add test for constraintCheck

test/lps.js/utility/constraintCheck.test.js

@@ -0,0 +1,39 @@
+/*
+  This file is part of the lps.js project, released open source under
+  the BSD 3-Clause license. For more info, please see https://github.com/mauris/lps.js
+ */
+
+const constraintCheck = lpsRequire('utility/constraintCheck');
+const Functor = lpsRequire('engine/Functor');
+const Clause = lpsRequire('engine/Clause');
+const Variable = lpsRequire('engine/Variable');
+const Value = lpsRequire('engine/Value');
+const Program = lpsRequire('engine/Program');
+const LiteralTreeMap = lpsRequire('engine/LiteralTreeMap');
+const Engine = lpsRequire('engine/Engine');
+
+const chai = require('chai');
+const expect = chai.expect;
+
+describe('constraintCheck', () => {
+  it('should return false on constraint failure', () => {
+    let constraint = new Clause(
+      [],
+      [
+        new Functor('lend', [new Variable('Person'), new Variable('Person'), new Variable('Amount')])
+      ]
+    );
+
+    let events = new LiteralTreeMap();
+    events.add(new Functor('lend', [new Functor('alice', []), new Functor('alice', []), new Value(15)]));
+
+    let program = new Program();
+    program.setConstraints([constraint]);
+    program.setExecutedActions(events);
+
+    let engine = new Engine(program);
+
+    let result = constraintCheck(engine, program);
+    expect(result).to.be.false;
+  });
+});