tests(firestore-send-email): refactor tests

Author: HassanBahati

firestore-send-email/functions/__tests__/validation.test.ts

@@ -615,7 +615,7 @@ describe("validatePayload", () => {
         };
         expect(() => validatePayload(invalidPayload)).toThrow(ValidationError);
         expect(() => validatePayload(invalidPayload)).toThrow(
-          "Invalid message configuration: Field 'message.attachments' must be an array"
+          "Invalid message configuration: Field 'message.attachments' must be an array. If you have a single attachment object, wrap it in an array (e.g., [{ filename: '...', path: '...' }])"
         );
       });
     });

firestore-send-email/functions/src/validation.ts

@@ -193,6 +193,13 @@ function formatZodError(
           return `Field '${path}' must be a string`;
         }
         if (issue.expected === "array") {
+          if (issue.message && !issue.message.startsWith("Expected")) {
+            const customMessage = issue.message.replace(
+              /Field 'attachments'/g,
+              `Field '${path}'`
+            );
+            return customMessage;
+          }
           return `Field '${path}' must be an array`;
         }
         if (issue.expected === "object") {