more tests for blockoperation

.travis.yml

@@ -6,4 +6,5 @@ script:
   - npm install
   - npm run test-coverage
 
-after_success: 'npm run coveralls'
+after_success:
+  - npm run coveralls

src/BlockOperation.js

@@ -15,6 +15,8 @@ class BlockOperation extends Operation {
             }
         } else if (typeof first === 'function') {
             block = first;
+        } else {
+            throw new Error('Wrong arguments passed: missing ID and/or function');
         }
 
         super(id);

tests/BlockOperation.spec.js

@@ -61,6 +61,15 @@ describe('BlockOperation', () => {
             expect(operation.id).toEqual(1);
             expect(runFunction).toHaveBeenCalled();
         }); 
+
+        test('it should throw error if no parameters are passed in', (done) => {
+            try {
+                const operation = new BlockOperation();
+                fail('should have failed at this point');
+            } catch (e) {
+                done();
+            }
+        }); 
     });
 
     describe('function start', () => {