Add tests

src/MultivariateBases.jl

@@ -23,7 +23,8 @@ function MP.polynomial_type(::Type{<:Algebra{B}}, ::Type{T}) where {B,T}
     return MP.polynomial_type(B, T)
 end
 SA.basis(a::Algebra) = a.basis
-MA.promote_operation(::typeof(SA.basis), ::Type{<:Algebra{B}}) where {B} = B
+# Is this needed ?
+#MA.promote_operation(::typeof(SA.basis), ::Type{<:Algebra{B}}) where {B} = B
 
 #Base.:(==)(::Algebra{BT1,B1,M}, ::Algebra{BT2,B2,M}) where {BT1,B1,BT2,B2,M} = true
 #Base.:(==)(::Algebra, ::Algebra) = false
@@ -64,13 +65,14 @@ function algebra(
     return Algebra{typeof(basis),B,M}(basis)
 end
 
-function MA.promote_operation(
-    ::typeof(algebra),
-    BT::Type{
-        <:Union{QuotientBasis{Polynomial{B,M}},FullBasis{B,M},SubBasis{B,M}},
-    },
-) where {B,M}
-    return Algebra{BT,B,M}
-end
+# Needed ?
+#function MA.promote_operation(
+#    ::typeof(algebra),
+#    BT::Type{
+#        <:Union{QuotientBasis{Polynomial{B,M}},FullBasis{B,M},SubBasis{B,M}},
+#    },
+#) where {B,M}
+#    return Algebra{BT,B,M}
+#end
 
 end # module

test/runtests.jl

@@ -9,6 +9,7 @@ function api_test(B::Type{<:MB.AbstractMonomialIndexed}, degree)
     @polyvar x[1:2]
     M = typeof(prod(x))
     full_basis = FullBasis{B,M}()
+    @test sprint(show, MB.algebra(full_basis)) == "Polynomial algebra of $B basis"
     for basis in [
         maxdegree_basis(full_basis, x, degree),
         explicit_basis_covering(
@@ -34,6 +35,11 @@ function api_test(B::Type{<:MB.AbstractMonomialIndexed}, degree)
         @test polynomial_type(basis, Float64) == polynomial_type(x[1], Float64)
         #@test polynomial(i -> 0.0, basis) isa polynomial_type(basis, Float64)
     end
+    p = MB.Polynomial{B}(x[1]^2)
+    @test polynomial_type(x[1]^2, String) == polynomial_type(typeof(p), String)
+    a = MB.algebra_element(p)
+    @test typeof(polynomial(a)) == polynomial_type(typeof(a))
+    @test typeof(polynomial(a)) == polynomial_type(typeof(p), Int)
 end
 
 function univ_orthogonal_test(