test(sdk): add error branch coverage tests

Add tests for error handling and method variations:
- 401/403 errors with no retry behavior
- 404 error handling
- sendApi with POST/PUT/PATCH methods and empty body

These tests validate error handling paths and HTTP method variations
to improve branch coverage.

Author: jdalton

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

@@ -0,0 +1,124 @@
+/** @fileoverview Tests for uncovered error branches in Socket SDK. */
+
+import { describe, expect, it } from 'vitest'
+
+import { SocketSdk } from '../../src/index'
+import {
+  createRouteHandler,
+  jsonResponse,
+  setupLocalHttpServer,
+} from '../utils/local-server-helpers.mts'
+
+import type { SocketSdkGenericResult } from '../../src/types'
+import type { IncomingMessage } from 'node:http'
+
+describe('SocketSdk - Error Branch Coverage', () => {
+  describe('401/403 errors (no retry)', () => {
+    const getBaseUrl = setupLocalHttpServer(
+      createRouteHandler({
+        '/401-test': jsonResponse(401, { error: 'Unauthorized' }),
+        '/403-test': jsonResponse(403, { error: 'Forbidden' }),
+      }),
+    )
+
+    const getClient = () =>
+      new SocketSdk('test-token', { baseUrl: getBaseUrl(), retries: 3 })
+
+    it('should not retry 401 errors', async () => {
+      const result = (await getClient().getApi('/401-test', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(401)
+        expect(result.cause).toContain('Authentication failed')
+      }
+    })
+
+    it('should not retry 403 errors', async () => {
+      const result = (await getClient().getApi('/403-test', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(403)
+        expect(result.cause).toContain('Authorization failed')
+      }
+    })
+  })
+
+  describe('404 errors', () => {
+    const getBaseUrl = setupLocalHttpServer(
+      createRouteHandler({
+        '/404-test': jsonResponse(404, { error: 'Not Found' }),
+      }),
+    )
+
+    const getClient = () =>
+      new SocketSdk('test-token', { baseUrl: getBaseUrl(), retries: 0 })
+
+    it('should handle 404 errors', async () => {
+      const result = (await getClient().getApi('/404-test', {
+        throws: false,
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(false)
+      if (!result.success) {
+        expect(result.status).toBe(404)
+        expect(result.cause).toContain('Resource not found')
+      }
+    })
+  })
+
+  describe('sendApi with different methods', () => {
+    const getBaseUrl = setupLocalHttpServer(
+      createRouteHandler({
+        '/test-endpoint': (_req: IncomingMessage, res) => {
+          res.writeHead(200, { 'Content-Type': 'application/json' })
+          res.end(JSON.stringify({ success: true, data: { id: 123 } }))
+        },
+      }),
+    )
+
+    const getClient = () =>
+      new SocketSdk('test-token', { baseUrl: getBaseUrl(), retries: 0 })
+
+    it('should handle sendApi with POST method', async () => {
+      const result = await getClient().sendApi('/test-endpoint', {
+        body: { test: 'data' },
+        method: 'POST',
+      })
+
+      expect(result.success).toBe(true)
+    })
+
+    it('should handle sendApi with PUT method', async () => {
+      const result = await getClient().sendApi('/test-endpoint', {
+        body: { test: 'data' },
+        method: 'PUT',
+      })
+
+      expect(result.success).toBe(true)
+    })
+
+    it('should handle sendApi with empty body', async () => {
+      const result = await getClient().sendApi('/test-endpoint', {
+        body: {},
+        method: 'POST',
+      })
+
+      expect(result.success).toBe(true)
+    })
+
+    it('should handle sendApi with null in body', async () => {
+      const result = (await getClient().sendApi('/test-endpoint', {
+        body: { value: null },
+        method: 'POST',
+      })) as SocketSdkGenericResult<unknown>
+
+      expect(result.success).toBe(true)
+    })
+  })
+})