diff --git a/lib/QuanEstimationBase/src/Common/Common.jl b/lib/QuanEstimationBase/src/Common/Common.jl
index f25174b..65d0012 100644
--- a/lib/QuanEstimationBase/src/Common/Common.jl
+++ b/lib/QuanEstimationBase/src/Common/Common.jl
@@ -21,22 +21,10 @@ function repeat_copy(scheme, N)
     [deepcopy(scheme) for _ = 1:N]
 end
 
-function filterZeros!(x::Matrix{T}) where {T<:Complex}
-    x[abs.(x).<eps()] .= zero(T)
-    x
-end
-function filterZeros!(x)
-    filterZeros!.(x)
-end
-
 function filterZeros(x::AbstractVecOrMat{T}) where {T<:Number}
     [x + 1 ≈ 1 ? zero(T) : x for x in x]
 end
 
-function t2Num(t0, dt, t)
-    Int(round((t - t0) / dt)) + 1
-end
-
 function basis(dim, si, ::T)::Array{T} where {T<:Complex}
     result = zeros(T, dim)
     result[si] = 1.0
diff --git a/test/runtests.jl b/test/runtests.jl
index 9812a67..560eabc 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -40,8 +40,8 @@ end
     end
 end
 
-@testset "Parameterization" begin
-    include("test_parameterization.jl")
+@testset "Scheme" begin
+    include("test_scheme.jl")
 end
 
 @testset "Resource" begin
diff --git a/test/test_parameterization.jl b/test/test_scheme.jl
similarity index 87%
rename from test/test_parameterization.jl
rename to test/test_scheme.jl
index e4ff8b1..696132e 100644
--- a/test/test_parameterization.jl
+++ b/test/test_scheme.jl
@@ -80,6 +80,16 @@ function test_kraus()
     evolve(GeneralScheme(; probe=rho0, param=channel))
     evolve(GeneralScheme(; probe=psi, param=channel))
 end
+
+function test_state()
+    @test PlusState() == [1.0, 1.0]/sqrt(2)
+    @test MinusState() == [1.0, -1.0]/sqrt(2)
+    @test BellState() == BellState(1) == [1.0, 0.0, 0.0, 1.0]/sqrt(2)
+    @test BellState(2) == [1.0, 0.0, 0.0, -1.0]/sqrt(2)
+    @test BellState(3) == [0.0, 1.0, 1.0, 0.0]/sqrt(2)
+    @test BellState(4) == [0.0, 1.0, -1.0, 0.0]/sqrt(2)
+end  # function test_state
+
 function test_parameterization()
     test_lindblad(dyn_method=:Ode)
     test_lindblad(dyn_method=:Expm)
@@ -87,4 +97,5 @@ function test_parameterization()
     test_kraus()
 end  # function test_parameterization
 
-test_parameterization()
\ No newline at end of file
+test_parameterization()
+test_state()
\ No newline at end of file