git.delta.rocks / unique-network / refs/commits / bebe624eff63

difftreelog

feat prevent ouroboros creation during nest

Yaroslav Bolyukin2022-04-19parent: #07a6969.patch.diff
in: master

11 files changed

modifiedclient/rpc/src/lib.rsdiffbeforeafterboth
--- a/client/rpc/src/lib.rs
+++ b/client/rpc/src/lib.rs
@@ -77,11 +77,7 @@
 	) -> Result<Vec<u8>>;
 
 	#[rpc(name = "unique_totalSupply")]
-	fn total_supply(
-		&self,
-		collection: CollectionId,
-		at: Option<BlockHash>,
-	) -> Result<u32>;
+	fn total_supply(&self, collection: CollectionId, at: Option<BlockHash>) -> Result<u32>;
 	#[rpc(name = "unique_accountBalance")]
 	fn account_balance(
 		&self,
modifiedpallets/common/src/lib.rsdiffbeforeafterboth
--- a/pallets/common/src/lib.rs
+++ b/pallets/common/src/lib.rs
@@ -918,7 +918,7 @@
 	fn check_nesting(
 		&self,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		budget: &dyn Budget,
 	) -> DispatchResult;
modifiedpallets/fungible/src/common.rsdiffbeforeafterboth
--- a/pallets/fungible/src/common.rs
+++ b/pallets/fungible/src/common.rs
@@ -237,7 +237,7 @@
 	fn check_nesting(
 		&self,
 		_sender: <T>::CrossAccountId,
-		_from: CollectionId,
+		_from: (CollectionId, TokenId),
 		_under: TokenId,
 		_budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/fungible/src/lib.rsdiffbeforeafterboth
--- a/pallets/fungible/src/lib.rs
+++ b/pallets/fungible/src/lib.rs
@@ -224,7 +224,12 @@
 			let dispatch = T::CollectionDispatch::dispatch(handle);
 			let dispatch = dispatch.as_dyn();
 
-			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;
+			dispatch.check_nesting(
+				from.clone(),
+				(collection.id, TokenId::default()),
+				target.1,
+				nesting_budget,
+			)?;
 		}
 
 		// =========
@@ -293,7 +298,12 @@
 				let dispatch = T::CollectionDispatch::dispatch(handle);
 				let dispatch = dispatch.as_dyn();
 
-				dispatch.check_nesting(sender.clone(), collection.id, target.1, nesting_budget)?;
+				dispatch.check_nesting(
+					sender.clone(),
+					(collection.id, TokenId::default()),
+					target.1,
+					nesting_budget,
+				)?;
 			}
 		}
 
@@ -386,10 +396,11 @@
 		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {
 			// TODO: should collection owner be allowed to perform this transfer?
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(
+				<PalletStructure<T>>::check_indirectly_owned(
 					spender.clone(),
 					source.0,
 					source.1,
+					None,
 					nesting_budget
 				)?,
 				<CommonError<T>>::ApprovedValueTooLow,
modifiedpallets/nonfungible/src/common.rsdiffbeforeafterboth
--- a/pallets/nonfungible/src/common.rs
+++ b/pallets/nonfungible/src/common.rs
@@ -251,7 +251,7 @@
 	fn check_nesting(
 		&self,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/nonfungible/src/lib.rsdiffbeforeafterboth
--- a/pallets/nonfungible/src/lib.rs
+++ b/pallets/nonfungible/src/lib.rs
@@ -296,7 +296,12 @@
 			let dispatch = T::CollectionDispatch::dispatch(handle);
 			let dispatch = dispatch.as_dyn();
 
-			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;
+			dispatch.check_nesting(
+				from.clone(),
+				(collection.id, token),
+				target.1,
+				nesting_budget,
+			)?;
 		}
 
