Fix typo in promote, add tests (#6)

Author: mtfishman

Project.toml

@@ -1,7 +1,7 @@
 name = "UnspecifiedTypes"
 uuid = "42b3faec-625b-4613-8ddc-352bf9672b8d"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.1.1"
+version = "0.1.2"
 
 [compat]
 julia = "1.10"

src/unspecifiedzero.jl

@@ -32,6 +32,6 @@ Base.:/(::Number, ::UnspecifiedZero) = throw(DivideError())
 Base.:/(::UnspecifiedZero, ::UnspecifiedZero) = throw(DivideError())
 Base.:-(::UnspecifiedZero) = UnspecifiedZero()
 
-Base.promote_rule(::Type{<:UnspecifiedZero}, t::Type) = t2
+Base.promote_rule(::Type{<:UnspecifiedZero}, t::Type) = t
 Base.promote_rule(::Type{<:UnspecifiedZero}, ::Type{<:UnspecifiedZero}) = UnspecifiedZero
 Base.promote_type(::Type{<:Complex{<:UnspecifiedZero}}, t::Type) = complex(t)

test/Project.toml

@@ -3,6 +3,7 @@ Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UnspecifiedTypes = "42b3faec-625b-4613-8ddc-352bf9672b8d"
 
 [compat]
 Aqua = "0.8.9"

test/test_basics.jl

@@ -0,0 +1,16 @@
+using UnspecifiedTypes: UnspecifiedZero
+using Test: @testset, @test
+
+@testset "UnspecifiedTypes (eltype=$elt)" for elt in (
+  Float32, Float64, Complex{Float32}, Complex{Float64}
+)
+  for x in (elt(2) + UnspecifiedZero(), UnspecifiedZero() + elt(2))
+    @test x isa elt
+    @test x === elt(2)
+  end
+
+  for x in (elt(2) * UnspecifiedZero(), UnspecifiedZero() * elt(2))
+    @test x isa UnspecifiedZero
+    @test x === UnspecifiedZero()
+  end
+end