diff --git a/tests/test_alpha_vantage_integration.py b/tests/test_alpha_vantage_integration.py
new file mode 100644
index 00000000..327376a9
--- /dev/null
+++ b/tests/test_alpha_vantage_integration.py
@@ -0,0 +1,518 @@
+"""Integration tests for the Alpha Vantage data layer.
+
+All HTTP requests are mocked so these tests run offline and without API-key or
+rate-limit concerns.  The mocks reproduce realistic Alpha Vantage response shapes
+so that the code-under-test exercises every significant branch.
+"""
+
+import json
+import pytest
+from unittest.mock import patch, MagicMock
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+CSV_DAILY_ADJUSTED = (
+    "timestamp,open,high,low,close,adjusted_close,volume,dividend_amount,split_coefficient\n"
+    "2024-01-05,185.00,187.50,184.20,186.00,186.00,50000000,0.0000,1.0\n"
+    "2024-01-04,183.00,186.00,182.50,185.00,185.00,45000000,0.0000,1.0\n"
+    "2024-01-03,181.00,184.00,180.00,183.00,183.00,48000000,0.0000,1.0\n"
+)
+
+RATE_LIMIT_JSON = json.dumps({
+    "Information": (
+        "Thank you for using Alpha Vantage! Our standard API rate limit is 25 requests "
+        "per day. Please subscribe to any of the premium plans at "
+        "https://www.alphavantage.co/premium/ to instantly remove all daily rate limits."
+    )
+})
+
+INVALID_KEY_JSON = json.dumps({
+    "Information": "Invalid API key. Please claim your free API key at https://www.alphavantage.co/support/"
+})
+
+CSV_SMA = (
+    "time,SMA\n"
+    "2024-01-05,182.50\n"
+    "2024-01-04,181.00\n"
+    "2024-01-03,179.50\n"
+)
+
+CSV_RSI = (
+    "time,RSI\n"
+    "2024-01-05,55.30\n"
+    "2024-01-04,53.10\n"
+    "2024-01-03,51.90\n"
+)
+
+OVERVIEW_JSON = json.dumps({
+    "Symbol": "AAPL",
+    "Name": "Apple Inc",
+    "Sector": "TECHNOLOGY",
+    "MarketCapitalization": "3000000000000",
+    "PERatio": "30.5",
+    "Beta": "1.2",
+})
+
+
+def _mock_response(text: str, status_code: int = 200):
+    """Return a mock requests.Response with the given text body."""
+    resp = MagicMock()
+    resp.status_code = status_code
+    resp.text = text
+    resp.raise_for_status = MagicMock()
+    return resp
+
+
+# ---------------------------------------------------------------------------
+# AlphaVantageRateLimitError
+# ---------------------------------------------------------------------------
+
+class TestAlphaVantageRateLimitError:
+    """Tests for the custom AlphaVantageRateLimitError exception class."""
+
+    def test_is_exception_subclass(self):
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        assert issubclass(AlphaVantageRateLimitError, Exception)
+
+    def test_can_be_raised_and_caught(self):
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        with pytest.raises(AlphaVantageRateLimitError, match="rate limit"):
+            raise AlphaVantageRateLimitError("rate limit exceeded")
+
+
+# ---------------------------------------------------------------------------
+# _make_api_request
+# ---------------------------------------------------------------------------
+
+class TestMakeApiRequest:
+    """Tests for the internal _make_api_request helper."""
+
+    def test_returns_csv_text_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_common import _make_api_request
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(CSV_DAILY_ADJUSTED)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = _make_api_request("TIME_SERIES_DAILY_ADJUSTED",
+                                           {"symbol": "AAPL", "datatype": "csv"})
+
+        assert "timestamp" in result
+        assert "186.00" in result
+
+    def test_raises_rate_limit_error_on_information_field(self):
+        from tradingagents.dataflows.alpha_vantage_common import (
+            _make_api_request,
+            AlphaVantageRateLimitError,
+        )
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    _make_api_request("TIME_SERIES_DAILY_ADJUSTED", {"symbol": "AAPL"})
+
+    def test_raises_rate_limit_error_for_invalid_api_key(self):
+        from tradingagents.dataflows.alpha_vantage_common import (
+            _make_api_request,
+            AlphaVantageRateLimitError,
+        )
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(INVALID_KEY_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "invalid_key"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    _make_api_request("OVERVIEW", {"symbol": "AAPL"})
+
+    def test_missing_api_key_raises_value_error(self):
+        from tradingagents.dataflows.alpha_vantage_common import _make_api_request
+        import os
+
+        env = {k: v for k, v in os.environ.items() if k != "ALPHA_VANTAGE_API_KEY"}
+        with patch.dict("os.environ", env, clear=True):
+            with pytest.raises(ValueError, match="ALPHA_VANTAGE_API_KEY"):
+                _make_api_request("OVERVIEW", {"symbol": "AAPL"})
+
+    def test_network_timeout_propagates(self):
+        from tradingagents.dataflows.alpha_vantage_common import _make_api_request
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   side_effect=TimeoutError("connection timed out")):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(TimeoutError):
+                    _make_api_request("OVERVIEW", {"symbol": "AAPL"})
+
+    def test_http_error_propagates_via_raise_for_status(self):
+        """HTTP 4xx/5xx raises an exception via response.raise_for_status()."""
