Implement CoinGecko API Client with Cryptocurrency Data Retrieval

.gitignore

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+node_modules/
+dist/
+.env
+__pycache__/
+.DS_Store
+*.log
+coverage/
+.vitest/

package.json

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+{
+  "name": "coin-gekko-api",
+  "version": "1.0.0",
+  "description": "Coin Gekko API Implementation",
+  "main": "dist/index.js",
+  "scripts": {
+    "build": "tsc",
+    "test": "vitest",
+    "start": "node dist/index.js"
+  },
+  "keywords": ["gekko", "crypto", "api"],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "@types/node": "^16.0.0",
+    "typescript": "^4.5.0",
+    "vitest": "^0.30.0"
+  },
+  "dependencies": {
+    "axios": "^0.21.1"
+  }
+}

src/index.spec.ts

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+import { describe, it, expect } from 'vitest';
+import { CoinGekkoApi } from './index';
+import axios from 'axios';
+import MockAdapter from 'axios-mock-adapter';
+
+describe('CoinGekkoApi', () => {
+  const mock = new MockAdapter(axios);
+  const api = new CoinGekkoApi();
+
+  afterEach(() => {
+    mock.reset();
+  });
+
+  describe('getCoinList', () => {
+    it('should fetch coin list successfully', async () => {
+      const mockCoins = [
+        {
+          id: 'bitcoin',
+          symbol: 'btc',
+          name: 'Bitcoin',
+          current_price: 50000,
+          market_cap: 1000000000000
+        }
+      ];
+
+      mock.onGet(/coins\/markets/).reply(200, mockCoins);
+
+      const coins = await api.getCoinList(1);
+      expect(coins).toHaveLength(1);
+      expect(coins[0]).toEqual({
+        id: 'bitcoin',
+        symbol: 'btc',
+        name: 'Bitcoin',
+        price: 50000,
+        marketCap: 1000000000000
+      });
+    });
+
+    it('should handle error when fetching coin list fails', async () => {
+      mock.onGet(/coins\/markets/).reply(500);
+
+      await expect(api.getCoinList()).rejects.toThrow('Failed to fetch coin list');
+    });
+  });
+
+  describe('getCoinById', () => {
+    it('should fetch coin details successfully', async () => {
+      const mockCoin = {
+        id: 'bitcoin',
+        symbol: 'btc',
+        name: 'Bitcoin',
+        market_data: {
+          current_price: { usd: 50000 },
+          market_cap: { usd: 1000000000000 }
+        }
+      };
+
+      mock.onGet(/coins\/bitcoin/).reply(200, mockCoin);
+
+      const coin = await api.getCoinById('bitcoin');
+      expect(coin).toEqual({
+        id: 'bitcoin',
+        symbol: 'btc',
+        name: 'Bitcoin',
+        price: 50000,
+        marketCap: 1000000000000
+      });
+    });
+
+    it('should return null for non-existent coin', async () => {
+      mock.onGet(/coins\/nonexistent/).reply(404);
+
+      const coin = await api.getCoinById('nonexistent');
+      expect(coin).toBeNull();
+    });
+
+    it('should throw error for invalid coin id', async () => {
+      await expect(api.getCoinById('')).rejects.toThrow('Coin ID is required');
+    });
+  });
+});

src/index.ts

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+import axios from 'axios';
+
+export interface CoinData {
+  id: string;
+  symbol: string;
+  name: string;
+  price: number;
+  marketCap: number;
+}
+
+export class CoinGekkoApi {
+  private baseUrl: string;
+
+  constructor(baseUrl: string = 'https://api.coingecko.com/api/v3') {
+    this.baseUrl = baseUrl;
+  }
+
+  async getCoinList(limit: number = 100): Promise<CoinData[]> {
+    try {
+      const response = await axios.get(`${this.baseUrl}/coins/markets`, {
+        params: {
+          vs_currency: 'usd',
+          order: 'market_cap_desc',
+          per_page: limit,
+          page: 1,
+          sparkline: false
+        }
+      });
+
+      return response.data.map((coin: any) => ({
+        id: coin.id,
+        symbol: coin.symbol,
+        name: coin.name,
+        price: coin.current_price,
+        marketCap: coin.market_cap
+      }));
+    } catch (error) {
+      console.error('Error fetching coin list:', error);
+      throw new Error('Failed to fetch coin list');
+    }
+  }
+
+  async getCoinById(id: string): Promise<CoinData | null> {
+    if (!id) {
+      throw new Error('Coin ID is required');
+    }
+
+    try {
+      const response = await axios.get(`${this.baseUrl}/coins/${id}`);
+      const coin = response.data;
+
+      return {
+        id: coin.id,
+        symbol: coin.symbol,
+        name: coin.name,
+        price: coin.market_data.current_price.usd,
+        marketCap: coin.market_data.market_cap.usd
+      };
+    } catch (error) {
+      if (axios.isAxiosError(error) && error.response?.status === 404) {
+        return null;
+      }
+      console.error('Error fetching coin details:', error);
+      throw new Error('Failed to fetch coin details');
+    }
+  }
+}

tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es2020",
+    "module": "commonjs",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "outDir": "./dist",
+    "rootDir": "./src"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "**/*.spec.ts"]
+}