 		// =========
@@ -381,13 +386,18 @@
 			);
 		}
 
-		for (to, _) in balances.iter() {
-			if let Some(target) = T::CrossTokenAddressMapping::address_to_token(to) {
+		for (i, data) in data.iter().enumerate() {
+			let token = TokenId(first_token + i as u32 + 1);
+			if let Some(target) = T::CrossTokenAddressMapping::address_to_token(&data.owner) {
 				let handle = <CollectionHandle<T>>::try_get(target.0)?;
 				let dispatch = T::CollectionDispatch::dispatch(handle);
 				let dispatch = dispatch.as_dyn();
-
-				dispatch.check_nesting(sender.clone(), collection.id, target.1, nesting_budget)?;
+				dispatch.check_nesting(
+					sender.clone(),
+					(collection.id, token),
+					target.1,
+					nesting_budget,
+				)?;
 			}
 		}
 
@@ -535,10 +545,11 @@
 		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {
 			// TODO: should collection owner be allowed to perform this transfer?
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(
+				<PalletStructure<T>>::check_indirectly_owned(
 					spender.clone(),
 					source.0,
 					source.1,
+					None,
 					nesting_budget
 				)?,
 				<CommonError<T>>::ApprovedValueTooLow,
@@ -610,31 +621,40 @@
 	pub fn check_nesting(
 		handle: &NonfungibleHandle<T>,
 		sender: T::CrossAccountId,
-		from: CollectionId,
+		from: (CollectionId, TokenId),
 		under: TokenId,
 		nesting_budget: &dyn Budget,
 	) -> DispatchResult {
 		fn ensure_sender_allowed<T: Config>(
 			collection: CollectionId,
 			token: TokenId,
+			for_nest: (CollectionId, TokenId),
 			sender: T::CrossAccountId,
 			budget: &dyn Budget,
 		) -> DispatchResult {
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(sender, collection, token, budget)?,
+				<PalletStructure<T>>::check_indirectly_owned(
+					sender,
+					collection,
+					token,
+					Some(for_nest),
+					budget
+				)?,
 				<CommonError<T>>::OnlyOwnerAllowedToNest,
 			);
 			Ok(())
 		}
 		match handle.limits.nesting_rule() {
 			NestingRule::Disabled => fail!(<CommonError<T>>::NestingIsDisabled),
-			NestingRule::Owner => ensure_sender_allowed::<T>(handle.id, under, sender, nesting_budget)?,
+			NestingRule::Owner => {
+				ensure_sender_allowed::<T>(handle.id, under, from, sender, nesting_budget)?
+			}
 			NestingRule::OwnerRestricted(whitelist) => {
 				ensure!(
-					whitelist.contains(&from),
+					whitelist.contains(&from.0),
 					<CommonError<T>>::SourceCollectionIsNotAllowedToNest
 				);
-				ensure_sender_allowed::<T>(handle.id, under, sender, nesting_budget)?
+				ensure_sender_allowed::<T>(handle.id, under, from, sender, nesting_budget)?
 			}
 		}
 		Ok(())
modifiedpallets/refungible/src/common.rsdiffbeforeafterboth
--- a/pallets/refungible/src/common.rs
+++ b/pallets/refungible/src/common.rs
@@ -260,7 +260,7 @@
 	fn check_nesting(
 		&self,
 		_sender: <T>::CrossAccountId,
-		_from: CollectionId,
+		_from: (CollectionId, TokenId),
 		_under: TokenId,
 		_budget: &dyn Budget,
 	) -> sp_runtime::DispatchResult {
modifiedpallets/refungible/src/lib.rsdiffbeforeafterboth
--- a/pallets/refungible/src/lib.rs
+++ b/pallets/refungible/src/lib.rs
@@ -352,7 +352,12 @@
 			let dispatch = T::CollectionDispatch::dispatch(handle);
 			let dispatch = dispatch.as_dyn();
 
-			dispatch.check_nesting(from.clone(), collection.id, target.1, nesting_budget)?;
+			dispatch.check_nesting(
+				from.clone(),
+				(collection.id, token),
+				target.1,
+				nesting_budget,
+			)?;
 		}
 
