# Token - Let Players Set a Wager

Make sure you have everything you need before proceeding:

synopsis

In this section, you will:

  • Add wagers.
  • Work with the Bank module.
  • Handle money.
  • Do integration tests.

With the introduction of game expiry in the previous section and other features, you have now addressed the cases when two players start a game and finish it, or let it expire.

In this section you will add an extra layer to a game, with wagers or stakes. Your application already includes all the necessary modules. This section relies on the bank module in particular.

Players choose to wager money or not, and the winner gets both wagers. The forfeiter loses their wager. To reduce complexity, start by letting players wager in the staking token of your application.

# New information

Add this wager value to the StoredGame's Protobuf definition:

Copy message StoredGame { ... uint64 wager = 12; } proto checkers stored_game.proto View source

You can let players choose the wager they want by adding a dedicated field in the message to create a game, in proto/checkers/tx.proto:

Copy message MsgCreateGame { ... uint64 wager = 4; } proto checkers tx.proto View source

Have Ignite CLI and Protobuf recompile these two files:

Copy $ ignite generate proto-go

Now add a helper function to StoredGame using the Cosmos SDK Coin in full_game.go:

Copy func (storedGame *StoredGame) GetWagerCoin() (wager sdk.Coin) { return sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(int64(storedGame.Wager))) } x checkers types full_game.go View source

This encapsulates information about the wager (where sdk.DefaultBondDenom is most likely "stake").

# Saving the wager

Time to make sure that the new field is saved in the storage and it is part of the creation event.

  1. Define a new event key as a constant:

    Copy const ( StoredGameEventWager = "Wager" ) x checkers types keys.go View source
  2. Set the actual value in the new StoredGame as it is instantiated in the create game handler:

    Copy storedGame := types.StoredGame{ ... Wager: msg.Wager, } x checkers keeper msg_server_create_game.go View source
  3. And in the event:

    Copy ctx.EventManager().EmitEvent( sdk.NewEvent(sdk.EventTypeMessage, ... sdk.NewAttribute(types.StoredGameEventWager, strconv.FormatUint(msg.Wager, 10)), ) ) x checkers keeper msg_server_create_game.go View source
  4. Modify the constructor among the interface definition of MsgCreateGame in x/checkers/types/message_create_game.go to avoid surprises:

    Copy func NewMsgCreateGame(creator string, red string, black string, wager uint64) *MsgCreateGame { return &MsgCreateGame{ ... Wager: wager, } } x checkers types message_create_game.go View source

# Declaring expectations

On its own the Wager field does not make players pay the wager or receive rewards. You need to add handling actions which ask the bank module to perform the required token transfers. For that, your keeper needs to ask for a bank instance during setup.

The only way to have access to a capability with the object-capability model of the Cosmos SDK is to be given the reference to an instance which already has this capability.

Payment handling is implemented by having your keeper hold wagers in escrow while the game is being played. The bank module has functions to transfer tokens from any account to your module and vice-versa.

Alternatively, your keeper could burn tokens when playing and mint them again when paying out. However, this makes your blockchain's total supply falsely fluctuate. Additionally, this burning and minting may prove questionable when you later introduce IBC tokens.

Declare an interface that narrowly declares the functions from other modules that you expect for your module. The conventional file for these declarations is x/checkers/types/expected_keepers.go.

The bank module has many capabilities, but all you need here are two functions. Therefore, you redeclare the functions like so:

Copy type BankKeeper interface { SendCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error } x checkers types expected_keepers.go View source

These two functions must exactly match the functions declared in the bank's keeper.go file (opens new window). Copy the declarations directly from the bank's file. In Go, any object with these two functions is a BankKeeper.

# Obtaining the capability

With your requirements declared, it is time to make sure your keeper receives a reference to a bank keeper. First add a BankKeeper to your keeper in x/checkers/keeper/keeper.go:

Copy type ( Keeper struct { bank types.BankKeeper ... } ) x checkers keeper keeper.go View source

This BankKeeper is your newly declared narrow interface. Do not forget to adjust the constructor accordingly:

Copy func NewKeeper( bank types.BankKeeper, ... ) *Keeper { return &Keeper{ bank: bank, ... } } x checkers keeper keeper.go View source

Next, update where the constructor is called and pass a proper instance of bank keeper. This happens in app/app.go:

Copy app.CheckersKeeper = *checkersmodulekeeper.NewKeeper( app.BankKeeper, ... ) app app.go View source

This app.BankKeeper is a full bank keeper that also conforms to your BankKeeper interface.

