Add unit tests

.github/workflows/test.yml

@@ -0,0 +1,40 @@
+name: Run tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+# needed to allow julia-actions/cache to delete old caches that it has created
+permissions:
+  actions: write
+  contents: read
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        julia-version: ['lts', '1', 'pre']
+        julia-arch: [x64, x86]
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+        exclude:
+          - os: macOS-latest
+            julia-arch: x86
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: ${{ matrix.julia-version }}
+          arch: ${{ matrix.julia-arch }}
+      - uses: julia-actions/cache@v2
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
+        # with:
+        #   annotate: true

Project.toml

@@ -17,3 +17,6 @@ KrylovKit = "0.10.2"
 ProgressMeter = "1.11.0"
 TensorOperations = "5.6.0"
 julia = "1.10"
+
+[workspace]
+projects = ["test"]

README.md

@@ -1,6 +1,8 @@
 # TensorTimeSteps.jl
 
-### A collection of time evolution algorithms for tensor network states
+[![Run tests](https://github.com/BenjaminDecker/TensorTimeSteps.jl/actions/workflows/test.yml/badge.svg)](https://github.com/BenjaminDecker/TensorTimeSteps.jl/actions/workflows/test.yml)
+
+## A collection of time evolution algorithms for tensor network states
 
 Given a Hamiltonian operator $H$ in [MPO](https://tensornetwork.org/mpo/) form, and an initial state $\psi_0$ in [MPS](https://tensornetwork.org/mps/) form, calculate
 
@@ -12,7 +14,7 @@ $$
 
 For now, only the 1-site and 2-site [TDVP](https://tensornetwork.org/mps/algorithms/timeevo/tdvp.html) algorithms are supported, and $H$ and $\psi_0$ must be given as [ITensor](https://docs.itensor.org/ITensorMPS/stable/examples/MPSandMPO.html) MPS/MPO types.
 
-## Usage
+### Usage
 
 Provide some $H$ and $\psi_0$
 ```julia

test/Project.toml

@@ -0,0 +1,6 @@
+[deps]
+ITensorMPS = "0d1a4710-d33b-49a5-8f18-73bdf49b47e2"
+ITensors = "9136182c-28ba-11e9-034c-db9fb085ebd5"
+Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
+TensorTimeSteps = "1f4dac17-e489-46a5-8247-1c82af6382b6"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

test/runtests.jl

@@ -0,0 +1,64 @@
+using TensorTimeSteps, Test, ITensors, ITensorMPS, Random
+
+function create_tfim(N; J=1, g=0.5)
+    sites = siteinds("Qubit", N)
+
+    # tfim Hamiltonian
+    os = OpSum()
+    for j=1:(N-1)
+        os .+= -J, "Z", j, "Z", j+1
+        os .+= -g*J, "X", j
+    end
+    os .+= -g*J, "X", N
+    MPO(os, sites)
+end
+
+function exact_evolution(H, psi_0, T)
+    noprime(
+        contract(
+            exp(-im*T*contract(H)),
+            contract(psi_0)
+        )
+    )
+end
+
+@testset let
+    N = 6
+    T = 1
+    num_steps = 10
+    sweeps_per_time_step = 10
+    maxdim = 32
+    cutoff = 1e-10
+
+    H = create_tfim(N)
+    psi_0 = random_mps(dag(firstsiteinds(H)); linkdims=maxdim)
+    exact=exact_evolution(H, psi_0, T)
+
+    results1 = tdvp1(
+        H,
+        psi_0;
+        step_size=T/num_steps,
+        num_steps=num_steps,
+        sweeps_per_time_step=sweeps_per_time_step,
+        max_bond_dim=maxdim
+    )
+
+    @test isapprox(contract(contract(results1[end]), dag(exact))[1], 1)
+    @test isapprox(contract(contract(results1[1]), dag(contract(psi_0)))[1], 1)
+    @test length(results1) == (num_steps + 1)
+
+    results2 = tdvp2(
+        H,
+        psi_0;
+        step_size=T/num_steps,
+        num_steps=num_steps,
+        sweeps_per_time_step=sweeps_per_time_step,
+        max_bond_dim=maxdim,
+        svd_epsilon=cutoff,
+        switch_when_maxdim_reached=false
+    )
+
+    @test isapprox(contract(contract(results2[end]), dag(exact))[1], 1)
+    @test isapprox(contract(contract(results2[1]), dag(contract(psi_0)))[1], 1)
+    @test length(results2) == (num_steps + 1)
+end