test: add regression test

.Lib9c.Tests/Action/DPoS/Sys/UpdateValidatorsTest.cs

@@ -0,0 +1,92 @@
+namespace Lib9c.Tests.Action.DPoS.Sys
+{
+    using System.Linq;
+    using Libplanet.Action.State;
+    using Libplanet.Crypto;
+    using Libplanet.Types.Assets;
+    using Nekoyume.Action.DPoS;
+    using Nekoyume.Action.DPoS.Control;
+    using Nekoyume.Action.DPoS.Misc;
+    using Nekoyume.Action.DPoS.Model;
+    using Nekoyume.Action.DPoS.Sys;
+    using Nekoyume.Module;
+    using Xunit;
+
+    public class UpdateValidatorsTest : PoSTest
+    {
+        [Fact]
+        public void Execute()
+        {
+            // Prepare initial state.
+            IWorld initialState = new World(new MockWorldState());
+            const int count = 4;
+            var validatorKeys = Enumerable.Range(0, count).Select(_ => new PrivateKey().PublicKey).ToArray();
+            initialState = validatorKeys.Aggregate(
+                initialState,
+                (current, key) => current.MintAsset(
+                    new ActionContext(),
+                    key.Address,
+                    new FungibleAssetValue(Asset.GovernanceToken, 1, 0)));
+            foreach (var key in validatorKeys)
+            {
+                Assert.Equal(1, initialState.GetBalance(key.Address, Asset.GovernanceToken).MajorUnit);
+                Assert.Equal(0, initialState.GetBalance(key.Address, Asset.GovernanceToken).MinorUnit);
+            }
+
+            // Stake 1 for each validator.
+            foreach (var key in validatorKeys)
+            {
+                initialState = new PromoteValidator(
+                    key,
+                    new FungibleAssetValue(Asset.GovernanceToken, 1, 0)).Execute(
+                        new ActionContext
+                        {
+                            PreviousState = initialState,
+                            Signer = key.Address,
+                        });
+            }
+
+            Assert.Equal(0, ValidatorSetCtrl.FetchBondedValidatorSet(initialState).Item2.Count);
+            Assert.Equal(0, initialState.GetValidatorSet().TotalCount);
+
+            // Execute the action.
+            initialState = new UpdateValidators().Execute(
+                new ActionContext
+                {
+                    PreviousState = initialState,
+                    LastCommit = null,
+                });
+
+            Assert.Equal(count, ValidatorSetCtrl.FetchBondedValidatorSet(initialState).Item2.Count);
+            Assert.Equal(count, initialState.GetValidatorSet().TotalCount);
+            Assert.Equal(
+                validatorKeys.ToHashSet(),
+                initialState.GetValidatorSet()
+                    .Validators.Select(validator => validator.PublicKey)
+                    .ToHashSet());
+
+            initialState = new Undelegate(
+                Validator.DeriveAddress(validatorKeys[0].Address),
+                new FungibleAssetValue(Asset.Share, 1, 0)).Execute(
+                    new ActionContext
+                    {
+                        PreviousState = initialState,
+                        Signer = validatorKeys[0].Address,
+                    });
+
+            Assert.Equal(count, ValidatorSetCtrl.FetchBondedValidatorSet(initialState).Item2.Count);
+            Assert.Equal(count, initialState.GetValidatorSet().TotalCount);
+
+            // Execute the action.
+            initialState = new UpdateValidators().Execute(
+                new ActionContext
+                {
+                    PreviousState = initialState,
+                    LastCommit = null,
+                });
+
+            Assert.Equal(count - 1, ValidatorSetCtrl.FetchBondedValidatorSet(initialState).Item2.Count);
+            Assert.Equal(count - 1, initialState.GetValidatorSet().TotalCount);
+        }
+    }
+}