Churn report example

gistfile1.txt

import { createProjectGraphAsync } from '@nx/devkit';
import { execSync } from 'node:child_process';

export async function churnGenerator(
) {
  const graph = await createProjectGraphAsync();
  const projects: Record<string, { ancestors: number; affected: number }> = {};

  console.log('Calculating ancestors');
  for (const project in graph.dependencies) {
    graph.dependencies[project]
      .filter(
        (project) =>
          !project.target.startsWith('npm') &&
          graph.nodes[project.target].type === 'lib'
      )
      .forEach((dependency) => {
        if (projects[dependency.target] !== undefined) {
          projects[dependency.target].ancestors++;
        } else {
          projects[dependency.target] = {
            ancestors: 1,
            affected: 0,
          };
        }
      });
  }
  console.log(projects);

  console.log('Calculating how often projects were affected');

  const gitOutput = execSync(
    'git log --pretty=format:"%H" --since=15.days'
  ).toString('utf-8');
  const hashes = gitOutput.split('\n');
  const pairedHashes = hashes.reduce<Array<[string, string] | [string]>>(
    (acc, cur) => {
      const lastTuple = acc.pop();

      if (!lastTuple) {
        acc.push([cur]);
      } else if (lastTuple.length === 1) {
        acc.push([...lastTuple, cur]);
      } else if (lastTuple.length === 2) {
        acc.push(lastTuple);
        acc.push([lastTuple[1], cur]);
      }
      return acc;
    },
    []
  );

  pairedHashes.forEach((pairedHash) => {
    const affectedOutput = execSync(
      `yarn nx show projects --affected --head=${pairedHash[0]} --base=${pairedHash[1]}`
    ).toString('utf-8');
    const affected = affectedOutput.split('\n').slice(1, -1);
    affected.forEach((project) => {
      if (projects[project] !== undefined) {
        projects[project].affected++;
      }
    });
  });

  const sortedProjects: { project: string; score: number }[] = [];

  for (const project in projects) {
    sortedProjects.push({
      project,
      score: projects[project].affected * projects[project].ancestors,
    });
  }

  sortedProjects.sort((a, b) => b.score - a.score);

  console.log(sortedProjects);
}

export default churnGenerator;