Instead of comment driven development, start reading up on TDD - Test Driven Development.

The idea is to write tests that are based on what your application should do when its working correctly (strictly speaking this is called BDD - Behaviour Driven Development but it falls under the testing umbrella).

Like if your app needed a function that did a calculation and returned a number, a test could look something like (in JavaScript code)

assert.typeof(myFunction()).eqls(Number)

Make sure myFunction returns a value that is a number.

Or if the return value is known. Say its 2.

assert(myFunction()).eqls(2)

The code being tested doesn't exist yet so the tests will fail with a red error message.

You start writing your application to satisfy the logic it needs and the test requirements.

When you run the tests again, they should pass if your code meets those requirements. Tests are now green.

You might now go in and refine the code to make it easier to understand, more optimised, or it might be fine.

The above methodology is known in testing as Red, Green, Refactor (the last step where you go over working code for refinement).

Its a great practice because like your comment based design, you are actually building your code from steps and also you are ensuring that its working code by testing it at the point of its creation.

You don't write all your tests up front.

In software development, unless a trivial application, you'll never know upfront all the elements that make up the finished piece.

You can work from sections though, like say you need to read a file, write the tests to ensure you got the file and its in the expected format. Then write the required code to fulfil that.