Suppose I have a function

```
f(x) = x > 1 ? 0 : x
```

For this, I obtain

```
julia> @code_warntype f(0.2)
MethodInstance for f(::Float64)
from f(x) @ Main REPL[43]:1
Arguments
#self#::Core.Const(f)
x::Float64
Body::Union{Float64, Int64}
```

Now, I want to write an inference unit test, but without being specific about the types in the union. I know that this works:

```
julia> @inferred Union{Float64,Int} f(0.2)
0.2
```

I would like to write something like

```
@inferred (Union{A,B} where {A,B}) f(0.2)
```

with the additional constraint, that `A`

and `B`

are concretely inferred. I wonder if there’s a way to test for that the inferred type is a small union, without specifying the exact types that are to be returned?