fix: tighten isFile to reject partial schemas

Author: kimon-satan

package-lock.json

@@ -13,4 +13,15 @@ describe("isFile", () => {
     expect(isFile(z.string())).toBe(false);
     expect(isFile(z.number())).toBe(false);
   });
+
+  it("should return false for an object schema without required fields", () => {
+    const objectSchema = z
+      .object({
+        name: z.string(),
+        age: z.number(),
+      })
+      .partial();
+    const result = isFile(objectSchema);
+    expect(result).toBe(false);
+  });
 });

src/utils/zod-schema.test.ts

@@ -1,6 +1,13 @@
 import type { ZodType } from "zod";
 
 export function isFile(schema: ZodType<unknown>) {
-  const result = schema.safeParse(new File([], "nothing.txt"));
-  return result.success;
+  // Test that it accepts a File AND rejects a plain object
+  const file = new File([], "nothing.txt");
+  const plainObject = { name: "test", size: 0 };
+
+  const fileResult = schema.safeParse(file);
+  const objectResult = schema.safeParse(plainObject);
+
+  // Should accept File but reject plain object (if it's truly a File schema)
+  return fileResult.success && !objectResult.success;
 }