Refactor: Move backend files to backend/ directory and split .gitignore

backend/tests/test_helpers.py

@@ -0,0 +1,77 @@
+import pytest
+from langchain_core.messages import HumanMessage, AIMessage
+from ea_chatbot.utils.helpers import merge_agent_state
+
+def test_merge_agent_state_list_accumulation():
+    """Verify that list fields (messages, plots) are accumulated (appended)."""
+    current_state = {
+        "messages": [HumanMessage(content="hello")],
+        "plots": ["plot1"]
+    }
+    update = {
+        "messages": [AIMessage(content="hi")],
+        "plots": ["plot2"]
+    }
+    
+    merged = merge_agent_state(current_state, update)
+    
+    assert len(merged["messages"]) == 2
+    assert merged["messages"][0].content == "hello"
+    assert merged["messages"][1].content == "hi"
+    
+    assert len(merged["plots"]) == 2
+    assert merged["plots"] == ["plot1", "plot2"]
+
+def test_merge_agent_state_dict_update():
+    """Verify that dictionary fields (dfs) are updated (shallow merge)."""
+    current_state = {
+        "dfs": {"df1": "data1"}
+    }
+    update = {
+        "dfs": {"df2": "data2"}
+    }
+    
+    merged = merge_agent_state(current_state, update)
+    
+    assert merged["dfs"] == {"df1": "data1", "df2": "data2"}
+    
+    # Verify overwrite within dict
+    update_overwrite = {
+        "dfs": {"df1": "new_data1"}
+    }
+    merged_overwrite = merge_agent_state(merged, update_overwrite)
+    assert merged_overwrite["dfs"] == {"df1": "new_data1", "df2": "data2"}
+
+def test_merge_agent_state_standard_overwrite():
+    """Verify that standard fields are overwritten."""
+    current_state = {
+        "question": "old question",
+        "next_action": "old action",
+        "plan": "old plan"
+    }
+    update = {
+        "question": "new question",
+        "next_action": "new action",
+        "plan": "new plan"
+    }
+    
+    merged = merge_agent_state(current_state, update)
+    
+    assert merged["question"] == "new question"
+    assert merged["next_action"] == "new action"
+    assert merged["plan"] == "new plan"
+
+def test_merge_agent_state_none_handling():
+    """Verify that None updates or missing keys in update don't break things."""
+    current_state = {
+        "question": "test",
+        "messages": ["msg1"]
+    }
+    
+    # Empty update
+    assert merge_agent_state(current_state, {}) == current_state
+    
+    # Update with None value for overwritable field
+    merged_none = merge_agent_state(current_state, {"question": None})
+    assert merged_none["question"] is None
+    assert merged_none["messages"] == ["msg1"]