Start LangGraph backend migration foundation

test/core/test_config.py

@@ -0,0 +1,78 @@
+import pytest
+from pydantic import ValidationError
+
+from src.core.config import Settings
+
+
+def test_fastgpt_backend_accepts_legacy_environment_names():
+    settings = Settings(
+        _env_file=None,
+        ZNJJ_ENVIRONMENT="test",
+        AGENT_BACKEND="fastgpt",
+        ANALYSIS_AUTH_TOKEN="test-fastgpt-key",
+        ANALYSIS_SERVICE_URL="http://fastgpt.test",
+        APP_ID="test-app",
+    )
+
+    assert settings.environment == "test"
+    assert settings.agent_backend == "fastgpt"
+    assert settings.has_fastgpt_config
+    assert settings.fastgpt_api_key.get_secret_value() == "test-fastgpt-key"
+
+
+def test_fastgpt_backend_rejects_incomplete_configuration():
+    with pytest.raises(ValidationError, match="FastGPT backend requires"):
+        Settings(
+            _env_file=None,
+            environment="test",
+            agent_backend="fastgpt",
+            fastgpt_api_key="test-key",
+        )
+
+
+def test_langgraph_backend_requires_only_minimal_llm_configuration():
+    settings = Settings(
+        _env_file=None,
+        environment="test",
+        agent_backend="langgraph",
+        langgraph_checkpointer="memory",
+        llm_api_key="test-llm-key",
+        llm_model="test-model",
+    )
+
+    assert settings.agent_backend == "langgraph"
+    assert settings.langgraph_checkpointer == "memory"
+    assert not settings.has_fastgpt_config
+
+
+def test_langgraph_backend_rejects_missing_llm_configuration():
+    with pytest.raises(ValidationError, match="LLM_API_KEY, LLM_MODEL"):
+        Settings(
+            _env_file=None,
+            environment="test",
+            agent_backend="langgraph",
+        )
+
+
+def test_production_cannot_use_memory_checkpointer():
+    with pytest.raises(ValidationError, match="cannot use the memory checkpointer"):
+        Settings(
+            _env_file=None,
+            environment="production",
+            agent_backend="langgraph",
+            langgraph_checkpointer="memory",
+            llm_api_key="test-llm-key",
+            llm_model="test-model",
+        )
+
+
+def test_secret_values_are_masked_in_settings_repr():
+    settings = Settings(
+        _env_file=None,
+        environment="test",
+        agent_backend="langgraph",
+        llm_api_key="never-print-this-key",
+        llm_model="test-model",
+    )
+
+    assert "never-print-this-key" not in repr(settings)