Add test cases for multiply prompt

Author: mybrainishuge

spec/part1.js

@@ -480,16 +480,40 @@
         expect(multiply.toString()).to.not.contain('Math');
       });
 
-      it('should return the product of two integers', function() {
-        expect(multiply(2, 1)).to.equal(2 * 1);
+      it('should return the product of two positive integers', function() {
+        expect(multiply(1, 2)).to.equal(1 * 2);
+        expect(multiply(2, 1)).to.equal(1 * 2);
+        expect(multiply(5, 17)).to.equal(5 * 17);
         expect(multiply(17, 5)).to.equal(17 * 5);
         expect(multiply(78, 453)).to.equal(78 * 453);
-        expect(multiply(-79, 82)).to.equal(-79 * 82);
-        expect(multiply(-275, -502)).to.equal(-275 * -502);
+        expect(multiply(453, 78)).to.equal(78 * 453);
         expect(multiply(0, 32)).to.equal(0 * 32);
+        expect(multiply(32, 0)).to.equal(0 * 32);
         expect(multiply(0, 0)).to.equal(0 * 0);
       });
 
+      it('should return the product of two negative integers', function() {
+        expect(multiply(-79, -82)).to.equal(-79 * -82);
+        expect(multiply(-275, -502)).to.equal(-275 * -502);
+        expect(multiply(-2, -2)).to.equal(-2 * -2);
+        expect(multiply(-8, -3)).to.equal(-8 * -3);
+        expect(multiply(-12, -10)).to.equal(-12 * -10);
+        expect(multiply(-22, -3)).to.equal(-22 * -3);
+        expect(multiply(-5, -27)).to.equal(-5 * -27);
+      });
+
+      it('should return the product of mixed positive and negative integers', function() {
+        expect(multiply(-79, 82)).to.equal(-79 * 82);
+        expect(multiply(79, -82)).to.equal(79 * -82);
+        expect(multiply(-275, 502)).to.equal(-275 * 502);
+        expect(multiply(275, -502)).to.equal(275 * -502);
+        expect(multiply(2, -2)).to.equal(2 * -2);
+        expect(multiply(-8, 3)).to.equal(-8 * 3);
+        expect(multiply(12, -10)).to.equal(12 * -10);
+        expect(multiply(-22, 3)).to.equal(-22 * 3);
+        expect(multiply(5, -27)).to.equal(5 * -27);
+      });
+
       it('should use recursion by calling self', function () {
         var originalMultiply = multiply;
         multiply = sinon.spy(multiply);