Betterer

Incremental Improvement

@phenomnominal

September 2021

@phenomnominal

September 2021

@phenomnominal

Hi, I'm Craig!

September 2021

twitter.com/phenomnominal

linkedin.com/in/craig-spence

github.com/phenomnomnominal

@phenomnominal

Legacy

September 2021

@phenomnominal

Local Maxima

Desired state

Current state

September 2021

@phenomnominal

September 2021

Why don't we rewrite the whole thing?!

@phenomnominal

Revolution!

September 2021

@phenomnominal

Revolution...

September 2021

@phenomnominal

Branching!

September 2021

@phenomnominal

Branching...

September 2021

// eslint-disable-next-line @typescript-eslint/no-explicit-any
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
// eslint-disable-next-line @typescript-eslint/no-explicit-any
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@phenomnominal

Automation

September 2021

@phenomnominal

Humans

Not obsolete yet!

September 2021

@phenomnominal

Buttons

September 2021

<button 
  class="button button--green">
  Continue
</button>

<button 
  class="button button--red">
  Cancel
</button>

<button 
  class="button button--success">
  Continue
</button>

<button 
  class="button button--danger">
  Cancel
</button>

@phenomnominal

September 2021

Inspiration

@phenomnominal

Evolutionary Architecture

September 2021

@phenomnominal

Evolutionary Algorithms

September 2021

@phenomnominal

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

Chromosome

Population

Gene

Genetic Algorithms

September 2021

@phenomnominal

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

September 2021

@phenomnominal

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

September 2021

@phenomnominal

Tetris

September 2021

@phenomnominal

September 2021

@phenomnominal

Evolutionary Migration?

A fitness function to evaluate the solution:

f(codebase) => score

September 2021

@phenomnominal

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);
}

September 2021

@phenomnominal

Code as data

September 2021

ts(codebase) => nCompilerErrors

eslint(codebase) => nLintErrors

axe(codebase) => nA11yErrors

jest(codebase) => coverage%

@phenomnominal

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

September 2021

@phenomnominal

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\`] = { 
  ...
}
`

September 2021

@phenomnominal

Evolutionary Migration

A fitness function to evaluate the solution

A comparison function to track progress

A little file to store the results

September 2021

Betterer

Incremental Improvement

@phenomnominal

September 2021

@phenomnominal

September 2021

phenomnomnominal.github.io/betterer

@phenomnominal

// 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

September 2021

@phenomnominal

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

Initialising

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

TypeScript by default:

JavaScript if you're into that:

September 2021

@phenomnominal

September 2021

@phenomnominal

My First Test

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


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

September 2021

@phenomnominal

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,
    // ...
  })
};

September 2021

@phenomnominal

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;
    }
  })
};

September 2021

@phenomnominal

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
  })
};

September 2021

@phenomnominal

September 2021

@phenomnominal

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!

September 2021

@phenomnominal

September 2021

@phenomnominal

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

September 2021

@phenomnominal

September 2021

@phenomnominal

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
  })
};

September 2021

@phenomnominal

My First File Test

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

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

September 2021

@phenomnominal

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')
};

September 2021

@phenomnominal

September 2021

@phenomnominal

September 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"]
    ],
    //...
    // 9 total issues:
  }`
};

@phenomnominal

Betterer VS Code Extension

September 2021

@phenomnominal

September 2021

@phenomnominal

// 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:
  }`
};

September 2021

@phenomnominal

September 2021

@phenomnominal

// .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

September 2021

@phenomnominal

September 2021

@phenomnominal

// 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:
  }`
};

September 2021

@phenomnominal

More tests!

September 2021

@phenomnominal

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';

September 2021

Betterer

Help?!

@phenomnominal

September 2021

Questions?

@phenomnominal

September 2021

twitter.com/phenomnominal