function testOp(browser, opName, input, output, args=[]) {
    bakeOp(browser, opName, input, args);
    utils.expectOutput(browser, output, true);
}
@function
Clears the current recipe and tests a new operation.

@param {Browser} browser - Nightwatch client
@param {string|Array<string>} opName - name of operation to be tested, array for multiple ops
@param {string} input - input text
@param {string|RegExp} output - expected output
@param {Array<string>|Array<Array<string>>} [args=[]] - arguments, nested if multiple ops