Finally, inform the app that your checkers module is going to hold balances in escrow by adding it to the list of permitted modules:

Copy maccPerms = map[string][]string{ ... checkersmoduletypes.ModuleName: nil, } app app.go View source

It is only keeping funds in escrow and not minting or burning, hence the nil.

One last step. Before your module can keep money in escrow, it needs to be whitelisted by the bank module. You do this in the maccperms:

Copy maccPerms = map[string][]string{ ... checkersmoduletypes.ModuleName: nil, } app app.go View source

If you compare it to the other maccperms lines, the new line does not mention any authtypes.Minter or authtypes.Burner. Indeed nil is what you need to keep in escrow. For your information, the bank creates an address for your module's escrow account. When you have the full app, you can access it with:

Copy import( "github.com/alice/checkers/x/checkers/types" ) checkersModuleAddress := app.AccountKeeper.GetModuleAddress(types.ModuleName)

One last step. Before your module can keep money in escrow, it needs to be whitelisted by the bank module. You do this in the maccperms:

Copy maccPerms = map[string][]string{ ... checkersmoduletypes.ModuleName: nil, } app app.go View source

If you compare it to the other maccperms lines, the new line does not mention any authtypes.Minter or authtypes.Burner. Indeed nil is what you need to keep in escrow. For your information, the bank creates an address for your module's escrow account. When you have the full app, you can access it with:

Copy import( "github.com/alice/checkers/x/checkers/types" ) checkersModuleAddress := app.AccountKeeper.GetModuleAddress(types.ModuleName)

# Preparing expected errors

There are several new error situations that you can enumerate with new variables:

Copy ErrRedCannotPay = sdkerrors.Register(ModuleName, 1112, "red cannot pay the wager") ErrBlackCannotPay = sdkerrors.Register(ModuleName, 1113, "black cannot pay the wager") ErrNothingToPay = sdkerrors.Register(ModuleName, 1115, "there is nothing to pay, should not have been called") ErrCannotRefundWager = sdkerrors.Register(ModuleName, 1116, "cannot refund wager to: %s") ErrCannotPayWinnings = sdkerrors.Register(ModuleName, 1117, "cannot pay winnings to winner") ErrNotInRefundState = sdkerrors.Register(ModuleName, 1118, "game is not in a state to refund, move count: %d") x checkers types errors.go View source

# Money handling steps

With the bank now in your keeper, it is time to have your keeper handle the money. Keep this concern in its file, as the function are reused on a play, reject, and forfeit.

Create the new file x/checkers/keeper/wager_handler.go and add three functions to collect a wager, refund a wager, and pay winnings:

Copy func (k *Keeper) CollectWager(ctx sdk.Context, storedGame *types.StoredGame) error func (k *Keeper) MustPayWinnings(ctx sdk.Context, storedGame *types.StoredGame) func (k *Keeper) MustRefundWager(ctx sdk.Context, storedGame *types.StoredGame) x checkers keeper wager_handler.go View source

The Must prefix in the function means that the transaction either takes place or a panic is issued. If a player cannot pay the wager, it is a user-side error and the user must be informed of a failed transaction. If the module cannot pay, it means the escrow account has failed. This error is much more serious: an invariant has been violated and the whole application must be terminated.

Now set up collecting a wager, paying winnings, and refunding a wager:

  1. Collecting wagers happens on a player's first move. Therefore, differentiate between players:

    Copy if storedGame.MoveCount == 0 { // Black plays first } else if storedGame.MoveCount == 1 { // Red plays second } return nil x checkers keeper wager_handler.go View source

    Get the address for the black player:

    Copy black, err := storedGame.GetBlackAddress() if err != nil { panic(err.Error()) } x checkers keeper wager_handler.go View source

    Try to transfer into the escrow:

    Copy err = k.bank.SendCoinsFromAccountToModule(ctx, black, types.ModuleName, sdk.NewCoins(storedGame.GetWagerCoin())) if err != nil { return sdkerrors.Wrapf(err, types.ErrBlackCannotPay.Error()) } x checkers keeper wager_handler.go View source

    Then do the same for the red player.

