> ## Documentation Index > Fetch the complete documentation index at: https://docs.cow.bleu.builders/llms.txt > Use this file to discover all available pages before exploring further. # Testing Your Integration > Step-by-step guide to testing your CoW Protocol integration — from getting test tokens on Sepolia to verifying orders settle, then graduating to mainnet. export const InlineResource = ({value, copyValue, href, chain, explorerHref, explorerType = "address", explorerSuffix = "", showCopy = true, showExplorer = false, openInNewTab}) => { const explorerBases = { arbitrum: "https://arbiscan.io", arbitrum_one: "https://arbiscan.io", avalanche: "https://snowscan.xyz", base: "https://basescan.org", bnb: "https://bscscan.com", ethereum: "https://etherscan.io", gnosis: "https://gnosisscan.io", ink: "https://explorer.inkonchain.com", linea: "https://lineascan.build", mainnet: "https://etherscan.io", optimism: "https://optimistic.etherscan.io", plasma: "https://plasmascan.to", polygon: "https://polygonscan.com", sepolia: "https://sepolia.etherscan.io", xdai: "https://gnosisscan.io" }; const isExternalUrl = (candidate = "") => (/^https?:\/\//i).test(candidate); const isHexAddress = (candidate = "") => (/^0x[a-fA-F0-9]{40}$/).test(candidate); const normalizeUrl = (candidate = "") => { if (!candidate) { return ""; } if (candidate.startsWith("/") || candidate.startsWith("#") || isExternalUrl(candidate)) { return candidate; } return `https://${candidate}`; }; const compactUrl = (candidate = "") => { const withoutProtocol = candidate.replace(/^https?:\/\//i, ""); if (withoutProtocol.length <= 40) { return withoutProtocol; } const [host, ...segments] = withoutProtocol.split("/"); if (!segments.length) { return `${withoutProtocol.slice(0, 20)}...${withoutProtocol.slice(-12)}`; } const tail = segments.length >= 2 ? `${segments[segments.length - 2]}/${segments[segments.length - 1]}` : segments[segments.length - 1]; return `${host}/.../${tail}`; }; const resolvedExplorerHref = (() => { if (explorerHref) { return explorerHref; } if (!chain || !value) { return ""; } const base = explorerBases[chain]; if (!base) { return ""; } return `${base}/${explorerType}/${value}${explorerSuffix}`; })(); const resolvedHref = normalizeUrl(href || ""); const primaryHref = resolvedHref || (showExplorer ? resolvedExplorerHref : ""); const primaryTarget = openInNewTab ?? (primaryHref ? isExternalUrl(primaryHref) : false); const shouldCompactValue = isExternalUrl(value || "") || isExternalUrl(primaryHref); const displayValue = shouldCompactValue ? compactUrl(value) : value; const contentClassName = ["inline-resource__value", shouldCompactValue ? "inline-resource__value--compact" : "", isHexAddress(value || "") ? "inline-resource__value--address" : ""].filter(Boolean).join(" "); const setButtonState = (button, state, label) => { if (!button) { return; } button.dataset.state = state; button.setAttribute("aria-label", label); button.title = label; if (button.__copyTimer) { window.clearTimeout(button.__copyTimer); button.__copyTimer = null; } if (state === "idle") { return; } button.__copyTimer = window.setTimeout(() => { button.dataset.state = "idle"; button.setAttribute("aria-label", "Copy value"); button.title = "Copy value"; }, 1200); }; const fallbackCopy = text => { if (typeof document === "undefined") { return false; } const input = document.createElement("textarea"); input.value = text; input.setAttribute("readonly", ""); input.style.left = "-9999px"; input.style.position = "absolute"; document.body.appendChild(input); input.select(); let copied = false; try { copied = document.execCommand("copy"); } catch { copied = false; } document.body.removeChild(input); return copied; }; const copyText = async (text, button) => { if (!text) { setButtonState(button, "copied", "Nothing to copy"); return; } try { if (typeof navigator !== "undefined" && navigator.clipboard?.writeText) { await navigator.clipboard.writeText(text); setButtonState(button, "copied", "Copied"); return; } } catch {} const copied = fallbackCopy(text); setButtonState(button, copied ? "copied" : "idle", copied ? "Copied" : "Copy failed"); }; const content = {displayValue} ; return {primaryHref ? {content} : content} {showCopy || showExplorer && resolvedExplorerHref && resolvedExplorerHref !== primaryHref ? {showCopy ? : null} {showExplorer && resolvedExplorerHref && resolvedExplorerHref !