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/**
* Exercise 2: Build a JSON Parser Runnable
*
* Goal: Create a Runnable that parses JSON strings safely
*
* Requirements:
* - Takes a JSON string as input
* - Parses it to an object
* - Handles errors gracefully (return null if invalid)
* - Optional: Add a default value option
*
* Example:
* const parser = new JsonParserRunnable();
* await parser.invoke('{"name":"Alice"}'); // Should return { name: "Alice" }
* await parser.invoke('invalid json'); // Should return null
*/
import { Runnable } from '../../../../src/index.js';
/**
* JsonParserRunnable - Safely parses JSON strings
*
* TODO: Implement this class
*/
class JsonParserRunnable extends Runnable {
constructor(options = {}) {
// TODO: Call super()
// TODO: Store options (like defaultValue)
}
async _call(input, config) {
// TODO: Check if input is a string
// TODO: Try to parse the JSON
// TODO: If parsing fails, return null or defaultValue
// TODO: Return the parsed object
}
}
// ============================================================================
// Tests
// ============================================================================
async function runTests() {
console.log('🧪 Testing JsonParserRunnable...\n');
try {
// Test 1: Valid JSON object
console.log('Test 1: Valid JSON object');
const parser = new JsonParserRunnable();
const result1 = await parser.invoke('{"name":"Alice","age":30}');
console.assert(result1.name === 'Alice', 'Should parse name');
console.assert(result1.age === 30, 'Should parse age');
console.log('✅ Parsed: {"name":"Alice","age":30}\n');
// Test 2: Valid JSON array
console.log('Test 2: Valid JSON array');
const result2 = await parser.invoke('[1, 2, 3, 4, 5]');
console.assert(Array.isArray(result2), 'Should return array');
console.assert(result2.length === 5, 'Should have 5 elements');
console.log('✅ Parsed: [1, 2, 3, 4, 5]\n');
// Test 3: Invalid JSON returns null
console.log('Test 3: Invalid JSON returns null');
const result3 = await parser.invoke('this is not json');
console.assert(result3 === null, 'Should return null for invalid JSON');
console.log('✅ Returns null for invalid JSON\n');
// Test 4: Empty string returns null
console.log('Test 4: Empty string returns null');
const result4 = await parser.invoke('');
console.assert(result4 === null, 'Should return null for empty string');
console.log('✅ Returns null for empty string\n');
// Test 5: With default value
console.log('Test 5: With default value');
const parserWithDefault = new JsonParserRunnable({
defaultValue: { error: 'Invalid JSON' }
});
const result5 = await parserWithDefault.invoke('bad json');
console.assert(result5.error === 'Invalid JSON', 'Should return default value');
console.log('✅ Returns default value for invalid JSON\n');
// Test 6: Nested JSON
console.log('Test 6: Nested JSON');
const nested = '{"user":{"name":"Bob","address":{"city":"NYC"}}}';
const result6 = await parser.invoke(nested);
console.assert(result6.user.address.city === 'NYC', 'Should parse nested objects');
console.log('✅ Parsed nested JSON\n');
console.log('🎉 All tests passed!');
} catch (error) {
console.error('❌ Test failed:', error.message);
console.error(error.stack);
}
}
// Run tests
if (import.meta.url === `file://${process.argv[1]}`) {
runTests();
}
export { JsonParserRunnable }; |