 		// =========
@@ -455,7 +460,8 @@
 			}
 		}
 
-		for token in data.iter() {
+		for (i, token) in data.iter().enumerate() {
+			let token_id = TokenId(first_token_id + i as u32 + 1);
 			for (to, _) in token.users.iter() {
 				if let Some(target) = T::CrossTokenAddressMapping::address_to_token(to) {
 					let handle = <CollectionHandle<T>>::try_get(target.0)?;
@@ -464,7 +470,7 @@
 
 					dispatch.check_nesting(
 						sender.clone(),
-						collection.id,
+						(collection.id, token_id),
 						target.1,
 						nesting_budget,
 					)?;
@@ -575,10 +581,11 @@
 		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {
 			// TODO: should collection owner be allowed to perform this transfer?
 			ensure!(
-				<PalletStructure<T>>::indirectly_owned(
+				<PalletStructure<T>>::check_indirectly_owned(
 					spender.clone(),
 					source.0,
 					source.1,
+					None,
 					nesting_budget
 				)?,
 				<CommonError<T>>::ApprovedValueTooLow,
modifiedpallets/structure/src/lib.rsdiffbeforeafterboth
--- a/pallets/structure/src/lib.rs
+++ b/pallets/structure/src/lib.rs
@@ -71,7 +71,7 @@
 #[derive(PartialEq)]
 pub enum Parent<CrossAccountId> {
 	/// Token owned by normal account
-	Normal(CrossAccountId),
+	User(CrossAccountId),
 	/// Passed token not found
 	TokenNotFound,
 	/// Token owner is another token (target token still may not exist)
@@ -94,7 +94,7 @@
 		Ok(match handle.token_owner(token) {
 			Some(owner) => match T::CrossTokenAddressMapping::address_to_token(&owner) {
 				Some((collection, token)) => Parent::Token(collection, token),
-				None => Parent::Normal(owner),
+				None => Parent::User(owner),
 			},
 			None => Parent::TokenNotFound,
 		})
@@ -137,29 +137,46 @@
 	) -> Result<T::CrossAccountId, DispatchError> {
 		let owner = Self::parent_chain(collection, token)
 			.take_while(|_| budget.consume())
-			.find(|p| matches!(p, Ok(Parent::Normal(_) | Parent::TokenNotFound)))
+			.find(|p| matches!(p, Ok(Parent::User(_) | Parent::TokenNotFound)))
 			.ok_or(<Error<T>>::DepthLimit)??;
 
 		Ok(match owner {
-			Parent::Normal(v) => v,
+			Parent::User(v) => v,
 			_ => fail!(<Error<T>>::TokenNotFound),
 		})
 	}
 
 	/// Check if token indirectly owned by specified user
-	pub fn indirectly_owned(
+	pub fn check_indirectly_owned(
 		user: T::CrossAccountId,
 		collection: CollectionId,
 		token: TokenId,
+		for_nest: Option<(CollectionId, TokenId)>,
 		budget: &dyn Budget,
 	) -> Result<bool, DispatchError> {
 		let target_parent = match T::CrossTokenAddressMapping::address_to_token(&user) {
 			Some((collection, token)) => Parent::Token(collection, token),
-			None => Parent::Normal(user),
+			None => Parent::User(user),
 		};
 
