check coloring of all component spaces + fix tests

Author: borisdevos

src/vectorspaces/sumspace.jl

@@ -171,8 +171,27 @@ end
 TensorKit.unitspace(S::Type{<:SumSpace}) = SumSpace(TensorKit.unitspace(eltype(S)))
 TensorKit.zerospace(::Type{SumSpace{S}}) where {S} = SumSpace{S}()
 
-TensorKit.leftunitspace(S::SumSpace{<:GradedSpace}) = SumSpace(leftunitspace(first(S)))
-TensorKit.rightunitspace(S::SumSpace{<:GradedSpace}) = SumSpace(rightunitspace(first(S)))
+function TensorKit.leftunitspace(S::SumSpace{<:GradedSpace})
+    I = sectortype(S)
+    if UnitStyle(I) isa GenericUnit
+        !isempty(sectors(S)) || throw(ArgumentError("Cannot determine the left unit of an empty SumSpace"))
+        TensorKit._allequal(leftunit, sectors(S)) ||
+            throw(ArgumentError("sectors of $S do not have the same left unit"))
+    end
+
+    return SumSpace(leftunitspace(first(S)))
+end
+
+function TensorKit.rightunitspace(S::SumSpace{<:GradedSpace})
+    I = sectortype(S)
+    if UnitStyle(I) isa GenericUnit
+        !isempty(sectors(S)) || throw(ArgumentError("Cannot determine the right unit of an empty SumSpace"))
+        TensorKit._allequal(rightunit, sectors(S)) ||
+            throw(ArgumentError("sectors of $S do not have the same right unit"))
+    end
+
+    return SumSpace(rightunitspace(first(S)))
+end
 TensorKit.isunitspace(S::SumSpace{<:GradedSpace}) = all(isunitspace, S.spaces)
 
 # Promotion and conversion

test/vectorspaces/sumspace.jl

@@ -209,8 +209,10 @@ end
         @test unitspace(typeof(W)) == ⊞(Vect[IsingBimodule]((1, 1, 0) => 1, (2, 2, 0) => 1))
     end
 
-    @test leftunitspace(V) == ⊞(WC, WD, WC)
-    @test rightunitspace(V) == ⊞(WC, WD, WD)
+    @test_throws ArgumentError leftunitspace(V)
+    @test_throws ArgumentError rightunitspace(V)
+    @test leftunitspace(SumSpace(V1, V3)) == WC
+    @test rightunitspace(SumSpace(V2, V3)) == WD
     @test leftunitspace(WMop) == WD && rightunitspace(WMop) == WC
     @test leftunitspace(WM) == WC && rightunitspace(WM) == WD
     @test unitspace(WM) == unitspace(WMop) == ⊞(Vect[IsingBimodule]((1, 1, 0) => 1, (2, 2, 0) => 1))