fix: add tests for package.json loading

Author: mnahkies

packages/openapi-code-generator/src/core/file-system/node-fs-adaptor.ts

@@ -17,7 +17,11 @@ export class NodeFsAdaptor implements IFsAdaptor {
       const stat = await fs.stat(path)
       return stat.isFile()
     } catch (err) {
-      if (err instanceof Error && Reflect.get(err, "code") === "ENOENT") {
+      if (
+        typeof err === "object" &&
+        err !== null &&
+        Reflect.get(err, "code") === "ENOENT"
+      ) {
         return false
       }
       throw err

packages/openapi-code-generator/src/core/loaders/package.json.loader.spec.ts

@@ -0,0 +1,33 @@
+import path from "node:path"
+import {describe, expect, it} from "@jest/globals"
+import {NodeFsAdaptor} from "../file-system/node-fs-adaptor"
+import {loadPackageJson} from "./package.json.loader"
+
+describe("core/loaders/package.json.loader", () => {
+  const fsAdaptor = new NodeFsAdaptor()
+
+  it("should load the nearest package.json (commonjs)", async () => {
+    const actual = await loadPackageJson(__dirname, fsAdaptor)
+
+    expect(actual).toEqual({
+      type: "commonjs",
+    })
+  })
+
+  it("should load the nearest package.json (esm)", async () => {
+    const actual = await loadPackageJson(
+      path.join(__dirname, "../../../../../e2e"),
+      fsAdaptor,
+    )
+    expect(actual).toEqual({
+      type: "module",
+    })
+  })
+
+  it("should default to commonjs if no package.json is found", async () => {
+    const actual = await loadPackageJson("/tmp/foo/bla", fsAdaptor)
+    expect(actual).toEqual({
+      type: "commonjs",
+    })
+  })
+})

packages/openapi-code-generator/src/core/loaders/package.json.loader.ts

@@ -1,6 +1,7 @@
 import json5 from "json5"
 import {z} from "zod/v4"
 import type {IFsAdaptor} from "../file-system/fs-adaptor"
+import {logger} from "../logger"
 import {loadFileUp} from "./utils"
 
 const schema = z.object({
@@ -11,9 +12,14 @@ export async function loadPackageJson(
   outputPath: string,
   fsAdaptor: IFsAdaptor,
 ) {
-  const packageJson = json5.parse(
-    (await loadFileUp("package.json", outputPath, fsAdaptor)) ?? "{}",
-  )
+  let rawJson = await loadFileUp("package.json", outputPath, fsAdaptor)
+
+  if (!rawJson) {
+    logger.warn("no package.json found, using defaults")
+    rawJson = "{}"
+  }
+
+  const packageJson = json5.parse(rawJson)
 
   return schema.parse(packageJson)
 }