How well does that movie you head out to see on Labour Day depict LGBT characters? Admittedly the Russo Test is not as snappy as the Bechdel test, but worth perusing:
1. The film contains a character that is identifiably lesbian, gay, bisexual, and/or transgender.
2. That character must not be solely or predominantly defined by their sexual orientation or gender identity. I.E. they are made up of the same sort of unique character traits commonly used to differentiate straight characters from one another.
3. The LGBT character must be tied into the plot in such a way that their removal would have a significant effect. Meaning they are not there to simply provide colorful commentary, paint urban authenticity, or (perhaps most commonly) set up a punchline. The character should matter.
Feminist Philosophers 
Hm. Must it revolve around identity? The Bechdel test was about what *happens* (and it’s so powerful because it asks so little!). Film and other art can illuminate non-heteronormative experiences and interactions in a wide variety of ways. Marking the identity of key character(s) is just one of them.
Criteria 2 and 3 seem like a good minimum standard to help filmmakers avoid shallow and stereotype-reliant LGBT characters, but I’m not sure that a test analogous to the Bechdel test is the best way to think about promoting these standards. The Bechdel test sets expectations which would improve (both ethically and aesthetically) almost all narrative films, so it makes sense to ask of any given film “Does this movie pass the Bechdel test?” Not passing the Bechdel test is almost always a failing of a film.
But I don’t think the Russo test is analogous. In part this is because many films have very few characters who are “tied into the plot in such a way that their removal would have a significant effect.” If we were to make sure that at least one of these characters was LGBT in every narrative film, LGBT characters would be drastically overrepresented on screen relative to the composition of the general population. Given the positive effect that sympathetic artistic representations of disadvantaged groups can have on culture perceptions, some overrepresentation is probably a good thing, but probably not as much as the Russo Test would require.
More importantly, there are many films where sexual orientation and gender identity are irrelevant to either plot or character development, and I agree with Elise that it might not always be necessary to make a character’s identity explicit. It seems to me that if the Russo Criteria were met in every film, it could even be counterproductive. If in *every* film the filmmakers conspicuously called attention to the sexual identity of characters whose contributions and complexity would otherwise stand on their own, it sends a message that we need to know a person’s sexual orientation and gender identity in order to fully appreciate them. This is wrong. In the actual world, many people prefer to keep the details of their sexual identity and preferences private, and we can fully appreciate the character and contributions of those individuals without digging into the details of their love life. Consistent with that fact, it seems to me that in some films where LGBT status is irrelevant, the filmmaker need not call special attention characters’ sexual/gender identity. This is not to say that there aren’t many films which could be enriched by a nuanced portrayal of LGBT individuals, only that not all films need to explore the love lives of their characters. In other words, the Russo test is better seen as a set of criteria for the portrayal of LGBT characters when they appear, while the Bechdel test applies to nearly every narrative film.
The problem with not “making a character’s identity explicit” is that it causes the audience to assume that the character is really just straight/cis/totally-normal-like-them. Unless you do something really silly, like announcing a character’s sexual identity after the fact (Dumbledore!), then you are left with either allowing the audience to assume that none of your characters are LGBT or conspicuously mentioning it even when not central to the plot. I imagine this is an even worse problem for eg the representation of people who are asexual, since it is kinda hard to shoehorn the fact that you lack an interest in sex in the middle of a conversation without being “conspicuous”.
If we are at all concerned with the representation of these sorts of people in film, then I don’t see why being conspicuous about it is such a big deal. Maybe before considering what the consequences of weirdly apocalyptic scenarios like “the Russo Criteria [being] met in every film” are (as if that were the intention! I’m pretty sure GLAAD is aware that the LGBT population is smaller than the population of women), it would be better if we looked at the consequences of it being met in the last film you watched.