Implementation of MCP for LLM Observability capture to PostHig

src/utils/error.util.test.ts

@@ -0,0 +1,115 @@
+import {
+	McpError,
+	ErrorType,
+	createApiError,
+	createUnexpectedError,
+	getDeepOriginalError,
+	formatErrorForMcpTool,
+} from './error.util.js';
+
+describe('error.util', () => {
+	describe('getDeepOriginalError', () => {
+		it('should return the deepest original error in a chain', () => {
+			// Create a nested chain of errors
+			const deepestError = new Error('Root cause');
+			const middleError = createApiError(
+				'Middle error',
+				500,
+				deepestError,
+			);
+			const topError = createUnexpectedError('Top error', middleError);
+
+			// Should extract the deepest error
+			const result = getDeepOriginalError(topError);
+			expect(result).toBe(deepestError);
+		});
+
+		it('should handle null/undefined input', () => {
+			expect(getDeepOriginalError(null)).toBeNull();
+			expect(getDeepOriginalError(undefined)).toBeUndefined();
+		});
+
+		it('should return the input if it has no originalError', () => {
+			const error = new Error('Simple error');
+			expect(getDeepOriginalError(error)).toBe(error);
+		});
+
+		it('should handle non-Error objects', () => {
+			const nonError = { message: 'Not an error' };
+			expect(getDeepOriginalError(nonError)).toBe(nonError);
+		});
+
+		it('should prevent infinite recursion with circular references', () => {
+			const error1 = new McpError('Error 1', ErrorType.UNEXPECTED_ERROR);
+			const error2 = new McpError(
+				'Error 2',
+				ErrorType.UNEXPECTED_ERROR,
+				undefined,
+				error1,
+			);
+			// Create circular reference
+			error1.originalError = error2;
+
+			// Should not cause stack overflow, should return one of the errors
+			const result = getDeepOriginalError(error1);
+			expect(result).toBeTruthy();
+			expect(result instanceof Error).toBe(true);
+		});
+	});
+
+	describe('formatErrorForMcpTool', () => {
+		it('should format McpError with metadata', () => {
+			const error = createApiError('Test error', 404, {
+				detail: 'Not found',
+			});
+			const result = formatErrorForMcpTool(error);
+
+			// Check the content
+			expect(result.content).toEqual([
+				{
+					type: 'text',
+					text: 'Error: Test error',
+				},
+			]);
+
+			// Check the metadata
+			expect(result.metadata).toBeDefined();
+			expect(result.metadata?.errorType).toBe(ErrorType.API_ERROR);
+			expect(result.metadata?.statusCode).toBe(404);
+			expect(result.metadata?.errorDetails).toEqual({
+				detail: 'Not found',
+			});
+		});
+
+		it('should wrap non-McpError with metadata', () => {
+			const error = new Error('Regular error');
+			const result = formatErrorForMcpTool(error);
+
+			// Check content
+			expect(result.content[0].text).toBe('Error: Regular error');
+
+			// Check metadata
+			expect(result.metadata?.errorType).toBe(ErrorType.UNEXPECTED_ERROR);
+			expect(result.metadata?.errorDetails).toHaveProperty(
+				'message',
+				'Regular error',
+			);
+		});
+
+		it('should extract error message from non-Error objects', () => {
+			const result = formatErrorForMcpTool('String error');
+			expect(result.content[0].text).toBe('Error: String error');
+			expect(result.metadata?.errorType).toBe(ErrorType.UNEXPECTED_ERROR);
+		});
+
+		it('should extract deep original error details', () => {
+			const deepError = { code: 'DEEP_ERROR', message: 'Deep cause' };
+			const middleError = createApiError('Middle layer', 500, deepError);
+			const topError = createUnexpectedError('Top error', middleError);
+
+			const result = formatErrorForMcpTool(topError);
+
+			expect(result.metadata?.errorDetails).toEqual(deepError);
+		});
+	});
+});