Add tests

Author: YingboMa

test/linalg.jl

@@ -0,0 +1,17 @@
+using ModelingToolkit
+using Test
+
+A = [
+     0  1   1   2   2  1  1   2  1   2
+     0  1  -1  -3  -2  2  1  -5  0  -5
+     0  1   2   2   1  1  2   1  1   2
+     0  1   1   1   2  1  1   2  2   1
+     0  2   1   2   2  2  2   1  1   1
+     0  1   1   1   2  2  1   1  2   1
+     0  2   1   2   2  1  2   1  1   2
+     0  1   7  17  14  2  1  19  4  23
+     0  1  -1  -3  -2  1  1  -4  0  -5
+     0  1   1   2   2  1  1   2  2   2
+    ]
+N = ModelingToolkit.nullspace(A)
+@test iszero(A * N)

test/runtests.jl

@@ -1,5 +1,6 @@
 using SafeTestsets, Test
 
+@safetestset "Linear Algebra Test" begin include("linalg.jl") end
 @safetestset "AbstractSystem Test" begin include("abstractsystem.jl") end
 @safetestset "Variable scope tests" begin include("variable_scope.jl") end
 @safetestset "Symbolic parameters test" begin include("symbolic_parameters.jl") end