flatten-releases.ts

// This function takes in changesets and returns one release per
// package listed in the changesets

import { NewChangeset } from "@changesets/types";
import { Package } from "@manypkg/get-packages";
import { InternalRelease } from "./types";

export default function flattenReleases(
  changesets: NewChangeset[],
  packagesByName: Map<string, Package>,
  ignoredPackages: Readonly<string[]>
): Map<string, InternalRelease> {
  let releases: Map<string, InternalRelease> = new Map();

  changesets.forEach(changeset => {
    changeset.releases
      // Filter out ignored packages because they should not trigger a release
      // If their dependencies need updates, they will be added to releases by `determineDependents()` with release type `none`
      .filter(({ name }) => !ignoredPackages.includes(name))
      .forEach(({ name, type }) => {
        let release = releases.get(name);
        let pkg = packagesByName.get(name);
        if (!pkg) {
          throw new Error(
            `"${changeset.id}" changeset mentions a release for a package "${name}" but such a package could not be found.`
          );
        }
        if (!release) {
          release = {
            name,
            type,
            oldVersion: pkg.packageJson.version,
            changesets: [changeset.id]
          };
        } else {
          if (
            type === "major" ||
            ((release.type === "patch" || release.type === "none") &&
              (type === "minor" || type === "patch"))
          ) {
            release.type = type;
          }
          // Check whether the bumpType will change
          // If the bumpType has changed recalc newVersion
          // push new changeset to releases
          release.changesets.push(changeset.id);
        }

        releases.set(name, release);
      });
  });

  return releases;
}