test: add error details parsing and HTTP 413 tests

Add tests for API error response parsing:
- String error details extraction (lines 480, 483)
- Object error details serialization
- 413 Payload Too Large error handling (line 547)

Improves coverage of error message construction in #handleApiError

Author: jdalton

test/unit/socket-sdk-error-details.test.mts

@@ -0,0 +1,98 @@
+/** @fileoverview Tests for error details parsing and specific HTTP error codes. */
+
+import { describe, expect, it } from 'vitest'
+
+import { SocketSdk } from '../../src/index'
+import {
+  createRouteHandler,
+  setupLocalHttpServer,
+} from '../utils/local-server-helpers.mts'
+
+import type { SocketSdkGenericResult } from '../../src/types'
+import type { IncomingMessage } from 'node:http'
+
+describe('SocketSdk - Error Details and HTTP Codes', () => {
+  describe('Error details parsing', () => {
+    const getBaseUrl = setupLocalHttpServer(
+      createRouteHandler({
+        '/error-with-string-details': (_req: IncomingMessage, res) => {
+          res.writeHead(400, { 'Content-Type': 'application/json' })
+          res.end(
+            JSON.stringify({
+              error: {
+                message: 'Validation failed',
+                details: 'Package name is required',
+              },
+            }),
+          )
+        },
+        '/error-with-object-details': (_req: IncomingMessage, res) => {
+          res.writeHead(400, { 'Content-Type': 'application/json' })
+          res.end(
+            JSON.stringify({
+              error: {
+                message: 'Validation failed',
+                details: { field: 'packageName', reason: 'required' },
+              },
+            }),
+          )
+        },
+      }),
+    )
+
+    const getClient = () =>
+      new SocketSdk('test-token', { baseUrl: getBaseUrl(), retries: 0 })
+
+    it('should parse string error details', async () => {
+      const result = (await getClient().getApi('/error-with-string-details', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(400)
+        expect(result.cause).toContain('Details: Package name is required')
+      }
+    })
+
+    it('should parse object error details', async () => {
+      const result = (await getClient().getApi('/error-with-object-details', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(400)
+        expect(result.cause).toContain('Details:')
+        expect(result.cause).toContain('packageName')
+      }
+    })
+  })
+
+  describe('413 Payload Too Large', () => {
+    const getBaseUrl = setupLocalHttpServer(
+      createRouteHandler({
+        '/too-large': (_req: IncomingMessage, res) => {
+          res.writeHead(413, { 'Content-Type': 'application/json' })
+          res.end(JSON.stringify({ error: { message: 'Payload too large' } }))
+        },
+      }),
+    )
+
+    const getClient = () =>
+      new SocketSdk('test-token', { baseUrl: getBaseUrl(), retries: 0 })
+
+    it('should handle 413 Payload Too Large error', async () => {
+      const result = (await getClient().getApi('/too-large', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(413)
+        expect(result.cause).toContain('Payload too large')
+        expect(result.cause).toContain('Reduce the number')
+      }
+    })
+  })
+})