feat: add get_server_config function with validation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_config.py

@@ -5,7 +5,7 @@ import tempfile
 import pytest
 from pathlib import Path
 
-from zzpyjenkins.config import load_config, ConfigError
+from zzpyjenkins.config import load_config, ConfigError, get_server_config
 
 
 def test_load_config_file_not_found():
@@ -27,3 +27,44 @@ def test_load_config_invalid_toml():
         assert "Invalid TOML syntax" in str(exc_info.value)
     finally:
         temp_path.unlink()
+
+
+def test_get_server_config_success():
+    """Test getting a valid server config."""
+    config = {
+        "work": {
+            "url": "https://jenkins.example.com",
+            "username": "user",
+            "password": "pass"
+        }
+    }
+    result = get_server_config(config, "work")
+    assert result == ("https://jenkins.example.com", "user", "pass")
+
+
+def test_get_server_config_not_found():
+    """Test error when server name doesn't exist."""
+    config = {
+        "work": {
+            "url": "https://jenkins.example.com",
+            "username": "user",
+            "password": "pass"
+        }
+    }
+    with pytest.raises(ConfigError) as exc_info:
+        get_server_config(config, "home")
+    assert "Server 'home' not found" in str(exc_info.value)
+    assert "work" in str(exc_info.value)
+
+
+def test_get_server_config_missing_field():
+    """Test error when required field is missing."""
+    config = {
+        "incomplete": {
+            "url": "https://jenkins.example.com",
+            "username": "user"
+        }
+    }
+    with pytest.raises(ConfigError) as exc_info:
+        get_server_config(config, "incomplete")
+    assert "password" in str(exc_info.value)