+        import requests as _requests
+        from tradingagents.dataflows.alpha_vantage_common import _make_api_request
+
+        bad_resp = _mock_response("", status_code=403)
+        bad_resp.raise_for_status.side_effect = _requests.HTTPError("403 Forbidden")
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=bad_resp):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(_requests.HTTPError):
+                    _make_api_request("OVERVIEW", {"symbol": "AAPL"})
+
+
+# ---------------------------------------------------------------------------
+# _filter_csv_by_date_range
+# ---------------------------------------------------------------------------
+
+class TestFilterCsvByDateRange:
+    """Tests for the _filter_csv_by_date_range helper."""
+
+    def test_filters_rows_to_date_range(self):
+        from tradingagents.dataflows.alpha_vantage_common import _filter_csv_by_date_range
+
+        result = _filter_csv_by_date_range(CSV_DAILY_ADJUSTED, "2024-01-04", "2024-01-05")
+
+        assert "2024-01-03" not in result
+        assert "2024-01-04" in result
+        assert "2024-01-05" in result
+
+    def test_empty_input_returns_empty(self):
+        from tradingagents.dataflows.alpha_vantage_common import _filter_csv_by_date_range
+
+        assert _filter_csv_by_date_range("", "2024-01-01", "2024-01-31") == ""
+
+    def test_whitespace_only_input_returns_as_is(self):
+        from tradingagents.dataflows.alpha_vantage_common import _filter_csv_by_date_range
+
+        result = _filter_csv_by_date_range("   ", "2024-01-01", "2024-01-31")
+        assert result.strip() == ""
+
+    def test_all_rows_outside_range_returns_header_only(self):
+        from tradingagents.dataflows.alpha_vantage_common import _filter_csv_by_date_range
+
+        result = _filter_csv_by_date_range(CSV_DAILY_ADJUSTED, "2023-01-01", "2023-12-31")
+        lines = [l for l in result.strip().split("\n") if l]
+        # Only header row should remain
+        assert len(lines) == 1
+        assert "timestamp" in lines[0]
+
+
+# ---------------------------------------------------------------------------
+# format_datetime_for_api
+# ---------------------------------------------------------------------------
+
+class TestFormatDatetimeForApi:
+    """Tests for format_datetime_for_api."""
+
+    def test_yyyy_mm_dd_is_converted(self):
+        from tradingagents.dataflows.alpha_vantage_common import format_datetime_for_api
+
+        result = format_datetime_for_api("2024-01-15")
+        assert result == "20240115T0000"
+
+    def test_already_formatted_string_is_returned_as_is(self):
+        from tradingagents.dataflows.alpha_vantage_common import format_datetime_for_api
+
+        result = format_datetime_for_api("20240115T1430")
+        assert result == "20240115T1430"
+
+    def test_datetime_object_is_converted(self):
+        from tradingagents.dataflows.alpha_vantage_common import format_datetime_for_api
+        from datetime import datetime
+
+        dt = datetime(2024, 1, 15, 14, 30)
+        result = format_datetime_for_api(dt)
+        assert result == "20240115T1430"
+
+    def test_unsupported_string_format_raises_value_error(self):
+        from tradingagents.dataflows.alpha_vantage_common import format_datetime_for_api
+
+        with pytest.raises(ValueError):
+            format_datetime_for_api("15-01-2024")
+
+    def test_unsupported_type_raises_value_error(self):
+        from tradingagents.dataflows.alpha_vantage_common import format_datetime_for_api
+
+        with pytest.raises(ValueError):
+            format_datetime_for_api(20240115)
+
+
+# ---------------------------------------------------------------------------
+# get_stock (alpha_vantage_stock)
+# ---------------------------------------------------------------------------
+
+class TestAlphaVantageGetStock:
+    """Tests for the Alpha Vantage get_stock function."""
+
+    def test_returns_csv_for_recent_date_range(self):
+        """Recent dates → compact outputsize; CSV data is filtered to range."""
+        from tradingagents.dataflows.alpha_vantage_stock import get_stock
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(CSV_DAILY_ADJUSTED)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_stock("AAPL", "2024-01-01", "2024-01-05")
+
+        assert isinstance(result, str)
+
+    def test_uses_full_outputsize_for_old_start_date(self):
+        """Old start date (>100 days ago) → outputsize=full is selected."""