-		Ok(Self::parent_chain(collection, token)
-			.take_while(|_| budget.consume())
-			.any(|parent| Ok(&target_parent) == parent.as_ref()))
+		// Tried to nest token in itself
+		if Some((collection, token)) == for_nest {
+			return Err(<Error<T>>::OuroborosDetected.into());
+		}
+
+		for parent in Self::parent_chain(collection, token).take_while(|_| budget.consume()) {
+			match parent? {
+				// Tried to nest token in chain, which has this token as one of parents
+				Parent::Token(collection, token) if Some((collection, token)) == for_nest => {
+					return Err(<Error<T>>::OuroborosDetected.into())
+				}
+				// Found needed parent, token is indirecty owned
+				v if v == target_parent => return Ok(true),
+				Parent::TokenNotFound => return Ok(false),
+				_ => {}
+			}
+		}
+
+		Err(<Error<T>>::DepthLimit.into())
 	}
 }
modifiedtests/src/eth/util/helpers.tsdiffbeforeafterboth
before · tests/src/eth/util/helpers.ts
1// Copyright 2019-2022 Unique Network (Gibraltar) Ltd.2// This file is part of Unique Network.34// Unique Network is free software: you can redistribute it and/or modify5// it under the terms of the GNU General Public License as published by6// the Free Software Foundation, either version 3 of the License, or7// (at your option) any later version.89// Unique Network is distributed in the hope that it will be useful,10// but WITHOUT ANY WARRANTY; without even the implied warranty of11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the12// GNU General Public License for more details.1314// You should have received a copy of the GNU General Public License15// along with Unique Network. If not, see <http://www.gnu.org/licenses/>.1617// eslint-disable-next-line @typescript-eslint/triple-slash-reference18/// <reference path="helpers.d.ts" />1920import {ApiPromise} from '@polkadot/api';21import {addressToEvm, evmToAddress} from '@polkadot/util-crypto';22import Web3 from 'web3';23import usingApi, {submitTransactionAsync} from '../../substrate/substrate-api';24import {IKeyringPair} from '@polkadot/types/types';25import {expect} from 'chai';26import {getGenericResult, UNIQUE} from '../../util/helpers';27import * as solc from 'solc';28import config from '../../config';29import privateKey from '../../substrate/privateKey';30import contractHelpersAbi from './contractHelpersAbi.json';31import getBalance from '../../substrate/get-balance';32import waitNewBlocks from '../../substrate/wait-new-blocks';3334export const GAS_ARGS = {gas: 2500000};3536export enum SponsoringMode {37  Disabled = 0,38  Allowlisted = 1,39  Generous = 2,40}4142let web3Connected = false;43export async function usingWeb3<T>(cb: (web3: Web3) => Promise<T> | T): Promise<T> {44  if (web3Connected) throw new Error('do not nest usingWeb3 calls');45  web3Connected = true;4647  const provider = new Web3.providers.WebsocketProvider(config.substrateUrl);48  const web3 = new Web3(provider);4950  try {51    return await cb(web3);52  } finally {53    // provider.disconnect(3000, 'normal disconnect');54    provider.connection.close();55    web3Connected = false;56  }57}5859function encodeIntBE(v: number): number[] {60  if (v >= 0xffffffff || v < 0) throw new Error('id overflow');61  return [62    v >> 24,63    (v >> 16) & 0xff,64    (v >> 8) & 0xff,65    v & 0xff,66  ];67}6869export function collectionIdToAddress(collection: number): string {70  const buf = Buffer.from([0x17, 0xc4, 0xe6, 0x45, 0x3c, 0xc4, 0x9a, 0xaa, 0xae, 0xac, 0xa8, 0x94, 0xe6, 0xd9, 0x68, 0x3e,71    ...encodeIntBE(collection),72  ]);73  return Web3.utils.toChecksumAddress('0x' + buf.toString('hex'));74}7576export function tokenIdToAddress(collection: number, token: number): string {77  const buf = Buffer.from([0xf8, 0x23, 0x8c, 0xcf, 0xff, 0x8e, 0xd8, 0x87, 0x46, 0x3f, 0xd5, 0xe0,78    ...encodeIntBE(collection),79    ...encodeIntBE(token),80  ]);81  return Web3.utils.toChecksumAddress('0x' + buf.toString('hex'));82}8384export function createEthAccount(web3: Web3) {85  const account = web3.eth.accounts.create();86  web3.eth.accounts.wallet.add(account.privateKey);87  return account.address;88}8990export async function createEthAccountWithBalance(api: ApiPromise, web3: Web3) {91  const alice = privateKey('//Alice');92  const account = createEthAccount(web3);93  await transferBalanceToEth(api, alice, account);9495  return account;96}9798export async function transferBalanceToEth(api: ApiPromise, source: IKeyringPair, target: string, amount = 1000n * UNIQUE) {99  const tx = api.tx.balances.transfer(evmToAddress(target), amount);100  const events = await submitTransactionAsync(source, tx);101  const result = getGenericResult(events);102  expect(result.success).to.be.true;103}104105export async function itWeb3(name: string, cb: (apis: { web3: Web3, api: ApiPromise }) => any, opts: { only?: boolean, skip?: boolean } = {}) {106  let i: any = it;107  if (opts.only) i = i.only;108  else if (opts.skip) i = i.skip;109  i(name, async () => {110    await usingApi(async api => {111      await usingWeb3(async web3 => {112        await cb({api, web3});113      });114    });115  });116}117itWeb3.only = (name: string, cb: (apis: { web3: Web3, api: ApiPromise }) => any) => itWeb3(name, cb, {only: true});118itWeb3.skip = (name: string, cb: (apis: { web3: Web3, api: ApiPromise }) => any) => itWeb3(name, cb, {skip: true});119120export async function generateSubstrateEthPair(web3: Web3) {121  const account = web3.eth.accounts.create();122  evmToAddress(account.address);123}124125type NormalizedEvent = {126    address: string,127    event: string,128    args: { [key: string]: string }129};130131export function normalizeEvents(events: any): NormalizedEvent[] {132  const output = [];133  for (const key of Object.keys(events)) {134    if (key.match(/^[0-9]+$/)) {135      output.push(events[key]);136    } else if (Array.isArray(events[key])) {137      output.push(...events[key]);138    } else {139      output.push(events[key]);140    }141  }142  output.sort((a, b) => a.logIndex - b.logIndex);143  return output.map(({address, event, returnValues}) => {144    const args: { [key: string]: string } = {};145    for (const key of Object.keys(returnValues)) {146      if (!key.match(/^[0-9]+$/)) {147        args[key] = returnValues[key];148      }149    }150    return {151      address,152      event,153      args,154    };155  });156}157158export async function recordEvents(contract: any, action: () => Promise<void>): Promise<NormalizedEvent[]> {159  const out: any = [];160  contract.events.allEvents((_: any, event: any) => {161    out.push(event);162  });163  await action();164  return normalizeEvents(out);165}166167export function subToEthLowercase(eth: string): string {168  const bytes = addressToEvm(eth);169  return '0x' + Buffer.from(bytes).toString('hex');170}171172export function subToEth(eth: string): string {173  return Web3.utils.toChecksumAddress(subToEthLowercase(eth));174}175176export function compileContract(name: string, src: string) {177  const out = JSON.parse(solc.compile(JSON.stringify({178    language: 'Solidity',179    sources: {180      [`${name}.sol`]: {181        content: `182          // SPDX-License-Identifier: UNLICENSED183          pragma solidity ^0.8.6;184185          ${src}186        `,187      },188    },189    settings: {190      outputSelection: {191        '*': {192          '*': ['*'],193        },194      },195    },196  }))).contracts[`${name}.sol`][name];197198  return {199    abi: out.abi,200    object: '0x' + out.evm.bytecode.object,201  };202}203204export async function deployFlipper(web3: Web3, deployer: string) {205  const compiled = compileContract('Flipper', `206    contract Flipper {207      bool value = false;208      function flip() public {209        value = !value;210      }211      function getValue() public view returns (bool) {212        return value;213      }214    }215  `);216  const flipperContract = new web3.eth.Contract(compiled.abi, undefined, {217    data: compiled.object,218    from: deployer,219    ...GAS_ARGS,220  });221  const flipper = await flipperContract.deploy({data: compiled.object}).send({from: deployer});222223  return flipper;224}225226export async function deployCollector(web3: Web3, deployer: string) {227  const compiled = compileContract('Collector', `228    contract Collector {229      uint256 collected;230      fallback() external payable {231        giveMoney();232      }233      function giveMoney() public payable {234        collected += msg.value;235      }236      function getCollected() public view returns (uint256) {237        return collected;238      }239      function getUnaccounted() public view returns (uint256) {240        return address(this).balance - collected;241      }242243      function withdraw(address payable target) public {244        target.transfer(collected);245        collected = 0;246      }247    }248  `);249  const collectorContract = new web3.eth.Contract(compiled.abi, undefined, {250    data: compiled.object,251    from: deployer,252    ...GAS_ARGS,253  });254  const collector = await collectorContract.deploy({data: compiled.object}).send({from: