test(frontend): add tests for BtcSendReview components (#3748)

# Motivation

As agreed, before implementing updates to a component, covering it with
unit tests first. In this case, it's about BtcSendReview component. In
the next PRs, I will be adding an additional check for the
"insufficient-fund-for-fee" error.

src/frontend/src/tests/btc/components/send/BtcSendReview.spec.ts

@@ -0,0 +1,153 @@
+import BtcSendReview from '$btc/components/send/BtcSendReview.svelte';
+import * as btcPendingSendTransactionsStatusStore from '$btc/derived/btc-pending-sent-transactions-status.derived';
+import { BTC_MAINNET_TOKEN } from '$env/tokens/tokens.btc.env';
+import { REVIEW_FORM_SEND_BUTTON } from '$lib/constants/test-ids.constants';
+import { SEND_CONTEXT_KEY } from '$lib/stores/send.store';
+import { mockBtcAddress, mockUtxosFee } from '$tests/mocks/btc.mock';
+import en from '$tests/mocks/i18n.mock';
+import { mockPage } from '$tests/mocks/page.store.mock';
+import { render, waitFor } from '@testing-library/svelte';
+import { readable } from 'svelte/store';
+
+describe('BtcSendReview', () => {
+	const mockContext = (balance: bigint | undefined = 1000000n) =>
+		new Map([
+			[
+				SEND_CONTEXT_KEY,
+				{
+					sendToken: readable(BTC_MAINNET_TOKEN),
+					sendTokenDecimals: readable(BTC_MAINNET_TOKEN.decimals),
+					sendTokenId: readable(BTC_MAINNET_TOKEN.id),
+					sendTokenStandard: readable(BTC_MAINNET_TOKEN.standard),
+					sendTokenSymbol: readable(BTC_MAINNET_TOKEN.symbol),
+					sendBalance: readable(balance)
+				}
+			]
+		]);
+	const props = {
+		destination: mockBtcAddress,
+		source: mockBtcAddress,
+		amount: 0.0001,
+		networkId: BTC_MAINNET_TOKEN.network.id,
+		utxosFee: mockUtxosFee
+	};
+	const mockBtcPendingSendTransactionsStatusStore = (
+		status:
+			| btcPendingSendTransactionsStatusStore.BtcPendingSentTransactionsStatus
+			| undefined = btcPendingSendTransactionsStatusStore.BtcPendingSentTransactionsStatus.NONE
+	) =>
+		vi
+			.spyOn(btcPendingSendTransactionsStatusStore, 'initPendingSentTransactionsStatus')
+			.mockImplementation(() => readable(status));
+
+	const buttonTestId = REVIEW_FORM_SEND_BUTTON;
+
+	beforeEach(() => {
+		mockPage.reset();
+	});
+
+	it('should enable the next button if all requirements are met', () => {
+		mockBtcPendingSendTransactionsStatusStore();
+
+		const { getByTestId } = render(BtcSendReview, {
+			props: {
+				...props,
+				utxosFee: mockUtxosFee
+			},
+			context: mockContext()
+		});
+
+		expect(getByTestId(buttonTestId)).not.toHaveAttribute('disabled');
+	});
+
+	it('should disable the next button if amount is undefined', () => {
+		mockBtcPendingSendTransactionsStatusStore();
+
+		const { getByTestId } = render(BtcSendReview, {
+			props: {
+				...props,
+				amount: undefined
+			},
+			context: mockContext()
+		});
+
+		expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+	});
+
+	it('should disable the next button if amount is invalid', () => {
+		mockBtcPendingSendTransactionsStatusStore();
+
+		const { getByTestId } = render(BtcSendReview, {
+			props: {
+				...props,
+				amount: -1
+			},
+			context: mockContext()
+		});
+
+		expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+	});
+
+	it('should disable the next button if utxos are undefined', () => {
+		mockBtcPendingSendTransactionsStatusStore();
+
+		const { getByTestId } = render(BtcSendReview, {
+			props: {
+				...props,
+				utxosFee: undefined
+			},
+			context: mockContext()
+		});
+
+		expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+	});
+
+	it('should disable the next button if utxos are not available', () => {
+		mockBtcPendingSendTransactionsStatusStore();
+
+		const { getByTestId } = render(BtcSendReview, {
+			props: {
+				...props,
+				utxosFee: {
+					...mockUtxosFee,
+					utxos: []
+				}
+			},
+			context: mockContext()
+		});
+
+		expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+	});
+
+	it('should render btc send warning message and keep button disabled if there some pending txs', async () => {
+		mockBtcPendingSendTransactionsStatusStore(
+			btcPendingSendTransactionsStatusStore.BtcPendingSentTransactionsStatus.SOME
+		);
+
+		const { container, getByTestId } = render(BtcSendReview, {
+			props,
+			context: mockContext()
+		});
+
+		await waitFor(() => {
+			expect(container).toHaveTextContent(en.send.info.pending_bitcoin_transaction);
+
+			expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+		});
+	});
+
+	it('should disable the next button if pending txs have not been loaded yet', async () => {
+		mockBtcPendingSendTransactionsStatusStore(
+			btcPendingSendTransactionsStatusStore.BtcPendingSentTransactionsStatus.LOADING
+		);
+
+		const { getByTestId } = render(BtcSendReview, {
+			props,
+			context: mockContext()
+		});
+
+		await waitFor(() => {
+			expect(getByTestId(buttonTestId)).toHaveAttribute('disabled');
+		});
+	});
+});