Add test for duplicated attribution

test/spec/ol/control/attribution.test.js

@@ -0,0 +1,76 @@
+goog.provide('ol.test.control.Attribution');
+
+goog.require('ol.Map');
+goog.require('ol.View');
+goog.require('ol.control.Attribution');
+goog.require('ol.layer.Tile');
+goog.require('ol.source.Tile');
+
+describe('ol.control.Attribution', function() {
+
+  var map, target;
+  beforeEach(function() {
+    target = document.createElement('div');
+    target.style.width = target.style.height = '100px';
+    document.body.appendChild(target);
+    map = new ol.Map({
+      target: target,
+      controls: [new ol.control.Attribution({
+        collapsed: false,
+        collapsible: false
+      })],
+      layers: [
+        new ol.layer.Tile({
+          source: new ol.source.Tile({
+            projection: 'EPSG:3857',
+            tileGrid: ol.tilegrid.createXYZ(),
+            attributions: 'foo'
+          })
+        }),
+        new ol.layer.Tile({
+          source: new ol.source.Tile({
+            projection: 'EPSG:3857',
+            tileGrid: ol.tilegrid.createXYZ(),
+            attributions: 'bar'
+          })
+        }),
+        new ol.layer.Tile({
+          source: new ol.source.Tile({
+            projection: 'EPSG:3857',
+            tileGrid: ol.tilegrid.createXYZ(),
+            attributions: 'foo'
+          })
+        })
+      ],
+      view: new ol.View({
+        center: [0, 0],
+        zoom: 0
+      })
+    });
+    map.getLayers().forEach(function(layer) {
+      var source = layer.getSource();
+      source.getTile = function() {
+        var tile = new ol.Tile([0, 0, -1], 2 /* LOADED */);
+        tile.getImage = function() {
+          var image = new Image();
+          image.width = 256;
+          image.height = 256;
+          return image;
+        };
+        return tile;
+      };
+    });
+  });
+
+  afterEach(function() {
+    map.setTarget(null);
+    document.body.removeChild(target);
+  });
+
+  it('does not add duplicate attributions', function() {
+    map.renderSync();
+    var attribution = document.querySelectorAll('.ol-attribution li');
+    expect(attribution.length).to.be(3); // first <li> is the logo
+  });
+
+});