diff --git a/x/slashing/simulation/operation_test.go b/x/slashing/simulation/operation_test.go
new file mode 100644
index 0000000000..0987daadb2
--- /dev/null
+++ b/x/slashing/simulation/operation_test.go
@@ -0,0 +1,149 @@
+package simulation_test
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	abci "github.com/tendermint/tendermint/abci/types"
+
+	"github.com/cosmos/cosmos-sdk/simapp"
+	simappparams "github.com/cosmos/cosmos-sdk/simapp/params"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	simtypes "github.com/cosmos/cosmos-sdk/types/simulation"
+	distrtypes "github.com/cosmos/cosmos-sdk/x/distribution/types"
+	minttypes "github.com/cosmos/cosmos-sdk/x/mint/types"
+	"github.com/cosmos/cosmos-sdk/x/slashing/simulation"
+	"github.com/cosmos/cosmos-sdk/x/slashing/types"
+	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
+)
+
+// TestWeightedOperations tests the weights of the operations.
+func TestWeightedOperations(t *testing.T) {
+	app, ctx := createTestApp(false)
+	ctx.WithChainID("test-chain")
+
+	cdc := app.Codec()
+	appParams := make(simtypes.AppParams)
+
+	s := rand.NewSource(1)
+	r := rand.New(s)
+	accs := simtypes.RandomAccounts(r, 3)
+
+	expected := []struct {
+		weight     int
+		opMsgRoute string
+		opMsgName  string
+	}{{simappparams.DefaultWeightMsgUnjail, types.ModuleName, types.TypeMsgUnjail}}
+
+	weightesOps := simulation.WeightedOperations(appParams, cdc, app.AccountKeeper, app.BankKeeper, app.SlashingKeeper, app.StakingKeeper)
+	for i, w := range weightesOps {
+		operationMsg, _, _ := w.Op()(r, app.BaseApp, ctx, accs, ctx.ChainID())
+		// the following checks are very much dependent from the ordering of the output given
+		// by WeightedOperations. if the ordering in WeightedOperations changes some tests
+		// will fail
+		require.Equal(t, expected[i].weight, w.Weight(), "weight should be the same")
+		require.Equal(t, expected[i].opMsgRoute, operationMsg.Route, "route should be the same")
+		require.Equal(t, expected[i].opMsgName, operationMsg.Name, "operation Msg name should be the same")
+	}
+}
+
+// TestSimulateMsgUnjail tests the normal scenario of a valid message of type types.MsgUnjail.
+// Abonormal scenarios, where the message is created by an errors, are not tested here.
+func TestSimulateMsgUnjail(t *testing.T) {
+	app, ctx := createTestApp(false)
+	blockTime := time.Now().UTC()
+	ctx = ctx.WithBlockTime(blockTime)
+
+	// setup 3 accounts
+	s := rand.NewSource(1)
+	r := rand.New(s)
+	accounts := getTestingAccounts(t, r, app, ctx, 3)
+
+	// setup accounts[0] as validator0
+	validator0 := getTestingValidator0(t, app, ctx, accounts)
+
+	// setup validator0 by consensus address
+	app.StakingKeeper.SetValidatorByConsAddr(ctx, validator0)
+	val0ConsAddress := sdk.ConsAddress(validator0.GetConsPubKey().Address())
+	info := types.NewValidatorSigningInfo(val0ConsAddress, int64(4), int64(3),
+		time.Unix(2, 0), false, int64(10))
+	app.SlashingKeeper.SetValidatorSigningInfo(ctx, val0ConsAddress, info)
+
+	// put validator0 in jail
+	app.StakingKeeper.Jail(ctx, val0ConsAddress)
+
+	// setup self delegation
+	delTokens := sdk.TokensFromConsensusPower(2)
+	validator0, issuedShares := validator0.AddTokensFromDel(delTokens)
+	val0AccAddress := sdk.AccAddress(validator0.OperatorAddress.Bytes())
+	selfDelegation := stakingtypes.NewDelegation(val0AccAddress, validator0.OperatorAddress, issuedShares)
+	app.StakingKeeper.SetDelegation(ctx, selfDelegation)
+	app.DistrKeeper.SetDelegatorStartingInfo(ctx, validator0.OperatorAddress, val0AccAddress, distrtypes.NewDelegatorStartingInfo(2, sdk.OneDec(), 200))
+
+	// begin a new block
+	app.BeginBlock(abci.RequestBeginBlock{Header: abci.Header{Height: app.LastBlockHeight() + 1, AppHash: app.LastCommitID().Hash, Time: blockTime}})
+
+	// execute operation
+	op := simulation.SimulateMsgUnjail(app.AccountKeeper, app.BankKeeper, app.SlashingKeeper, app.StakingKeeper)
+	operationMsg, futureOperations, err := op(r, app.BaseApp, ctx, accounts, "")
+	require.NoError(t, err)
+
+	var msg types.MsgUnjail
+	types.ModuleCdc.UnmarshalJSON(operationMsg.Msg, &msg)
+
+	require.True(t, operationMsg.OK)
+	require.Equal(t, types.TypeMsgUnjail, msg.Type())
+	require.Equal(t, "cosmosvaloper1tnh2q55v8wyygtt9srz5safamzdengsn9dsd7z", msg.GetValidatorAddr().String())
+	require.Len(t, futureOperations, 0)
+}
+
+// returns context and an app with updated mint keeper
+func createTestApp(isCheckTx bool) (*simapp.SimApp, sdk.Context) {
+	app := simapp.Setup(isCheckTx)
+
+	ctx := app.BaseApp.NewContext(isCheckTx, abci.Header{})
+	app.MintKeeper.SetParams(ctx, minttypes.DefaultParams())
+	app.MintKeeper.SetMinter(ctx, minttypes.DefaultInitialMinter())
+
+	return app, ctx
+}
+
+func getTestingAccounts(t *testing.T, r *rand.Rand, app *simapp.SimApp, ctx sdk.Context, n int) []simtypes.Account {
+	accounts := simtypes.RandomAccounts(r, n)
+
+	initAmt := sdk.TokensFromConsensusPower(200)
+	initCoins := sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, initAmt))
+
+	// add coins to the accounts
+	for _, account := range accounts {
+		acc := app.AccountKeeper.NewAccountWithAddress(ctx, account.Address)
+		app.AccountKeeper.SetAccount(ctx, acc)
+		err := app.BankKeeper.SetBalances(ctx, account.Address, initCoins)
+		require.NoError(t, err)
+	}
+
+	return accounts
+}
+
+func getTestingValidator0(t *testing.T, app *simapp.SimApp, ctx sdk.Context, accounts []simtypes.Account) stakingtypes.Validator {
+	commission0 := stakingtypes.NewCommission(sdk.ZeroDec(), sdk.OneDec(), sdk.OneDec())
+	return getTestingValidator(t, app, ctx, accounts, commission0, 0)
+}
+
+func getTestingValidator(t *testing.T, app *simapp.SimApp, ctx sdk.Context, accounts []simtypes.Account, commission stakingtypes.Commission, n int) stakingtypes.Validator {
+	account := accounts[n]
+	valPubKey := account.PubKey
+	valAddr := sdk.ValAddress(account.PubKey.Address().Bytes())
+	validator := stakingtypes.NewValidator(valAddr, valPubKey, stakingtypes.Description{})
+	validator, err := validator.SetInitialCommission(commission)
+	require.NoError(t, err)
+
+	validator.DelegatorShares = sdk.NewDec(100)
+	validator.Tokens = sdk.NewInt(1000000)
+
+	app.StakingKeeper.SetValidator(ctx, validator)
+
+	return validator
+}