function confirmLegacyMergeResult(first, second, expectedResult) {
	const configArray = new ConfigArray(
		{ settings: first },
		{ settings: second },
	);
	const config = configArray.extractConfig("/file");
	const actualResult = config.settings;

	assert.deepStrictEqual(actualResult, expectedResult);
}
This function checks the result of merging two values in eslintrc config.
It uses deep strict equality to compare the actual and the expected results.
This is useful to ensure that the flat config merge logic behaves similarly to the old logic.
When eslintrc is removed, this function and its invocations can be also removed.
@param {Object} [first] The base object.
@param {Object} [second] The overrides object.
@param {Object} [expectedResult] The expected reults of merging first and second values.
@returns {void}