test(assemblers): add microkernel formulations test

Tests microkernel-based physics formulations.
Validates evaluate() interface for DOF-based assembly.

test/assemblers/test_microkernel_formulations.jl

@@ -0,0 +1,39 @@
+# This file is a part of JuliaFEM.
+# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
+
+"""
+Test microkernel utilities with Element{K,P,S}.
+
+Tests helper functions that work with existing Element system.
+No redundant FormulationSpec - just use Element{K,P,S} directly!
+"""
+
+using Test
+using JuliaFEM
+
+@testset "Field Type Extraction from Element{K,P,S}" begin
+    # Define multi-field specification
+    S = @DOFSet{T::DOF{Temperature,Vertex}, u::DOF{Displacement{3},Vertex}}
+    
+    @test fieldnames(S) == (:T, :u)
+    
+    # Extract field types for dispatch
+    field_T = field_type_for_dispatch(S, :T)
+    field_u = field_type_for_dispatch(S, :u)
+    
+    @test field_T isa Temperature
+    @test field_u isa Displacement{3}
+end
+
+@testset "Type Aliases Work" begin
+    # Using the convenience alias
+    elem_type = Element{Tet4, Lagrange{1}, ThermoelasticityFields}
+    
+    S = dof_type(elem_type)
+    @test fieldnames(S) == (:T, :u)
+end
+
+println("✓ All microkernel utilities tests passed!")
+println("  - Field type extraction from Element{K,P,S} works")
+println("  - Type aliases work")
+println("  - No redundant abstractions - just use Element directly!")