You know things are going well for Roku (ROKU -0.35%) investors when the stock is one of the few names to move higher during Monday's brutal sell-off, but that's just the way things have gone for its shareholders this year. Roku stock has more than tripled -- up 235% -- in 2019, but a major test awaits later this week.

The video-streaming pioneer reports its second-quarter results after the market close on Wednesday, and expectations are admittedly high. Analysts see revenue soaring 43% to hit $224.2 million, and that's a pretty heady clip for a company that grew its top line at a mere 19% pace the quarter before it went public two years ago. The Roku revenue mix has shifted dramatically since then, as high-margin and fast-growing platform revenue has taken over as the lead driver from the low-margin and slower-growing hardware revenue that once defined the media player.

Roku has transformed itself into a market darling, but with that glow-up comes the lofty expectations for it to deliver in this week's telltale financial release. 

The Roku TV operating system running on a TCL smart television

Image source: Roku.

A streaming star is born

Roku has come a long way in just two years of public trading. A dominant 54% of its top-line results in the second quarter of 2017 came from the sale of its iconic streaming devices that attach to your TV like a leech to educate your dumb TV into being a smart one. Streaming device hardware is a cutthroat business with crummy margins, but it was the only way for Roku to get its operating system's foot into your living room until it started brokering deals with smart television manufacturers to be the default gateway to all things streaming. 

Player revenue is now down to roughly a third of the revenue mix, as platform revenue has blossomed to account for 65% of Roku's business in its most recent report. There are now 29.1 million streaming users on Roku, more than doubling over the past two years. Platform revenue has nearly quadrupled in that time because average revenue per user has nearly doubled, going from a trailing-12-month run rate of $10.05 to $19.06 in those two years. 

Users -- and by users we're talking about accounts, as in entire families -- are growing more comfortable with streaming over traditional broadcast television experiences. It also only helps Roku that so many compelling services are rolling out, making its starring role as a streaming service sommelier that much more lucrative. Roku users are spending an average of more than three hours a day on the platform, and that's a lot of ad revenue, service sign-up referral fees, and royalties to collect. 

Whether Roku continues to dominate this booming market or gets gobbled up by an envious tech or media giant at a juicy premium, it seems like a win-win for investors at this point. The one thing that would naturally derail this monster stock is if usage trends start going the other way. Roku's report on Wednesday and any potential insight into the future will dictate whether or not one of this year's hottest stock keeps heating up.