  2. Paying winnings takes place when the game has a declared winner. First get the winner. "No winner" is not an acceptable situation in this MustPayWinnings. The caller of the function must ensure there is a winner:

    Copy winnerAddress, found, err := storedGame.GetWinnerAddress() if err != nil { panic(err.Error()) } if !found { panic(fmt.Sprintf(types.ErrCannotFindWinnerByColor.Error(), storedGame.Winner)) } x checkers keeper wager_handler.go View source

    Then get the winnings to pay:

    Copy winnings := storedGame.GetWagerCoin() if storedGame.MoveCount == 0 { panic(types.ErrNothingToPay.Error()) } else if 1 < storedGame.MoveCount { winnings = winnings.Add(winnings) } x checkers keeper wager_handler.go View source

    You double the wager only if the red player has also played and therefore both players have paid their wagers. Then pay the winner:

    Copy err = k.bank.SendCoinsFromModuleToAccount(ctx, types.ModuleName, winnerAddress, sdk.NewCoins(winnings)) if err != nil { panic(types.ErrCannotPayWinnings.Error()) } x checkers keeper wager_handler.go View source
  3. Finally, refunding wagers takes place when the game has partially started, i.e. only one party has paid, or when the game ends in a draw. In this narrow case of MustRefundWager:

    Copy if storedGame.MoveCount == 1 { // Refund } else if storedGame.MoveCount == 0 { // Do nothing } else { // TODO Implement a draw mechanism. panic(fmt.Sprintf(types.ErrNotInRefundState.Error(), storedGame.MoveCount)) } x checkers keeper wager_handler.go View source

    Refund the black player when there has been a single move:

    Copy black, err := storedGame.GetBlackAddress() if err != nil { panic(err.Error()) } err = k.bank.SendCoinsFromModuleToAccount(ctx, types.ModuleName, black, sdk.NewCoins(storedGame.GetWagerCoin())) if err != nil { panic(fmt.Sprintf(types.ErrCannotRefundWager.Error(), rules.BLACK_PLAYER.Color)) } x checkers keeper wager_handler.go View source

    If the module cannot pay, then there is a panic as the escrow has failed.

You will notice that no special case is made when the wager is zero. This is a design choice here, and which way you choose to go is up to you. Not contacting the bank unnecessarily is cheaper in gas. On the other hand, why not outsource the zero check to the bank?

You will notice that no special case is made when the wager is zero. This is a design choice here, and which way you choose to go is up to you. Not contacting the bank unnecessarily is cheaper in gas. On the other hand, why not outsource the zero check to the bank?

# Insert wager handling

With the desired steps defined in the wager handling functions, it is time to invoke them at the right places in the message handlers.

  1. When a player plays for the first time:

    Copy err = k.Keeper.CollectWager(ctx, &storedGame) if err != nil { return nil, err } x checkers keeper msg_server_play_move.go View source
  2. When a player wins as a result of a move:

    Copy if storedGame.Winner == rules.NO_PLAYER.Color { ... } else { ... k.Keeper.MustPayWinnings(ctx, &storedGame) } x checkers keeper msg_server_play_move.go View source
  3. When a player rejects a game:

    Copy k.Keeper.MustRefundWager(ctx, &storedGame) x checkers keeper msg_server_reject_game.go View source
  4. When a game expires and there is a forfeit, make sure to only refund or pay full winnings when applicable. The logic needs to be adjusted:

    Copy if deadline.Before(ctx.BlockTime()) { ... if storedGame.MoveCount <= 1 { ... if storedGame.MoveCount == 1 { k.MustRefundWager(ctx, &storedGame) } } else { ... k.MustPayWinnings(ctx, &storedGame) ... } } x checkers keeper end_block_server_game.go View source

# Unit Integration tests

If you try running your existing tests you will see a lot of null pointer exceptions. That's because currently the tests set up your checkers keeper without a bank keeper (opens new window). Cosmos SDK does not have mocks (opens new window), so instead of passing a mocked bank when setting up your test keeper you need to build a proper bank keeper too. Fortunately, you do not have to do this from scratch: taking inspiration from tests on the bank module (opens new window), prepare your code and tests in order to accommodate and create a full app which will contain a bank keeper.

Your existing tests, although never pure unit tests, will become true integration tests.

Previously, each test function took a t *testing.T (opens new window) object. Now, each test function will be a method on a test suite that inherits from testify's suite (opens new window). This has the advantage that your test suite can have as many fields as is necessary or useful. The objects that you have used and would welcome in the suite are:

Copy keeper keeper.Keeper msgServer types.MsgServer ctx sdk.Context

You can spread the suite's methods to different files, so as to keep consistent naming for your test files.

