Checks for negative numbers in an Area

main.js

@@ -5,15 +5,17 @@ class House {
     this.name = nameString;
     this.rooms = [];
   }
+
   addRoom(room) {
     this.rooms.push(room);
+    return this;
   }
+
   area() {
     return this.rooms.reduce((acc, e) => {
       return acc + e.area();
     }, 0);
   }
-
 }
 
 
@@ -22,6 +24,8 @@ class Room {
     // super(options);
     let { width, length } = options;
     if (!width || !length) { throw new Error("Missing params"); }
+    if (width < 0 || length < 0) { throw new Error("Dimensions outside range"); }
+
     this.length = length;
     this.width = width;
   }
@@ -56,6 +60,13 @@ describe("House", () => {
       expect( () => { new Room }).to.throw("Missing params");
     });
 
+    it("throws an error if a dimension is negative", () => {
+
+      expect(() => {
+        let room1 = new Room({width: -7, length: 8});
+      }).to.throw("Dimensions outside range");
+    });
+
     it("accepts width and length arguments", () => {
       let room1 = new Room({ width: 7, length: 8 });
       let room2 = new Room({ width: 5, length: 15 });
@@ -92,7 +103,8 @@ describe("House", () => {
       expect(house1.area()).to.equal(131)
       expect(house2.area()).to.equal(88);
     });
+
   });
 
 
-});
+});

package.json

@@ -9,6 +9,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
-    "chai": "^3.2.0"
+    "chai": "^3.2.0",
+    "mocha": "^2.3.1"
   }
 }