add tests for expressions

test/expression.test.js

@@ -0,0 +1,33 @@
+var mapnik = require('mapnik');
+var assert = require('assert');
+
+exports['test expression'] = function(beforeExit) {
+    // no 'new' keyword
+    assert.throws(function() { mapnik.Expression(); });
+
+    // invalid args
+    assert.throws(function() { new mapnik.Expression(); });
+    assert.throws(function() { new mapnik.Expression(1); });
+
+    // valid expression strings
+    var expr = new mapnik.Expression('[ATTR]');
+    var expr = new mapnik.Expression('[ATTR]+2');
+    var expr = new mapnik.Expression('[ATTR]/2');
+
+    var expr = new mapnik.Expression('[ATTR1]/[ATTR2]');
+    assert.equal(expr.toString(),'[ATTR1]/[ATTR2]');
+
+    var expr = new mapnik.Expression('\'literal\'');
+    assert.equal(expr.toString(),"'literal'");
+};
+
+
+exports['test expression evaluation'] = function(beforeExit) {
+
+    var expr = new mapnik.Expression("[attr]='value'");
+    var feature = new mapnik.Feature(0);
+    feature.addAttributes({'attr':'value'});
+    assert.equal(expr.evaluate(feature),true);
+    assert.equal(expr.evaluate(feature).toString(),'true');
+
+};