When testing, go test will find the suite because you add a regular test (opens new window) that initializes the suite and runs it. The test suite is then automatically initialized with its SetupTest (opens new window) function via its parent suite class. After that, all the methods of the test suite are run.

# Accommodate your code

  1. To get the compilation error out of the way, for basic tests that do not require integration you can add an empty bank keeper on func setupKeeper(t testing.TB):

    Copy keeper := keeper.NewKeeper( *new(bankkeeper.Keeper), ... } x checkers keeper keeper_test.go View source

    Keep this setupKeeper function because tests created by Ignite CLI expect it.

  2. Ignite CLI created a default constructor for your App with a cosmoscmd.App (opens new window) return type, but this is not convenient. Instead of risking breaking other dependencies, add a new constructor with your App (opens new window) as the return type.

  3. Add other elements taken from Cosmos SDK tests, like encoding.go (opens new window), proto.go (opens new window), and test_helpers.go (opens new window), in which you must also initialize your checkers genesis:

    Copy checkersGenesis := types.DefaultGenesis() genesisState[types.ModuleName] = app.AppCodec().MustMarshalJSON(checkersGenesis) app test_helpers.go View source
  4. Define your test suite in a new keeper_integration_test.go file:

    Copy type IntegrationTestSuite struct { suite.Suite app *checkersapp.App msgServer types.MsgServer ctx sdk.Context queryClient types.QueryClient } x checkers keeper keeper_integration_test.go View source
  5. Direct go test to it:

    Copy func TestCheckersKeeperTestSuite(t *testing.T) { suite.Run(t, new(IntegrationTestSuite)) } x checkers keeper keeper_integration_test.go View source
  6. Create the suite.SetupTest function, taking inspiration from the bank tests (opens new window):

    Copy func (suite *IntegrationTestSuite) SetupTest() { app := checkersapp.Setup(false) ctx := app.BaseApp.NewContext(false, tmproto.Header{}) app.AccountKeeper.SetParams(ctx, authtypes.DefaultParams()) app.BankKeeper.SetParams(ctx, banktypes.DefaultParams()) checkersModuleAddress = app.AccountKeeper.GetModuleAddress(types.ModuleName).String() queryHelper := baseapp.NewQueryServerTestHelper(ctx, app.InterfaceRegistry()) types.RegisterQueryServer(queryHelper, app.CheckersKeeper) queryClient := types.NewQueryClient(queryHelper) suite.app = app suite.msgServer = keeper.NewMsgServerImpl(app.CheckersKeeper) suite.ctx = ctx suite.queryClient = queryClient } x checkers keeper keeper_integration_test.go View source

    This SetupTest function (opens new window) is like a beforeEach as it is named in other test libraries. With it, you always get a new app with each test, without interference between them. Do not omit it (opens new window) unless you have specific reasons to do so.

    Also note that it collects your checkersModuleAddress for later use in tests that check events and balances:

    Copy var ( checkersModuleAddress string ) x checkers keeper keeper_integration_test.go View source

# Helpers for money checking

Your new tests will include checks on wagers being paid, lost, and won, so your tests need to initialize some bank balances for your players. This is made easier with a few helpers, including a helper to confirm a bank balance.

  1. Make a bank genesis Balance (opens new window) type from primitives:

    Copy func makeBalance(address string, balance int64) banktypes.Balance { return banktypes.Balance{ Address: address, Coins: sdk.Coins{ sdk.Coin{ Denom: sdk.DefaultBondDenom, Amount: sdk.NewInt(balance), }, }, } } x checkers keeper keeper_integration_test.go View source
  2. Declare default balances that will be useful for you:

    Copy const ( alice = "cosmos1jmjfq0tplp9tmx4v9uemw72y4d2wa5nr3xn9d3" bob = "cosmos1xyxs3skf3f4jfqeuv89yyaqvjc6lffavxqhc8g" carol = "cosmos1e0w5t53nrq7p66fye6c8p0ynyhf6y24l4yuxd7" balAlice = 50000000 balBob = 20000000 balCarol = 10000000 ) x checkers keeper keeper_integration_test.go View source
  3. Make your preferred bank genesis state:

    Copy func getBankGenesis() *banktypes.GenesisState { coins := []banktypes.Balance{ makeBalance(alice, balAlice), makeBalance(bob, balBob), makeBalance(carol, balCarol), } supply := banktypes.NewSupply(coins[0].Coins.Add(coins[1].Coins...).Add(coins[2].Coins...)) state := banktypes.NewGenesisState( banktypes.DefaultParams(), coins, supply.GetTotal(), []banktypes.Metadata{}) return state } x checkers keeper keeper_integration_test.go View source
  4. Add a simple function to prepare your suite with your desired balances:

