Traction testing
 

The last couple of days have been mild, a couple of degrees above freezing, with a bit of rain and wet snow. Today, however, it is a couple of degrees below freezing and not about to warm up so the sidewalks are a bit (or more) slippery, despite the sand laid down on them. I was walking in today and as I walked on what appeared to be slippery ice, I got into the habit of twisting my foot a touch (as if rubbing out a cigarette on the sidewalk) to test my traction and it was quite useful to know what the traction was like, especially on a section of about 30m/yd that appeared to be glare ice.

When riding, does anyone do something similar, weave the front wheel back and forth a bit on potentially slippery sections to both test the slipperiness and/or force the studs on the sides of the tire to grab a bit?

I don't. I try to avoid the bike when it's icy but last monday (the 6th) I hit a 5-6 kms stretch of solid ice on my way to work and there was nothing to do about it. I fell 4-5 times ( I was going very slow so no harms done) So I had to deflate my tires, they're homemade studded tires so when they're fully inflated the studs don't touch the ground, Once I deflated my tires to about 25-30 psi I had better grip but it still felt very hazardous, I didn't feel like weaving the front Wheel at all.

When I'm not sure about it I ride as if it's solid ice.

I absolutely do not try to break my front tire loose swerving around on purpose !!! Just a touch of the rear brake and feeling how much traction there is before the rear wheel starts to skid is all that is needed to "test" and I do do that quite often. Recovering from a rear wheel skid without going down is nothing and just involves letting off the brake and re-balancing and steering out of the skid; way better then trying to recovering from your front tire going squirrelly on you and out to one side in a slide, that's potential face plant territory !!! At least that how it be with a two wheel front and rear wheel bicycle, on a trike with three point triangular stability its a different story.

On December 23 od 2012 my bike's tire slipped on a small patch of ice. I went down hard and broke my hip. On Christmas eve I was in the hospital getting a total hip replacement.
The only bike I ever ride on ice anymore has studded tires, even if there is the slightest chance of running into ice.