deployer});255256  return collector;257}258259/** 260 * pallet evm_contract_helpers261 * @param web3 262 * @param caller - eth address263 * @returns 264 */265export function contractHelpers(web3: Web3, caller: string) {266  return new web3.eth.Contract(contractHelpersAbi as any, '0x842899ECF380553E8a4de75bF534cdf6fBF64049', {from: caller, ...GAS_ARGS});267}268269/**270 * Execute ethereum method call using substrate account271 * @param to target contract272 * @param mkTx - closure, receiving `contract.methods`, and returning method call,273 * to be used as following (assuming `to` = erc20 contract):274 * `m => m.transfer(to, amount)`275 *276 * # Example277 * ```ts278 * executeEthTxOnSub(api, alice, erc20Contract, m => m.transfer(target, amount));279 * ```280 */281export async function executeEthTxOnSub(web3: Web3, api: ApiPromise, from: IKeyringPair, to: any, mkTx: (methods: any) => any, {value = 0}: {value?: bigint | number} = { }) {282  const tx = api.tx.evm.call(283    subToEth(from.address),284    to.options.address,285    mkTx(to.methods).encodeABI(),286    value,287    GAS_ARGS.gas,288    await web3.eth.getGasPrice(),289    null,290    null,291    [],292  );293  const events = await submitTransactionAsync(from, tx);294  expect(events.some(({event: {section, method}}) => section == 'evm' && method == 'Executed')).to.be.true;295}296297export async function ethBalanceViaSub(api: ApiPromise, address: string): Promise<bigint> {298  return (await getBalance(api, [evmToAddress(address)]))[0];299}300301/**302 * Measure how much gas given closure consumes303 *304 * @param user which user balance will be checked305 */306export async function recordEthFee(api: ApiPromise, user: string, call: () => Promise<any>): Promise<bigint> {307  const before = await ethBalanceViaSub(api, user);308309  await call();310311  // In dev mode, the transaction might not finish processing in time312  await waitNewBlocks(api, 1);313  const after = await ethBalanceViaSub(api, user);314315  // Can't use .to.be.less, because chai doesn't supports bigint316  expect(after < before).to.be.true;317318  return before - after;319}
addedtests/src/nesting/graphs.test.tsdiffbeforeafterboth
--- /dev/null
+++ b/tests/src/nesting/graphs.test.ts
@@ -0,0 +1,51 @@
+import {ApiPromise} from '@polkadot/api';
+import {IKeyringPair} from '@polkadot/types/types';
+import {expect} from 'chai';
+import {tokenIdToCross} from '../eth/util/helpers';
+import privateKey from '../substrate/privateKey';
+import usingApi, {executeTransaction} from '../substrate/substrate-api';
+import {getCreateCollectionResult, transferExpectSuccess} from '../util/helpers';
+
+/**
+ * ```dot
+ * 4 -> 3 -> 2 -> 1
+ * 7 -> 6 -> 5 -> 2
+ * 8 -> 5
+ * ```
+ */
+async function buildComplexObjectGraph(api: ApiPromise, sender: IKeyringPair): Promise<number> {
+  const events = await executeTransaction(api, sender, api.tx.unique.createCollectionEx({mode: 'NFT'}));
+  const {collectionId} = getCreateCollectionResult(events);
+
+  await executeTransaction(api, sender, api.tx.unique.createMultipleItemsEx(collectionId, {NFT: Array(8).fill({owner: {Substrate: sender.address}})}));
+
+  await transferExpectSuccess(collectionId, 8, sender, tokenIdToCross(collectionId, 5));
+
+  await transferExpectSuccess(collectionId, 7, sender, tokenIdToCross(collectionId, 6));
+  await transferExpectSuccess(collectionId, 6, sender, tokenIdToCross(collectionId, 5));
+  await transferExpectSuccess(collectionId, 5, sender, tokenIdToCross(collectionId, 2));
+
+  await transferExpectSuccess(collectionId, 4, sender, tokenIdToCross(collectionId, 3));
+  await transferExpectSuccess(collectionId, 3, sender, tokenIdToCross(collectionId, 2));
+  await transferExpectSuccess(collectionId, 2, sender, tokenIdToCross(collectionId, 1));
+
+  return collectionId;
+}
+
+describe('graphs', () => {
+  it('ouroboros can\'t be created in graph', async () => {
+    await usingApi(async api => {
+      const alice = privateKey('//Alice');
+      const collection = await buildComplexObjectGraph(api, alice);
+
+      // to self
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 1), collection, 1, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+      // to nested part of graph
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 5), collection, 1, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+      await expect(executeTransaction(api, alice, api.tx.unique.transfer(tokenIdToCross(collection, 8), collection, 2, 1)))
+        .to.be.rejectedWith(/structure\.OuroborosDetected/);
+    });
+  });
+});