inductive.js

This is an experimental library which uses unit tests to autogenerate working code.

Example:

specify('myFunc',
  given(2, shouldReturn(4)),
  given(3, shouldReturn(9)),
  use('*'));

/* This code is autogenerated:
function myFunc(arg0) {
  return (arg0 * arg0)
}
*/

As the unit tests change, the output code automatically changes:

specify('myFunc',
  given(2, shouldReturn(8)),  // 4 changed to 8
  given(3, shouldReturn(27)), // 9 changed to 27
  use('*'))

/* This code is autogenerated:
function myFunc(arg0) {
  return (arg0 * (arg0 * arg0))
}
*/

It works by doing a breadth-first, brute force search over strongly typed abstract syntax trees and returns the first one that satisfies the unit tests.

The use function gives inductive.js building blocks to choose from as it searches for a solution. In this case we've given it the multiplication operator. It combines these building blocks with the function's arguments to create candidate test programs.

Ideally, we wouldn't need a use function, but the search space of all possible JavaScript programs is too large to be practical.

Still, even with this limitation, inductive.js has benefits over conventional unit tests:

• We only need to write and maintain one version of the code, instead of having to simultaneously update code and tests whenever we make a change.

• Inductively generated code is generally more reliable because we have a programmatic guarantee that we haven't included code that isn't related to a test.

Inductive.js can handle non-toy problems as well. For example, I/O operations like AJAX are handled using mocks. Additionally, specifications are composable, so inductive.js can generate programs of any size or complexity.

Value

The main value of inductive.js is software verification. The solver uses a strong type system that all programs runs through as they are generated.

Additionally, inductive.js code is immutable by default, which decreases the likelihood of software errors.

Finally, all code is tied programmatically to unit tests. This provides a much stronger guarantee than conventionally-tested code.

Quick Start

First:

npm install inductive.js

Then create a file called helloworld.i.js:

// Load the DSL:
require('inductive.js').globals()

// Specify our program:
var helloWorld = specify('helloWorld',
  givenNoArgs(
    shouldReturn(undefined),
    mock('console.log',
      verify('hello world'))),
  use(
    'console.log',
    value('hello world')))

run(helloWorld)

// Generate the .js file:
saveAll()

Run the spec:

node helloworld.i.js

This autogenerates the code:

function helloWorld() {
  return console.log('hello world');
}

helloWorld();

We can now run the auto-generated program:

node helloworld.js

Docs

Docs are forthcoming. In the meantime, the testSolves.i.js file contains many examples. The buildingBlocks.js file contains the default list of building blocks that you can include with the use command.

License

MIT