DefaultValue not working

[safiresh]

const Ajv = require('ajv');
const ajv = new Ajv({
  allErrors: true,
  format: 'full',
  useDefaults: true,
  coerceTypes: false,
  errorDataPath: 'property',
  sourceCode: false,
});
require('ajv-merge-patch')(ajv);
const base = {
  type: 'object',
  properties: {
    operation: {
      type: 'string',
      enum: ['create', 'update', 'delete'],
    },
    id: {
      type: 'string',
    },
  },
};

const schema = {
  $merge: {
    source: base,
    with: {
      type: 'object',
      properties: {
        test: {
          type: 'integer',
          default: 0,
        },
      },
    }
  }
};

const params = {
  operation: 'delete'
};
const validate = ajv.compile(schema);
const isValidParams = validate(params);
console.log(params);

Actual :
{ operation: 'delete' }
Expected :
{ operation: 'delete' , test: 0}

[nick4fake]

@epoberezkin are there any workarounds for it? So far even defining default in "with" is simply ignored.