    Copy func (suite *IntegrationTestSuite) setupSuiteWithBalances() { suite.app.BankKeeper.InitGenesis(suite.ctx, getBankGenesis()) } x checkers keeper keeper_integration_test.go View source
  5. Add a function to check balances from primitives:

    Copy func (suite *IntegrationTestSuite) RequireBankBalance(expected int, atAddress string) { sdkAdd, err := sdk.AccAddressFromBech32(atAddress) suite.Require().Nil(err, "Address %s failed to parse") suite.Require().Equal( int64(expected), suite.app.BankKeeper.GetBalance(suite.ctx, sdkAdd, sdk.DefaultBondDenom).Amount.Int64()) } x checkers keeper keeper_integration_test.go View source
  6. Update the function(s) you used to set up your keeper with one game, for instance:

    Copy func (suite *IntegrationTestSuite) setupSuiteWithOneGameForPlayMove() { suite.setupSuiteWithBalances() goCtx := sdk.WrapSDKContext(suite.ctx) suite.msgServer.CreateGame(goCtx, &types.MsgCreateGame{ Creator: alice, Red: bob, Black: carol, Wager: 11, }) } x checkers keeper msg_server_play_move_test.go View source

With the preparation done, what does a test method look like?

# Anatomy of an integration suite test

Now you must refactor the existing tests that test your keeper. What does a refactored test look like?

  1. The method declaration:

    Copy func (suite *IntegrationTestSuite) TestCreateGame() x checkers keeper msg_server_create_game_test.go View source

    It is declared as a member of your test suite, and is prefixed with Test (opens new window).

  2. The setup can be done as you like, but since you created a helper you can use it:

    Copy suite.setupSuiteWithBalances() goCtx := sdk.WrapSDKContext(suite.ctx) x checkers keeper msg_server_create_game_test.go View source
  3. The action does not change from before, other than that you get the keeper or msgServer from the suite's fields:

    Copy createResponse, err := suite.msgServer.CreateGame(goCtx, &types.MsgCreateGame{ Creator: alice, Red: bob, Black: carol, Wager: 12, }) x checkers keeper msg_server_create_game_test.go View source
  4. The verification is done with suite.Require().X, but otherwise looks similar to the shorter require.X:

    Copy suite.Require().Nil(err) suite.Require().EqualValues(types.MsgCreateGameResponse{ IdValue: "1", }, *createResponse) x checkers keeper msg_server_create_game_test.go View source

    In fact, it is exactly the same require (opens new window) object. A basic search and replace should work.

  5. If you need access to the checkers keeper, it can also be found in the suite:

    Copy keeper := suite.app.CheckersKeeper nextGame, found := keeper.GetNextGame(suite.ctx) x checkers keeper msg_server_create_game_test.go View source

# What happened to the events?

As you refactor your existing tests, you may notice that the events become messed up. That is because the bank emits events too, and in particular it emits:

  1. An event with the message type, like yours, with only the sender:

    Copy sdk.NewEvent( sdk.EventTypeMessage, sdk.NewAttribute(types.AttributeKeySender, fromAddr.String()), ), x bank keeper send.go View source
  2. An event with the transfer type:

    Copy sdk.NewEvent( types.EventTypeTransfer, sdk.NewAttribute(types.AttributeKeyRecipient, toAddr.String()), sdk.NewAttribute(types.AttributeKeySender, fromAddr.String()), sdk.NewAttribute(sdk.AttributeKeyAmount, amt.String()), ) x bank keeper send.go View source

This means that in your suite.ctx.EventManager().ABCIEvents() there are extra events (opens new window) to account for, and in each case there are extra attributes to discard. Recommended steps:

  1. Make explicit the count of expected attributes for each event type:

    Copy const ( transferEventCount = 3 // As emitted by the bank createEventCount = 7 playEventCountFirst = 8 // Extra "sender" attribute emitted by the bank playEventCountNext = 7 rejectEventCount = 4 rejectEventCountWithTransfer = 5 // Extra "sender" attribute emitted by the bank forfeitEventCount = 4 forfeitEventCountWithTransfer = 5 // Extra "sender" attribute emitted by the bank ) x checkers keeper keeper_integration_test.go View source
  2. Make calculations on the expected count of attributes to discard, depending on the actions previously taken:

    Copy rejectAttributesDiscardCount := createEventCount + playEventCountFirst suite.Require().EqualValues([]sdk.Attribute{ ... {Key: "IdValue", Value: "1"}, }, rejectEvent.Attributes[rejectAttributesDiscardCount:]) x checkers keeper msg_server_reject_game_test.go View source

You can now refactor your tests, which is a substantial task.

