Add a Port pool manager to handle specific port atribution

lib/PortManager.test.js

@@ -0,0 +1,51 @@
+import assert from 'assert';
+
+import PortManager from './PortManager';
+
+describe('PortManager', () => {
+    it('should construct with no range', () => {
+      const portManager = new PortManager({});
+      assert.equal(portManager.range, null);
+      assert.equal(portManager.first, null);
+      assert.equal(portManager.last, null);
+    });
+
+    it('should construct with range', () => {
+      const portManager = new PortManager({range: '10:20'});
+      assert.equal(portManager.range, '10:20');
+      assert.equal(portManager.first, 10);
+      assert.equal(portManager.last, 20);
+    });
+
+    it('should not construct with bad range expression', () => {
+      assert.throws(()=>{
+        new PortManager({range: 'a1020'});
+      }, /Bad range expression: a1020/)
+    });
+
+    it('should not construct with bad range max>min', () => {
+      assert.throws(()=>{
+        new PortManager({range: '20:10'});
+      }, /Bad range expression min > max: 20:10/)
+    });
+
+    it('should work has expected', async () => {
+      const portManager = new PortManager({range: '10:12'});
+      assert.equal(10,portManager.getNextAvailable('a'));
+      assert.equal(11,portManager.getNextAvailable('b'));
+      assert.equal(12,portManager.getNextAvailable('c'));
+
+      assert.throws(()=>{
+        portManager.getNextAvailable();
+      }, /No more ports available in range 10:12/)
+
+      portManager.release(11);
+      assert.equal(11,portManager.getNextAvailable('bb'));
+
+      portManager.release(10);
+      portManager.release(12);
+
+      assert.equal(10,portManager.getNextAvailable('cc'));
+      assert.equal(12,portManager.getNextAvailable('dd'));
+    });
+});