portainer/app/react/components/form-components/yup-file-validation.ts

import { mixed } from 'yup';
import { MixedSchema } from 'yup/lib/mixed';

type FileSchema = MixedSchema<File | undefined>;

export function file(): FileSchema {
  return mixed();
}

export function withFileSize(fileValidation: FileSchema, maxSize: number) {
  return fileValidation.test(
    'fileSize',
    'Selected file is too big.',
    validateFileSize
  );

  function validateFileSize(file?: File) {
    if (!file) {
      return true;
    }

    return file.size <= maxSize;
  }
}