fix empty bug

Project.toml

@@ -1,7 +1,7 @@
 name = "TensorKit"
 uuid = "07d1fe3e-3e46-537d-9eac-e9e13d0d4cec"
 authors = ["Jutho Haegeman"]
-version = "0.12.1"
+version = "0.12.2"
 
 [deps]
 HalfIntegers = "f0d1745a-41c9-11e9-1dd9-e5d34d218721"

src/fusiontrees/iterator.jl

@@ -5,7 +5,12 @@ function fusiontrees(uncoupled::NTuple{N,I}, coupled::I,
                      isdual::NTuple{N,Bool}) where {N,I<:Sector}
     return FusionTreeIterator{I,N}(uncoupled, coupled, isdual)
 end
-function fusiontrees(uncoupled::Tuple{I,Vararg{I}}, coupled::I=one(I)) where {I<:Sector}
+function fusiontrees(uncoupled::Tuple{Vararg{I}}, coupled::I) where {I<:Sector}
+    isdual = ntuple(n -> false, length(uncoupled))
+    return fusiontrees(uncoupled, coupled, isdual)
+end
+function fusiontrees(uncoupled::Tuple{I,Vararg{I}}) where {I<:Sector}
+    coupled = one(I)
     isdual = ntuple(n -> false, length(uncoupled))
     return fusiontrees(uncoupled, coupled, isdual)
 end

test/spaces.jl

@@ -290,8 +290,10 @@ println("------------------------------------")
         @test @constinferred(dims(P)) == map(dim, (V1, V2, V3, V4))
         @test @constinferred(dim(P)) == prod(dim, (V1, V2, V3, V4))
         @test @constinferred(dim(P, 2)) == dim(V2)
+        @test @constinferred(dim(one(P))) == 1
         @test first(@constinferred(sectors(P))) ==
               (Trivial(), Trivial(), Trivial(), Trivial())
+        @test first(@constinferred(sectors(one(P)))) == ()
         cube(x) = x^3
         @test @constinferred(cube(V1)) == V1 ⊗ V1 ⊗ V1
         N = 3
@@ -302,6 +304,8 @@ println("------------------------------------")
         @test isempty(blocksectors(P ⊗ ℂ^0))
         @test isempty(@constinferred(sectors(P ⊗ ℂ^0)))
         @test @constinferred(blockdim(P, first(blocksectors(P)))) == dim(P)
+        @test @constinferred(blockdim(P, Trivial())) == dim(P)
+        @test @constinferred(blockdim(one(P), Trivial())) == 1
         @test Base.IteratorEltype(P) == Base.IteratorEltype(typeof(P)) ==
               Base.IteratorEltype(P.spaces)
         @test Base.IteratorSize(P) == Base.IteratorSize(typeof(P)) ==
@@ -340,6 +344,9 @@ println("------------------------------------")
               ProductSpace{ComplexSpace}(())
         @test @constinferred(dims(P)) == map(dim, (V1, V2, V3))
         @test @constinferred(dim(P)) == prod(dim, (V1, V2, V3))
+        @test @constinferred(dim(one(P))) == 1
+        @test first(@constinferred(sectors(one(P)))) == ()
+        @test @constinferred(blockdim(one(P), Irrep[SU₂](0))) == 1
         for s in @constinferred(sectors(P))
             @test hassector(P, s)
             @test @constinferred(dims(P, s)) == dim.((V1, V2, V3), s)