build: check order of deps keys in package.json files

Add a new step to `bin/check-package-metadata.js` to ensure that all
public packages list deps in the following order:
1. `peerDependencies`
2. `dependencies
3. `devDependencies`

Signed-off-by: Miroslav Bajtoš <[email protected]>

bin/check-package-metadata.js

@@ -161,6 +161,8 @@ async function checkPkgsPackageJson(packages, rootPkg) {
     if (!isRepositoryDirectoryExist) {
       errors.push(`${p.name} directory doesn't exist in the monorepo`);
     }
+
+    checkDepsOrder(p, pkg, errors);
   }
 
   return errors;
@@ -202,6 +204,30 @@ async function checkPackagesMetadata() {
   }
 }
 
+function checkDepsOrder(lernaPkg, pkgJson, errors) {
+  const actualOrder = Object.keys(pkgJson).filter(k =>
+    ['dependencies', 'devDependencies', 'peerDependencies'].includes(k),
+  );
+
+  const expectedOrder = [
+    'peerDependencies',
+    'dependencies',
+    'devDependencies',
+  ].filter(k => actualOrder.includes(k));
+
+  const actualStr = actualOrder.join(' ');
+  const expectedStr = expectedOrder.join(' ');
+
+  if (actualStr !== expectedStr) {
+    const pkgPath = path.relative(lernaPkg.rootPath, lernaPkg.location);
+    errors.push(
+      `${pkgPath}/package.json has incorrect order of keys.\n` +
+        `  Actual:   ${actualStr}\n` +
+        `  Expected: ${expectedStr}`,
+    );
+  }
+}
+
 module.exports = checkPackagesMetadata;
 
 runMain(module, checkPackagesMetadata);