== primaryHref ? : null} : null} ; }; ## Overview This guide walks you through testing a CoW Protocol integration end-to-end. You'll place a real order on the Sepolia testnet, verify it settles, and then move to production. ## Step 1: Set Up Your Test Environment ### Contract addresses CoW Protocol is deployed on **Sepolia** with the same addresses as mainnet: | Contract | Address | | ---------------- | -------------------------------------------------------------------------------------------------- | | GPv2Settlement | | | GPv2VaultRelayer | | ### API endpoint Sepolia API base URL: ### SDK configuration ```typescript theme={null} import { SupportedChainId, TradingSdk } from '@cowprotocol/sdk-trading' const sdk = new TradingSdk({ chainId: SupportedChainId.SEPOLIA, appCode: 'my-app-testing', }, {}, adapter) ``` ## Step 2: Get Test Tokens You need Sepolia ETH and ERC-20 tokens to test with. ### Get Sepolia ETH Use a faucet: * [sepoliafaucet.com](https://sepoliafaucet.com) * [Alchemy Sepolia Faucet](https://www.alchemy.com/faucets/ethereum-sepolia) ### Get test ERC-20s 1. **Wrap ETH to WETH**: Send ETH to the WETH contract (`0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14`) or use CoW Swap on Sepolia 2. **Swap for test tokens**: Use CoW Swap (Sepolia) or Uniswap (Sepolia) to swap WETH for COW or USDC ### Example token addresses These are the Sepolia token addresses used in the examples below: | Token | Sepolia Address | | ----- | -------------------------------------------------------------------------------------------------- | | WETH | | | COW | | ## Step 3: Approve the Vault Relayer Before placing orders, approve the GPv2VaultRelayer to spend your sell token. This is a one-time step per token. **With Foundry:** ```bash theme={null} cast send 0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14 \ "approve(address,uint256)" \ 0xC92E8bdf79f0507f65a392b0ab4667716BFE0110 \ 115792089237316195423570985008687907853269984665640564039457584007913129639935 \ --rpc-url https://rpc.sepolia.org \ --private-key $PRIVATE_KEY ``` **With the SDK:** ```typescript theme={null} import { maxUint256 } from 'viem' const txHash = await sdk.approveCowProtocol({ tokenAddress: '0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14', amount: maxUint256, }) ``` **Verify it worked:** ```bash theme={null} cast call 0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14 \ "allowance(address,address)(uint256)" \ $YOUR_ADDRESS \ 0xC92E8bdf79f0507f65a392b0ab4667716BFE0110 \ --rpc-url https://rpc.sepolia.org ``` The output should be a large number (max uint256 if you used infinite approval). ## Step 4: Place a Test Order ### Using the API ```bash theme={null} # 1. Get a quote curl -X POST "https://api.cow.fi/sepolia/api/v1/quote" \ -H "Content-Type: application/json" \ -d '{ "sellToken": "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14", "buyToken": "0xbe72E441BF55620febc26715db68d3494213D8Cb", "sellAmountBeforeFee": "100000000000000000", "kind": "sell", "from": "YOUR_ADDRESS", "receiver": "YOUR_ADDRESS", "validFor": 1800, "signingScheme": "eip712", "appData": "{}", "appDataHash": "0xb48d38f93eaa084033fc5970bf96e559c33c4cdc07d889ab00b4d63f9590739d" }' ``` The quote response includes: * `quote.appData` and `quote.appDataHash` — sign the hash, submit the JSON `appData` * `id` — pass it later as `quoteId` * `expiration` — submit before this timestamp Then complete the happy path with [Step 5: Sign the Order](/cow-protocol/howto/integrate/api#step-5-sign-the-order) and [Step 6: Submit the Order](/cow-protocol/howto/integrate/api#step-6-submit-the-order). ### Using the SDK ```typescript theme={null} import { OrderKind } from '@cowprotocol/sdk-trading' const { orderId } = await sdk.postSwapOrder({ kind: OrderKind.SELL, sellToken: '0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14', sellTokenDecimals: 18, buyToken: '0xbe72E441BF55620febc26715db68d3494213D8Cb', buyTokenDecimals: 18, amount: '100000000000000000', // 0.1 WETH slippageBps: 500, // 5% — use wide slippage on testnet validFor: 1800, // 30 minutes }) console.log('Order UID:', orderId) ``` ## Step 5: Verify the Order ### Check order status ```bash theme={null} curl "https://api.cow.fi/sepolia/api/v1/orders/ORDER_UID" ``` Or with the SDK: ```typescript theme={null} const order = await sdk.getOrder({ orderUid: orderId }) console.log('Status:', order.status) ``` ### Check the Explorer Open `https://explorer.cow.fi/sepolia/orders/{ORDER_UID}` in your browser. You should see your order with its current status. ### Expected behavior | Status | What it means | What to do | | ----------- | ----------------------------------------- | --------------------------------------- | | `open` | Order is in the book, waiting for solvers | Wait — Sepolia may take several minutes | | `fulfilled` | Order settled on-chain | Success — check `executedBuyAmount` | | `expired` | Order timed out | See troubleshooting below | | `cancelled` | You cancelled it | Expected if you called cancel | ### Verify the trade Once status is `fulfilled`: ```bash theme={null} curl "https://api.cow.fi/sepolia/api/v2/trades?orderUid=ORDER_UID" ``` Check that `txHash` is present and the `buyAmount` is reasonable. ## Step 6: Test Edge Cases Before going to production, verify these scenarios: | Test | What to verify | | -------------------------- | ---------------------------------------------------------------------------------------------------------------------- | | **Buy order** | Change `kind` to `"buy"` and use `buyAmountAfterFee` instead of `sellAmountBeforeFee` | | **Cancellation** | Create an order with long `validFor`, then cancel it with `DELETE /api/v1/orders/{UID}` or `sdk.offChainCancelOrder()` | | **Insufficient balance** | Try placing an order with more tokens than you hold — should get `InsufficientBalance` error | | **Insufficient allowance** | Revoke approval, then try placing an order — should get `InsufficientAllowance` error | | **Expired quote** | Wait for the quote to expire, then try submitting — should get a rejection | | **Status polling** | Set up a loop that checks order status every 10 seconds until `fulfilled` or `expired` | ## Step 7: Graduate to Production ### Recommended progression 1. **Sepolia** — verify signing, order creation, and status polling work end-to-end 2. **Barn (mainnet staging)** — test with real liquidity using small amounts 3. **Production** — switch to `api.cow.fi/mainnet` with production amounts ### Using barn (mainnet staging) Barn is the staging endpoint for mainnet: With the SDK: ```typescript theme={null} const parameters: TradeParameters = { env: 'staging', // Uses barn API kind: OrderKind.SELL, // ... rest of parameters } ``` **Barn targets mainnet.** Orders placed there use mainnet assets and can settle on-chain if filled, so test with small amounts. ### Production checklist Before going live: * [ ] Orders create and settle correctly on Sepolia * [ ] Signing works with your chosen `signingScheme` * [ ] Status polling correctly detects `fulfilled`, `expired`, and `cancelled` * [ ] Error handling catches `InsufficientBalance`, `InsufficientAllowance`, `InvalidSignature` * [ ] Cancellation flow works * [ ] (Optional) Tested on barn with small mainnet amounts ### Switching to production Change the API base URL to . Or with the SDK, remove the `env: 'staging'` parameter (production is the default). ## Sepolia Notes Sepolia is useful for verifying your integration flow, but quote quality and fill behavior can differ from mainnet. If you need mainnet conditions, test on barn with small amounts. ### Practical testing tips 1. Use the token addresses listed above so your quote and signing examples match the guide. 2. If a quote expires before submission, request a fresh quote and retry immediately. 3. If an order stays `open` until `validTo`, retry with adjusted order parameters or continue testing on barn. 4. Keep test amounts small when moving from Sepolia to barn or mainnet. ## Troubleshooting | Issue | Cause | Fix | | --------------------------------- | ------------------------------------------------- | ------------------------------------------------------------------------ | | Order expires unfilled | The order did not settle before `validTo` | Re-quote and retry, or adjust the order parameters | | `NoLiquidity` error | The requested pair could not be quoted on Sepolia | Try a different supported pair | | `SellAmountDoesNotCoverFee` | Gas costs high relative to small test amounts | Increase the sell amount | | `InvalidSignature` error | EIP-712 domain or struct mismatch | Verify `chainId: 11155111` for Sepolia, check order fields exactly match | | Order shows `presignaturePending` | PreSign transaction not confirmed | Wait for Sepolia block confirmation, check tx hash | | Different results than mainnet | Testnet conditions differ from mainnet | Expected — use barn for mainnet testing | | `InsufficientAllowance` on barn | Forgot to approve on mainnet | Approve the Vault Relayer on mainnet (same address) | ## Resources * **[API Integration Guide](/cow-protocol/howto/integrate/api)** — Full API integration walkthrough * **[Quickstart: Raw API (cURL)](/cow-protocol/tutorials/quickstart-curl)** — End-to-end cURL walkthrough on Sepolia * **[Error Reference](/cow-protocol/reference/core/error-reference)** — All API error codes and fixes * **[Rate Limits](/cow-protocol/reference/core/rate-limits)** — Rate limits apply equally on testnet