Matchstick: Assertion error: expected field equal '' but was '' - graphql

Question

During testing my Graph Project I receive the following error:
nft-lottery
Player entity
𝖷 (assert.fieldEquals) Expected field 'lotteries' to equal '[0x1]', but was '[]' instead.
🛠 Mapping aborted at ~lib/matchstick-as/assembly/assert.ts, line 13, column 7, with message: Assertion Error
wasm backtrace:
0: 0x387c - <unknown>!~lib/matchstick-as/assembly/assert/assert.fieldEquals
1: 0x38fa - <unknown>!start:tests/nft-lottery.test~anonymous|0~anonymous|3
If I log the results after calling handleNftLotteryEnter() function I get (i.e., the lottery.id has not been stored even though it should have as it is derivedFrom the NftLottery - see below):
"Player": {
"0xdb...a7bf": {
"lotteries": {
"type": "List",
"data": []
}
}
},
...
If I try to mock firing three subsequent events, the first two players has got values stored but the last one has not, i.e.:
"Player": {
"0x5a...3ca1": {
"lotteries": {
"type": "List",
"data": [
{
"type": "String",
"data": "0x1"
}
]
}
},
"0xd1...6575": {
"lotteries": {
"type": "List",
"data": []
}
},
"0xdb...a7bf": {
"lotteries": {
"type": "List",
"data": [
{
"type": "String",
"data": "0x1"
}
]
}
}
},
What could be the reason thereof?
Thank you in advance!
Test file
import {
assert,
describe,
test,
clearStore,
beforeAll,
afterAll,
logStore,
} from "matchstick-as/assembly/index"
import { BigInt, Address } from "#graphprotocol/graph-ts"
import { handleNftLotteryEnter } from "../src/nft-lottery"
import { createNftLotteryEnterEvent } from "./nft-lottery-utils"
describe("Enter the NFT Lottery 1x", () => {
beforeAll(() => {
let lotteryCounter = BigInt.fromI32(1)
let player_one = Address.fromString("0xDB...a7bf")
let entranceFee = BigInt.fromI32(1)
let newNftLotteryEnterEvent = createNftLotteryEnterEvent(
lotteryCounter,
player_one,
entranceFee
)
handleNftLotteryEnter(newNftLotteryEnterEvent)
logStore()
})
afterAll(() => {
clearStore()
})
test("Player entity", () => {
assert.fieldEquals("Player", "0xdb...a7bf", "lotteries", "[0x1]")
})
})
describe("Enter the NFT Lottery 3x", () => {
beforeAll(() => {
let lotteryCounter = BigInt.fromI32(1)
let entranceFee = BigInt.fromI32(1)
let player_one = Address.fromString("0xDB...a7bf")
let player_two = Address.fromString("0x5a...3cA1")
let player_three = Address.fromString("0xd1...6575")
// the first event
let oneNftLotteryEnterEvent = createNftLotteryEnterEvent(
lotteryCounter,
player_one,
entranceFee
)
handleNftLotteryEnter(oneNftLotteryEnterEvent)
// the second event
let twoNftLotteryEnterEvent = createNftLotteryEnterEvent(
lotteryCounter,
player_two,
entranceFee
)
// the third event
handleNftLotteryEnter(twoNftLotteryEnterEvent)
let threeNftLotteryEnterEvent = createNftLotteryEnterEvent(
lotteryCounter,
player_three,
entranceFee
)
handleNftLotteryEnter(threeNftLotteryEnterEvent)
logStore()
})
afterAll(() => {
clearStore()
})
test("Counts", () => {
assert.entityCount("NftLottery", 1)
assert.entityCount("Player", 3)
})
test("Player Entity 3x", () => {
assert.fieldEquals("Player", "0xdb...a7bf", "lotteries", "[0x1]")
})
})
Schema.graphql
type NftLottery #entity {
id: ID!
openAtTimestamp: BigInt!
closeAtTimestamp: BigInt!
prize: BigInt!
players: [Player!]!
winners: [Player!]
requestId: BigInt
updatedAtTimestamp: BigInt
}
type Player #entity {
id: ID! # address
lotteries: [NftLottery!]! #derivedFrom(field: "players")
}
# events
type NftLotteryEnter #entity {
id: ID! # Set lotteryCounter + playerAddress
lotteryCounter: BigInt!
player: Bytes!
numberOfEntrances: [BigInt!]!
updatedAtTimestamp: BigInt
}
Handlers
import { BigInt, Address } from "#graphprotocol/graph-ts"
import {
NftLotteryEnter as NftLotteryEnterEvent
} from "../generated/NftLottery/NftLottery"
import { NftLottery, Player, NftLotteryEnter } from "../generated/schema"
export function handleNftLotteryEnter(event: NftLotteryEnterEvent): void {
/* Event params */
const playerId = event.params.player.toHexString()
const lotteryId = event.params.lotteryCounter.toHexString()
const entranceFee = event.params.entranceFee.toString()
const lotteryPlayerId = lotteryId + playerId
/* NftLottery: if a lottery does not exist, create it */
let nftLottery = NftLottery.load(lotteryId)
if (!nftLottery) {
nftLottery = new NftLottery(lotteryId)
nftLottery.openAtTimestamp = event.block.timestamp
nftLottery.closeAtTimestamp = BigInt.fromString("000000000000")
nftLottery.requestId = BigInt.fromString("0")
nftLottery.prize = BigInt.fromString("0")
nftLottery.players = new Array<string>()
nftLottery.winners = new Array<string>()
}
// update lottery data
let currentPrize = nftLottery.prize
nftLottery.prize = currentPrize.plus(BigInt.fromString(entranceFee))
// update players
let arrPlayers = nftLottery.players
arrPlayers.push(playerId)
nftLottery.players = arrPlayers
nftLottery.updatedAtTimestamp = event.block.timestamp
nftLottery.save()
/* Player: if a player does not exist, create them */
let player = Player.load(playerId)
if (!player) {
player = new Player(playerId)
player.save()
}
/* NftLotteryEnter */
let nftLotteryEnter = NftLotteryEnter.load((lotteryPlayerId))
if (!nftLotteryEnter) {
nftLotteryEnter = new NftLotteryEnter(lotteryPlayerId)
nftLotteryEnter.lotteryCounter = BigInt.fromString(event.params.lotteryCounter.toString())
nftLotteryEnter.player = Address.fromHexString(playerId)
nftLotteryEnter.numberOfEntrances = BigInt.fromString("0")
}
// update entrances
const entrances = nftLotteryEnter.numberOfEntrances
nftLotteryEnter.numberOfEntrances = entrances.plus(BigInt.fromString("1"))
nftLotteryEnter.save()
}

Answer 1

There might be a bug in Matchstick testing tool:
As PlayerEntity derives lotteries from NftLottery, the NftLottery should be saved AT THE END of all operations related to both entities.
Otherwise Player.lotteries does not get updated immediately and it stays empty, thus test fails.
...
// update when updated
nftLottery.updatedAtTimestamp = event.block.timestamp
/* Player: if a player does not exist, create them */
let player = Player.load(playerId)
if (!player) {
player = new Player(playerId)
player.save()
}
nftLottery.save()
...
Credit goes to Maks#3349 at unit testing of Graph discord.