Test a crypto buy and the fees inside the quote

Failure modes in this flow

The quote is where the disclosure happens, and every line of it feeds the amount of asset the customer ends up with.

The spread is the line worth asserting most carefully. It is a cost expressed as a price adjustment rather than a fee, and a quote that omits it while still charging it is the most common complaint against card crypto purchases.

Writing the objective

The invested figure is asserted as well as the two deductions, so a quote whose fees are individually correct but do not reconcile against the total fails.

---
mode: testing
url: https://my-testing-repo-main.vercel.app/coinbase-clone-app/buy?reset=true
max_steps: 45
tags: [coinbase, fintech, crypto]
---

# Coinbaze 18.1: Crypto buy

Catalog objective: buy a small amount of BTC with a test card.
Key assertion: the purchase is confirmed and the balance is credited.

## Set the order up
Select "BTC" in "Asset", type "100" into "Amount in USD", and make sure "One-time purchase" is selected.

## Verify the quote breakdown
Verify the Quote card shows "Amount" of "$100.00", "Card fee (1.49%)" of "$1.49", "Spread (0.5%)" of "$0.50", "Invested" of "$98.01" and "You receive" of "0.00152472 BTC".

## Pay with the test card
Type "4242 4242 4242 4242" into "Card number" and click the buy button.

## Verify the purchase and the credited balance
Verify a green banner titled "Purchase complete" says "0.00152472 BTC" was bought for $100.00, then go to https://my-testing-repo-main.vercel.app/coinbase-clone-app and verify the BTC holding has increased above its starting 0.00412 BTC.

The final step navigates to the account page and checks the holding increased above its starting value, which verifies the credit rather than trusting the purchase confirmation.

The assertions in detail

A quote, a payment, and an independent check of the balance.

Checking the holding on the account page rather than the confirmation is what proves the asset was actually credited rather than merely reported.

Running it locally

kane-cli testmd run tests/coinbase/crypto-buy_test.md

Prices move, so against a live environment capture the quoted quantity as a variable and assert the balance increased by that captured amount.

Fee disclosure is a regulated surface in a growing number of markets. Building a suite from requirements covers tying assertions to a source, and running in CI covers catching a change to them.