Add tests for is_commutative

src/variable.jl

@@ -47,9 +47,16 @@ Returns whether variables of the given type are commutative, i.e., whether
 `x * y == y * x`.
 """
 function is_commutative end
+function is_commutative(
+    ::Type{P},
+) where {P<:Union{AbstractTerm,AbstractPolynomial}}
+    return is_commutative(monomial_type(P))
+end
 is_commutative(p::_APL) = is_commutative(typeof(p))
 is_commutative(v::AbstractVector) = is_commutative(eltype(v))
+is_commutative(::Type{V}) where {V<:AbstractVector} = is_commutative(eltype(V))
 is_commutative(v::Tuple) = all(is_commutative, v)
+is_commutative(::Type{T}) where {T<:Tuple} = all(is_commutative, fieldtypes(T))
 
 """
     name(v::AbstractVariable)::AbstractString

test/commutative/variable.jl

@@ -2,6 +2,18 @@ import MultivariatePolynomials:
     AbstractVariable, similar_variable, @similar_variable
 
 @testset "Variable" begin
+    @testset "is_commutative" begin
+        function _is_comm_test(p)
+            @test MP.is_commutative(p)
+            @test MP.is_commutative(typeof(p))
+        end
+        Mod.@polyvar x y[1:2]
+        _is_comm_test(x)
+        _is_comm_test(y)
+        _is_comm_test(x^2)
+        _is_comm_test(2x^2)
+        _is_comm_test(sum(y))
+    end
     @testset "polyvar macro index set" begin
         Mod.@polyvar x y z
         Mod.@polyvar x[1:3] y z[1:2]

test/noncommutative/monomial.jl

@@ -92,3 +92,15 @@ end
         @test collect(exponents(X1[i])) == collect(exponents(X2[i])) == Z[i]
     end
 end
+@testset "is_commutative" begin
+    function _is_comm_test(p)
+        @test !MP.is_commutative(p)
+        @test !MP.is_commutative(typeof(p))
+    end
+    Mod.@ncpolyvar x y[1:2]
+    _is_comm_test(x)
+    _is_comm_test(y)
+    _is_comm_test(x^2)
+    _is_comm_test(2x^2)
+    _is_comm_test(sum(y))
+end