placeholder requires a tile grid with extent
                 var y = range.getHeight() + tileCoord[2];
                 return y.toString();
               });
diff --git a/src/ol/transform.js b/src/ol/transform.js
index ec8dd97147..5bf0e9030d 100644
--- a/src/ol/transform.js
+++ b/src/ol/transform.js
@@ -199,7 +199,7 @@ ol.transform.compose = function(transform, dx1, dy1, sx, sy, angle, dx2, dy2) {
  */
 ol.transform.invert = function(transform) {
   var det = ol.transform.determinant(transform);
-  ol.assert(det !== 0, 32); // Transformation matrix cannot be inverted
+  ol.asserts.assert(det !== 0, 32); // Transformation matrix cannot be inverted
 
   var a = transform[0];
   var b = transform[1];
diff --git a/src/ol/view.js b/src/ol/view.js
index afeb8cf404..04f3323b9f 100644
--- a/src/ol/view.js
+++ b/src/ol/view.js
@@ -289,11 +289,11 @@ ol.View.prototype.getHints = function(opt_hints) {
  */
 ol.View.prototype.calculateExtent = function(size) {
   var center = /** @type {!ol.Coordinate} */ (this.getCenter());
-  ol.assert(center, 1); // The view center is not defined
+  ol.asserts.assert(center, 1); // The view center is not defined
   var resolution = /** @type {!number} */ (this.getResolution());
-  ol.assert(resolution !== undefined, 2); // The view resolution is not defined
+  ol.asserts.assert(resolution !== undefined, 2); // The view resolution is not defined
   var rotation = /** @type {!number} */ (this.getRotation());
-  ol.assert(rotation !== undefined, 3); // The view rotation is not defined
+  ol.asserts.assert(rotation !== undefined, 3); // The view rotation is not defined
 
   return ol.extent.getForViewAndSize(center, resolution, rotation, size);
 };
@@ -492,9 +492,9 @@ ol.View.prototype.getZoom = function() {
  */
 ol.View.prototype.fit = function(geometry, size, opt_options) {
   if (!(geometry instanceof ol.geom.SimpleGeometry)) {
-    ol.assert(Array.isArray(geometry),
+    ol.asserts.assert(Array.isArray(geometry),
         24); // Invalid extent or geometry provided as `geometry`
-    ol.assert(!ol.extent.isEmpty(geometry),
+    ol.asserts.assert(!ol.extent.isEmpty(geometry),
         25); // Cannot fit empty extent provided as `geometry`
     geometry = ol.geom.Polygon.fromExtent(geometry);
   }
diff --git a/test/spec/ol/assertionerror.test.js b/test/spec/ol/assertionerror.test.js
new file mode 100644
index 0000000000..b81f69264e
--- /dev/null
+++ b/test/spec/ol/assertionerror.test.js
@@ -0,0 +1,26 @@
+goog.provide('ol.AssertionError.test');
+
+goog.require('ol');
+goog.require('ol.AssertionError');
+
+describe('ol.AssertionError', function() {
+  it('generates a message', function() {
+    var error = new ol.AssertionError(42);
+    expect(error.message).to.be('Assertion failed. See /doc/errors/#42 for details.');
+  });
+  it('generates a message with a versioned url', function() {
+    var origVersion = ol.VERSION;
+    ol.VERSION = 'foo';
+    var error = new ol.AssertionError(42);
+    expect(error.message).to.be('Assertion failed. See http://openlayers.org/en/foo/doc/errors/#42 for details.');
+    ol.VERSION = origVersion;
+  });
+  it('has an error code', function() {
+    var error = new ol.AssertionError(42);
+    expect(error.code).to.be(42);
+  });
+  it('has a name', function() {
+    var error = new ol.AssertionError(42);
+    expect(error.name).to.be('AssertionError');
+  });
+});
diff --git a/test/spec/ol/asserts.test.js b/test/spec/ol/asserts.test.js
new file mode 100644
index 0000000000..4e250b3a85
--- /dev/null
+++ b/test/spec/ol/asserts.test.js
@@ -0,0 +1,16 @@
+goog.provide('ol.asserts.asserts.test');
+
+goog.require('ol.asserts');
+
+
+describe('ol.asserts', function() {
+
+  describe('ol.asserts.assert', function() {
+    it('throws an exception', function() {
+      expect(function() {
+        ol.asserts.assert(false, 42);
+      }).to.throwException();
+    });
+  });
+
+});
diff --git a/test/spec/ol/ol.test.js b/test/spec/ol/ol.test.js
deleted file mode 100644
index 8ad3ba3dc6..0000000000
--- a/test/spec/ol/ol.test.js
+++ /dev/null
@@ -1,38 +0,0 @@
-goog.provide('ol.test');
-
-goog.require('ol');
-
-
-describe('ol', function() {
-
-  describe('ol.assert', function() {
-    it('throws an exception', function() {
-      expect(function() {
-        ol.assert(false, 42);
-      }).to.throwException();
-    });
-  });
-
-  describe('ol.AssertionError', function() {
-    it('generates a message', function() {
-      var error = new ol.AssertionError(42);
-      expect(error.message).to.be('Assertion failed. See /doc/errors/#42 for details.');
-    });
-    it('generates a message with a versioned url', function() {
-      var origVersion = ol.VERSION;
-      ol.VERSION = 'foo';
-      var error = new ol.AssertionError(42);
-      expect(error.message).to.be('Assertion failed. See http://openlayers.org/en/foo/doc/errors/#42 for details.');
-      ol.VERSION = origVersion;
-    });
-    it('has an error code', function() {
-      var error = new ol.AssertionError(42);
-      expect(error.code).to.be(42);
-    });
-    it('has a name', function() {
-      var error = new ol.AssertionError(42);
-      expect(error.name).to.be('AssertionError');
-    });
-  });
-
-});
diff --git a/test/spec/ol/view.test.js b/test/spec/ol/view.test.js
index ba006097fa..2d32a12adb 100644
--- a/test/spec/ol/view.test.js
+++ b/test/spec/ol/view.test.js
@@ -1,5 +1,6 @@
 goog.provide('ol.test.View');
 
+goog.require('ol');
 goog.require('ol.View');
 goog.require('ol.extent');
 goog.require('ol.geom.LineString');