Betterer

Incremental Improvement

August 2021

August 2021

Hi, I'm Craig!

August 2021

August 2021

Legacy

August 2021

Local Maxima

Desired state

Current state

August 2021

Revolution!

August 2021

Branching!

August 2021

Automation

August 2021

Evolutionary Algorithms

August 2021

A genetic representation of the solution domain:

0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
1 0 1 0 1 0 1 0
0 1 1 0 0 0 0 1

0

Chromosome

Population

Gene

Genetic Algorithms

August 2021

A genetic representation of the solution domain:

A fitness function to evaluate the solution:

0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
1 0 1 0 1 0 1 0
0 1 1 0 0 0 0 1
f(chromosome) => score

Genetic Algorithms

August 2021

Termination

0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
1 0 1 0 1 0 1 0
0 1 1 0 0 0 0 1
1 0 1 0 1 0 1 0
0 1 1 0 0 0 0 1

Crossover

1 1 1 1 0 0 0 0
0 0 0 0 1 1 1 1

Offspring

0 0 0 0 1 1 1 0

Mutation

Genetic Algorithms

August 2021

August 2021

Humans

Not obsolete yet!

August 2021

Evolutionary Architecture

August 2021

Evolutionary Migration?

A fitness function to evaluate the solution:

f(codebase) => score

August 2021

Code as data

import { BettererOptionsStart } from './config';
import { createGlobals } from './globals';
import { BettererRunner, BettererRunnerΩ } from './runner';
import { BettererSuiteSummary } from './suite';

// Run betterer in single-run mode:
export async function betterer(
  options: BettererOptionsStart = {}
): Promise<BettererSuiteSummary> {
  initDebug();
  const globals = await createGlobals(options);
  const runner = new BettererRunnerΩ(globals);
  return runner.run(globals.config.filePaths);
}

August 2021

Code as data

August 2021

f(oldScore, newScore) => better | worse | same

A comparison function to track progress:

Better?

f(codebase) => oldScore
f(codebase) => newScore

Old state of the codebase

New state of the codebase

August 2021

Codebase as database?

It has become common to store extra information about a codebase in the repository:

# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
# yarn lockfile v1

"@babel/code-frame@7.12.11":
  version "7.12.11"
  resolved "https://registry.npmjs.org/@babel/code-frame/-/code-...
  integrity sha512-Zt1yodBx1UcyiePMSkWnU4hPqhwq7hGi2nFL1LeA3EUl+...
  dependencies:
    "@babel/highlight" "^7.10.4"
// Jest Snapshot v1, https://goo.gl/fbAQLP
 
exports[`betterer should not stay worse if an update is forced 1`] = `
"// BETTERER RESULTS V2.
exports[\`tsquery no raw console.log\`] = { 
  ...
}
`

August 2021

Evolutionary Migration

A fitness function to evaluate the solution

A comparison function to track progress

A little file to store the results

Betterer

Incremental Improvement

August 2021

Betterer

August 2021

August 2021

// package.json
{
  "name": "@craig/my-very-stable-package",
  "version": "20.2.1",
  "author": "Craig Spence <craigspence0@gmail.com>",
  "description": "Gee I wish this package was a little bit better.",
  "scripts": {
    "betterer": "betterer",
    // ...
  },
  // ...
  "devDependencies": {
    "@betterer/cli": "^5.0.0",
    // ...
  }
}

Initialising

August 2021

// .betterer.ts
export default {
  // Add tests here ☀️
};

Initialising

// .betterer.js
module.exports = {
  // Add tests here ☀️
}

TypeScript by default:

JavaScript if you're into that:

August 2021

August 2021

My First Test

// .betterer.ts
import { BettererTest } from '@betterer/betterer';


export default {
  'migrate JS to TS': () => new BettererTest({
    // ...
  })
};

August 2021

My First Test

// .betterer.ts
import { BettererTest } from '@betterer/betterer';
import glob from 'glob';

export default {
  'migrate JS to TS': () => new BettererTest({
    test: () => glob.sync('**/*.js').length,
    // ...
  })
};

August 2021

My First Test

// .betterer.ts
import { BettererTest } from '@betterer/betterer';
import { BettererConstraintResult } from '@betterer/constraints';
import glob from 'glob';

export default {
  'migrate JS to TS': () => new BettererTest({
    test: () => glob.sync('**/*.js').length,
    constraint: (result: number, expected: number) => {
      if (result < expected) {
        return BettererConstraintResult.better;
      }
      if (result === expected) {
        return BettererConstraintResult.same;
      }
      return BettererConstraintResult.worse;
    }
  })
};

