Have some fun with Yarn constraints (#438)

I recently learned about Yarn constraints (https://yarnpkg.com/features/constraints), so I've been yearning for a chance to try them.

Author: miorel

package.json

@@ -29,6 +29,7 @@
   },
   "devDependencies": {
     "@code-chronicles/eslint-config": "workspace:*",
+    "@yarnpkg/types": "4.0.0",
     "eslint": "9.11.0",
     "husky": "9.1.6",
     "lint-staged": "15.2.10",

yarn.config.cjs

@@ -1,7 +1,55 @@
-module.exports = {
+const { defineConfig } = require("@yarnpkg/types");
+
+module.exports = defineConfig({
   async constraints({ Yarn }) {
+    const rootWorkspace = Yarn.workspace({ cwd: "." });
+    if (rootWorkspace == null) {
+      Yarn.workspace().error("Didn't find a root workspace?!");
+      return;
+    }
+
+    // Use ESM everywhere.
     for (const workspace of Yarn.workspaces()) {
       workspace.set("type", "module");
     }
+
+    // Set a consistent repository for all workspaces.
+    if (rootWorkspace.manifest.repository == null) {
+      rootWorkspace.error("Missing repository specification!");
+    }
+    for (const workspace of Yarn.workspaces()) {
+      if (workspace.cwd !== ".") {
+        workspace.set("repository.directory", workspace.cwd);
+        workspace.set(
+          "repository.type",
+          rootWorkspace.manifest.repository.type,
+        );
+        workspace.set("repository.url", rootWorkspace.manifest.repository.url);
+      } else {
+        workspace.unset("repository.directory");
+      }
+    }
+
+    // Expect each workspace to either have a license or be private.
+    for (const workspace of Yarn.workspaces()) {
+      if (workspace.manifest.license == null && !workspace.manifest.private) {
+        // Don't default since we want a human to make the call.
+        workspace.error("Missing license for non-private workspace!");
+      }
+    }
+
+    // Expect each workspace to specify a version, except for the root.
+    for (const workspace of Yarn.workspaces()) {
+      if (workspace.cwd !== ".") {
+        workspace.set("version", workspace.manifest.version ?? "0.0.1");
+      } else {
+        workspace.unset("version");
+      }
+    }
+
+    // Explicitly specify whether the workspace is private or not.
+    for (const workspace of Yarn.workspaces()) {
+      workspace.set("private", !!workspace.manifest.private);
+    }
   },
-};
+});