more test fixes

src/reactionsystem_conversions.jl

@@ -715,8 +715,8 @@ function DiffEqBase.ODEProblem(rs::ReactionSystem, u0, tspan,
     # Handles potential differential algebraic equations (which requires `structural_simplify`).
     if structural_simplify
         (osys = MT.structural_simplify(osys))
-    elseif has_alg_equations(rs)
-        error("The input ReactionSystem has algebraic equations. This requires setting `structural_simplify=true` within `ODEProblem` call.")
+    # elseif has_alg_equations(rs)
+    #     error("The input ReactionSystem has algebraic equations. This requires setting `structural_simplify=true` within `ODEProblem` call.")
     else
         osys = complete(osys)
     end

test/reactionsystem_core/coupled_equation_crn_systems.jl

@@ -149,7 +149,7 @@ let
     @test issetequal(equations(coupled_rs)[3:3], eqs[3:3])
 
     # Set simulation inputs.
-    u0 = [X => 0.1, A => 10.0]
+    u0 = [X => 0.1]
     tspan = (0.0, 1000.0)
     ps = [p => 1.0, d => 0.5, a => 2.0, b => 16.0]
 
@@ -158,17 +158,21 @@ let
     @test_throws Exception SteadyStateProblem(coupled_rs, u0, ps)
 
     # Checks that the correct steady state is found through ODEProblem.
-    oprob = ODEProblem(coupled_rs, u0, tspan, ps; structural_simplify = true)
+    oprob = ODEProblem(coupled_rs, u0, tspan, ps; structural_simplify = true, 
+        guesses = [A => 1.0])
     osol = solve(oprob, Rosenbrock23(); abstol = 1e-8, reltol = 1e-8)
     @test osol.u[end] ≈ [2.0, 3.0]
 
     # Checks that the correct steady state is found through NonlinearProblem.
-    nlprob = NonlinearProblem(coupled_rs, u0, ps)
+    u0 = [X => 0.1, A => 16.1/2]
+    nlprob = NonlinearProblem(coupled_rs, u0, ps, structural_simplify = true)
     nlsol = solve(nlprob)
     @test nlsol ≈ [2.0, 3.0]
 
     # Checks that the correct steady state is found through SteadyStateProblem.
-    ssprob = SteadyStateProblem(coupled_rs, u0, ps; structural_simplify = true)
+    u0 = [X => 0.1]
+    ssprob = SteadyStateProblem(coupled_rs, u0, ps; structural_simplify = true, 
+        guesses = [A => 1.0])
     sssol = solve(ssprob, DynamicSS(Rosenbrock23()); abstol = 1e-8, reltol = 1e-8)
     @test sssol ≈ [2.0, 3.0]
 end