August 2021

My First Test

// .betterer.ts
import { BettererTest } from '@betterer/betterer';
import { smaller } from '@betterer/constraints';
import glob from 'glob';

export default {
  'migrate JS to TS': () => new BettererTest({
    test: () => glob.sync('**/*.js').length,
    constraint: smaller
  })
};

August 2021

August 2021

My First Result

// .betterer.results
// // BETTERER RESULTS V2.
exports[`migrate JS to TS`] = {
  value: `9`
};

This is basically the same things as a Jest snapshot file!

August 2021

August 2021

Workflows

Add to CI pipeline

Add to pre-commit hooks for changed files

Take their changes when merging

August 2021

// cool.js
export function ohBoyILoveJavaScript () {
  console.log(`I'll never change!!!`);
  return [1, 2, 3] + [4, 5, 6];
}

August 2021

August 2021

My First  File Test

// .betterer.ts
import { BettererTest } from '@betterer/betterer';
import { smaller } from '@betterer/constraints';
import glob from 'glob';

export default {
  'migrate JS to TS': () => new BettererTest({
    test: () => glob.sync('**/*.js').length,
    constraint: smaller
  })
};

August 2021

My First  File Test

// .betterer.ts
import { BettererFileTest } from '@betterer/betterer';

export default {
  'migrate JS to TS': () =>
    new BettererFileTest(async (filePaths, fileTestResult) => {
      // ...
      // 
    }).include('**/*.js')
};

August 2021

My First  File Test

// .betterer.ts
import { BettererFileTest } from '@betterer/betterer';
import { promises as fs } from 'fs';

export default {
  'migrate JS to TS': () =>
    new BettererFileTest(async (filePaths, fileTestResult) => {
      await Promise.all(
        filePaths.map(async (filePath) => {
          const fileContents = await fs.readFile(filePath, 'utf8');
          const file = fileTestResult.addFile(filePath, fileContents);
          file.addIssue(0, 1, 'Please use TypeScript!');
        })
      );
    }).include('**/**/*.js')
};

August 2021

August 2021

August 2021

August 2021

// BETTERER RESULTS V2.
exports[`migrate JS to TS`] = {
  value: `{
    "index.js:2978447364": [
      [0, 0, 1, "Please use TypeScript!", "177600"]
    ],
    "cool.js:3542870298": [
      [0, 0, 1, "Please use TypeScript!", "287364"]
    ],
    "amazing.js:8762519887": [
      [0, 0, 1, "Please use TypeScript!", "726351"]
    ],
    //...
    // 10 total issues:
  }`
};

August 2021

August 2021

// .betterer.ts
import { BettererFileTest } from '@betterer/betterer';
import { promises as fs } from 'fs';

export default {
  'migrate JS to TS': () =>
    new BettererFileTest(async (filePaths, fileTestResult) => {
      await Promise.all(
        filePaths.map(async (filePath) => {
          const fileContents = await fs.readFile(filePath, 'utf8');
          const file = fileTestResult.addFile(filePath, fileContents);
          file.addIssue(0, 1, 'Please use TypeScript!');
        })
      );
    })
    .include('**/**/*.js')
    .deadline('2021/12/31')
};

My First  Deadline

August 2021

August 2021

// BETTERER RESULTS V2.
exports[`migrate JS to TS`] = {
  value: `{
    "index.js:2978447364": [
      [0, 0, 1, "Please use TypeScript!", "177600"]
    ],
    "boo.js:1827649983": [
      [0, 0, 1, "Please use TypeScript!", "298736"]
    ],
    "gross.js:1872646688": [
      [0, 0, 1, "Please use TypeScript!", "009726"]
    ],
    //...
    // 8 total issues:
  }`
};

August 2021

More tests!

August 2021

Built in tests!

// .betterer.ts
import { eslint } from '@betterer/eslint';

import { regexp } from '@betterer/regexp';

import { stylelint } from '@betterer/stylelint';

import { tsquery } from '@betterer/tsquery';

import { typescript } from '@betterer/typescript';

Betterer

Help?!

August 2021

Thanks!

August 2021

Betterer: Incremental Improvement

By Craig Spence

Betterer: Incremental Improvement

  • 338