Add a concat function for concatenating strings

test/spec/ol/expr/expression.test.js

@@ -628,6 +628,52 @@ describe('ol.expr.lib', function() {
   var parse = ol.expr.parse;
   var evaluate = ol.expr.evaluateFeature;
 
+  describe('concat()', function() {
+    var feature = new ol.Feature({
+      str: 'bar',
+      num: 42,
+      bool: false,
+      nul: null
+    });
+
+    it('concatenates strings', function() {
+      expect(evaluate(parse('concat(str, "after")'), feature))
+          .to.be('barafter');
+      expect(evaluate(parse('concat("before", str)'), feature))
+          .to.be('beforebar');
+      expect(evaluate(parse('concat("a", str, "b")'), feature))
+          .to.be('abarb');
+    });
+
+    it('concatenates numbers as strings', function() {
+      expect(evaluate(parse('concat(num, 0)'), feature))
+          .to.be('420');
+      expect(evaluate(parse('concat(0, num)'), feature))
+          .to.be('042');
+      expect(evaluate(parse('concat(42, 42)'), feature))
+          .to.be('4242');
+      expect(evaluate(parse('concat(str, num)'), feature))
+          .to.be('bar42');
+    });
+
+    it('concatenates booleans as strings', function() {
+      expect(evaluate(parse('concat(bool, "foo")'), feature))
+          .to.be('falsefoo');
+      expect(evaluate(parse('concat(true, str)'), feature))
+          .to.be('truebar');
+      expect(evaluate(parse('concat(true, false)'), feature))
+          .to.be('truefalse');
+    });
+
+    it('concatenates nulls as strings', function() {
+      expect(evaluate(parse('concat(nul, "foo")'), feature))
+          .to.be('nullfoo');
+      expect(evaluate(parse('concat(str, null)'), feature))
+          .to.be('barnull');
+    });
+
+  });
+
   describe('extent()', function() {
 
     var nw = new ol.Feature({