Backport: Fix TensorMap constructor for symmetric tensor from dense…

… matrix (#144)

* Fix tensormap constructor from matrix

* Fix tests

src/tensors/tensor.jl

@@ -358,9 +358,10 @@ function TensorMap(data::DenseArray, codom::ProductSpace{S,N₁}, dom::ProductSp
     end
 
     t = TensorMap(undef, eltype(data), codom, dom)
-    project_symmetric!(t, data)
+    data2 = reshape(data, (dims(codom)..., dims(dom)...))
+    project_symmetric!(t, data2)
 
-    if !isapprox(data, convert(Array, t); atol=tol)
+    if !isapprox(data2, convert(Array, t); atol=tol)
         throw(ArgumentError("Data has non-zero elements at incompatible positions"))
     end
 

test/tensors.jl

@@ -112,6 +112,9 @@ for V in spacelist
                     end
                     a = @constinferred convert(Array, t)
                     @test t ≈ @constinferred TensorMap(a, W)
+                    # also test if input is matrix
+                    a2 = reshape(a, prod(dim, codomain(t)), prod(dim, domain(t)))
+                    @test t ≈ @constinferred TensorMap(a2, codomain(t), domain(t))
                 end
             end
         end