simplify the imports in core tests

Author: ytdHuang

test/core-test/generalized_master_equation.jl

@@ -1,6 +1,4 @@
-@testitem "Generalized Master Equation" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "Generalized Master Equation" begin
     using LinearAlgebra
 
     N_c = 30

test/core-test/low_rank_dynamics.jl

@@ -1,6 +1,4 @@
-@testitem "Low Rank Dynamics" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "Low Rank Dynamics" begin
     using LinearAlgebra
 
     # Define lattice

test/core-test/quantum_objects.jl

@@ -1,6 +1,4 @@
-@testitem "Quantum Objects" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "Quantum Objects" begin
     using LinearAlgebra
     using SparseArrays
     using StaticArraysCore

test/core-test/quantum_objects_evo.jl

@@ -1,6 +1,4 @@
-@testitem "Quantum Objects Evolution" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "Quantum Objects Evolution" begin
     using LinearAlgebra
     using SparseArrays
     using StaticArraysCore

test/core-test/states_and_operators.jl

@@ -1,6 +1,4 @@
-@testitem "States and Operators" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "States and Operators" begin
     import QuantumToolbox: position, momentum
     using LinearAlgebra
     using SparseArrays

test/core-test/time_evolution.jl

@@ -1,6 +1,4 @@
-@testitem "Time Evolution and Partial Trace" default_imports=false begin
-    using Test
-    using QuantumToolbox
+@testitem "Time Evolution and Partial Trace" begin
     using Random
     using SciMLOperators