# Extra tests

After refactoring, and finding no failing tests, it is time to add extra checks of money handling. For instance, before an action that you expect to transfer money (or not), you can verify the initial position:

Copy suite.RequireBankBalance(balAlice, alice) suite.RequireBankBalance(balBob, bob) suite.RequireBankBalance(balCarol, carol) suite.RequireBankBalance(0, checkersModuleAddress) x checkers keeper msg_server_play_move_test.go View source

After the action you can test the new balances, for instance:

Copy suite.RequireBankBalance(balAlice, alice) suite.RequireBankBalance(balBob, bob) suite.RequireBankBalance(balCarol-11, carol) suite.RequireBankBalance(11, checkersModuleAddress) x checkers keeper msg_server_play_move_test.go View source

How you subdivide your tests and where you insert these balance checks is up to you. You can find examples here for:

# Debug your suite

You learned in a previous section how to launch your test in debug mode. It is still possible to do so when using a suite. The difference is that you launch it by right-clicking on the arrow left of the suite's runner func TestCheckersKeeperTestSuite:

Note that you can only launch debug for all of the suite's test methods and not just a single one (as is possible with a simple test). A solution to this is to create more granular suites, for example using one or more test suites per file.

# Interact via the CLI

Keep the game expiry at 5 minutes to be able to test a forfeit, as done in the previous section. Now, you need to check balances after relevant steps to test that wagers are being withheld and paid.

How much do Alice and Bob have to start with?


Create a game on which the wager will be refunded because the player playing red did not join:

Copy $ checkersd tx checkers create-game $alice $bob 1000000 --from $alice

Which mentions the wager:

Copy ... raw_log: '[{"events":[{"type":"message","attributes":[{"key":"action","value":"CreateGame"},{"key":"module","value":"checkers"},{"key":"action","value":"NewGameCreated"},{"key":"Creator","value":"cosmos1z63q2mn2f6ljm8vfxjzpuz0xthmyx9qd0yy5xr"},{"key":"Index","value":"0"},{"key":"Red","value":"cosmos1z63q2mn2f6ljm8vfxjzpuz0xthmyx9qd0yy5xr"},{"key":"Black","value":"cosmos195e0h5qw44sazd450yt5qvllukcfp7lyc3f9kr"},{"key":"Wager","value":"1000000"}]}]}]'

Confirm that the balances of both Alice and Bob are unchanged - as they have not played yet.

Note: In this example Alice paid no gas fees, other than the transaction costs, to create a game. This is fixed in the next section.

Have Bob play:

Copy $ checkersd tx checkers play-move 0 1 2 2 3 --from $bob

Confirm that Bob has paid his wager:

Copy $ checkersd query bank balances $bob

This prints:

Copy balances: - amount: "99000000" # <- 1,000,000 fewer denom: stake - amount: "10000" denom: token pagination: next_key: null total: "0"

Wait 5 minutes for the game to expire and check again:

Copy $ checkersd query bank balances $bob

This prints:

Copy balances: - amount: "100000000" # <- 1,000,000 are back denom: stake - amount: "10000" denom: token pagination: next_key: null total: "0"

Now create a game in which both players only play once each, i.e. where the player playing black forfeits:

Copy $ checkersd tx checkers create-game $alice $bob 1000000 --from $alice $ checkersd tx checkers play-move 1 1 2 2 3 --from $bob $ checkersd tx checkers play-move 1 0 5 1 4 --from $alice

Confirm that both Alice and Bob paid their wagers. Wait 5 minutes for the game to expire and check again:


This is correct: Alice was the winner by forfeit.

Similarly, you can test that Bob gets his wager back when Alice creates a game, Bob plays, and then Alice rejects it.

It would be difficult to test by CLI when there is a winner after a full game. That would be better tested with a GUI.

# Next up

You can skip ahead and see how to integrate foreign tokens via the use of IBC, or take a look at the next section to prevent spam and reward validators proportional to their effort in your checkers blockchain.