I have a macro like:
(defmacro test [x] `"~x")
After running it expands to the following:
=> (test abc)
'~x'
Why doesn't it expand to 'abc'?
What is the correct method to unquote inside a string?
I'm confused why you expected this to work, and I'm unclear what you want. ~ in your example is in a string literal, so it's an ordinary string character, not the ~ operator, the same way that ((fn [x] "x") 5) returns "x" and not "5".
If you want to stringify the model that you're passing into a macro, use str, like this:
hy 1.0a1+114.g2abb33b1 using CPython(default) 3.8.6 on Linux
=> (defmacro test [x] (str x))
<function test at 0x7fe0476144c0>
=> (test abc)
"abc"