fix: support npm 12 pack JSON output

tests/pack-result.d.ts

@@ -0,0 +1,5 @@
+export interface PackRecord {
+  files: Array<{ path: string }>;
+}
+
+export function readPackRecord(result: unknown): PackRecord;

tests/pack-result.js

@@ -0,0 +1,27 @@
+/** @typedef {{ files: Array<{ path: string }> }} PackRecord */
+
+/** Normalize the array and name-keyed object shapes used by npm pack --json. */
+export function readPackRecord(result) {
+  const records = Array.isArray(result)
+    ? result
+    : result !== null && typeof result === "object"
+      ? Object.values(result)
+      : [];
+
+  if (records.length !== 1)
+    throw new Error(`Expected one packed artifact, received ${records.length}.`);
+
+  const record = records[0];
+  if (
+    record === null ||
+    typeof record !== "object" ||
+    !Array.isArray(record.files) ||
+    !record.files.every(
+      (file) => file !== null && typeof file === "object" && typeof file.path === "string",
+    )
+  ) {
+    throw new Error("npm pack returned an invalid artifact record.");
+  }
+
+  return /** @type {PackRecord} */ (record);
+}

tests/pack-result.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+import { readPackRecord } from "./pack-result.js";
+
+const record = { filename: "package.tgz", files: [{ path: "dist/index.js" }] };
+
+describe("npm pack JSON normalization", () => {
+  it.each([[record], { "@askrjs/node": record }])(
+    "should read one artifact from the supported npm result shape",
+    (result) => {
+      expect(readPackRecord(result)).toBe(record);
+    },
+  );
+
+  it.each([[], [record, record], {}, null, "invalid"])(
+    "should reject a result without exactly one artifact",
+    (result) => {
+      expect(() => readPackRecord(result)).toThrow(/Expected one packed artifact/);
+    },
+  );
+
+  it("should reject malformed artifact records", () => {
+    expect(() => readPackRecord([{ files: [{ path: 1 }] }])).toThrow(
+      "npm pack returned an invalid artifact record.",
+    );
+  });
+});

tests/package-artifacts.js

@@ -1,13 +1,16 @@
 import { execFileSync } from "node:child_process";
 import { readFileSync } from "node:fs";
 import { dirname, join, normalize } from "node:path";
+import { readPackRecord } from "./pack-result.js";
 
 const npmCli = process.env.npm_execpath;
 if (!npmCli) throw new Error("npm_execpath is unavailable; run this check through npm");
-const result = JSON.parse(
-  execFileSync(process.execPath, [npmCli, "pack", "--ignore-scripts", "--dry-run", "--json"], {
-    encoding: "utf8",
-  }),
+const result = readPackRecord(
+  JSON.parse(
+    execFileSync(process.execPath, [npmCli, "pack", "--ignore-scripts", "--dry-run", "--json"], {
+      encoding: "utf8",
+    }),
+  ),
 );
 
 const manifest = JSON.parse(readFileSync("package.json", "utf8"));
@@ -17,11 +20,7 @@ if (JSON.stringify(dependencies) !== JSON.stringify(allowedDependencies)) {
   throw new Error(`Unexpected production dependencies: ${dependencies.join(", ")}`);
 }
 
-if (result.length !== 1) {
-  throw new Error(`Expected one packed artifact, received ${result.length}.`);
-}
-
-const packedFiles = new Set(result[0].files.map(({ path }) => normalize(path)));
+const packedFiles = new Set(result.files.map(({ path }) => normalize(path)));
 for (const required of [
   "LICENSE",
   "README.md",
@@ -45,7 +44,7 @@ for (const file of packedFiles) {
 }
 const sourceMappingPattern = /[#@]\s*sourceMappingURL=([^\s*]+)/gu;
 
-for (const file of result[0].files) {
+for (const file of result.files) {
   if (!/\.(?:css|d\.ts|js)$/u.test(file.path)) continue;
 
   const source = readFileSync(file.path, "utf8");