+        from tradingagents.dataflows.alpha_vantage_stock import get_stock
+
+        captured_params = {}
+
+        def capture_request(url, params):
+            captured_params.update(params)
+            return _mock_response(CSV_DAILY_ADJUSTED)
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   side_effect=capture_request):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                get_stock("AAPL", "2020-01-01", "2020-01-05")
+
+        assert captured_params.get("outputsize") == "full"
+
+    def test_rate_limit_error_propagates(self):
+        from tradingagents.dataflows.alpha_vantage_stock import get_stock
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    get_stock("AAPL", "2024-01-01", "2024-01-05")
+
+
+# ---------------------------------------------------------------------------
+# get_fundamentals / get_balance_sheet / get_cashflow / get_income_statement
+# (alpha_vantage_fundamentals)
+# ---------------------------------------------------------------------------
+
+class TestAlphaVantageGetFundamentals:
+    """Tests for Alpha Vantage get_fundamentals."""
+
+    def test_returns_json_string_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_fundamentals
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(OVERVIEW_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_fundamentals("AAPL")
+
+        assert "Apple Inc" in result
+        assert "TECHNOLOGY" in result
+
+    def test_rate_limit_error_propagates(self):
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_fundamentals
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    get_fundamentals("AAPL")
+
+
+class TestAlphaVantageGetBalanceSheet:
+    def test_returns_response_text_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_balance_sheet
+
+        payload = json.dumps({"symbol": "AAPL", "annualReports": [], "quarterlyReports": []})
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(payload)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_balance_sheet("AAPL")
+
+        assert "AAPL" in result
+
+
+class TestAlphaVantageGetCashflow:
+    def test_returns_response_text_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_cashflow
+
+        payload = json.dumps({"symbol": "AAPL", "annualReports": [], "quarterlyReports": []})
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(payload)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_cashflow("AAPL")
+
+        assert "AAPL" in result
+
+
+class TestAlphaVantageGetIncomeStatement:
+    def test_returns_response_text_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_income_statement
+
+        payload = json.dumps({"symbol": "AAPL", "annualReports": [], "quarterlyReports": []})
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(payload)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_income_statement("AAPL")
+
+        assert "AAPL" in result
+
+
+# ---------------------------------------------------------------------------
+# get_news / get_global_news / get_insider_transactions (alpha_vantage_news)
+# ---------------------------------------------------------------------------
+
+NEWS_JSON = json.dumps({
+    "feed": [
+        {
+            "title": "Apple Hits Record High",
+            "url": "https://example.com/news/1",
+            "time_published": "20240105T150000",
+            "authors": ["John Doe"],
+            "summary": "Apple stock reached a new record.",
+            "overall_sentiment_label": "Bullish",
+        }
+    ]
+})
+
+INSIDER_JSON = json.dumps({
+    "data": [
+        {
+            "executive": "Tim Cook",
+            "transactionDate": "2024-01-15",
+            "transactionType": "Sale",
+            "sharesTraded": "10000",
+            "sharePrice": "150.00",
+        }
+    ]
+})
+
+
+class TestAlphaVantageGetNews:
+    def test_returns_news_response_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_news import get_news
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(NEWS_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_news("AAPL", "2024-01-01", "2024-01-05")
+
+        assert "Apple Hits Record High" in result
+
+    def test_rate_limit_error_propagates(self):
+        from tradingagents.dataflows.alpha_vantage_news import get_news
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    get_news("AAPL", "2024-01-01", "2024-01-05")
+
+
+class TestAlphaVantageGetGlobalNews:
+    def test_returns_global_news_response_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_news import get_global_news
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(NEWS_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_global_news("2024-01-15", look_back_days=7)
+
+        assert isinstance(result, str)
+
+    def test_look_back_days_affects_time_from_param(self):
+        """The time_from parameter should reflect the look_back_days offset."""
+        from tradingagents.dataflows.alpha_vantage_news import get_global_news
+
+        captured_params = {}
+
+        def capture(url, params):
+            captured_params.update(params)
+            return _mock_response(NEWS_JSON)
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   side_effect=capture):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                get_global_news("2024-01-15", look_back_days=7)
+
+        # time_from should be 7 days before 2024-01-15 → 2024-01-08
+        assert "20240108T0000" in captured_params.get("time_from", "")
+
+
+class TestAlphaVantageGetInsiderTransactions:
+    def test_returns_insider_data_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_news import get_insider_transactions
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(INSIDER_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_insider_transactions("AAPL")
+
+        assert "Tim Cook" in result
+
+    def test_rate_limit_error_propagates(self):
+        from tradingagents.dataflows.alpha_vantage_news import get_insider_transactions
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    get_insider_transactions("AAPL")
+
+
+# ---------------------------------------------------------------------------
+# get_indicator (alpha_vantage_indicator)
+# ---------------------------------------------------------------------------
+
+class TestAlphaVantageGetIndicator:
+    """Tests for the Alpha Vantage get_indicator function."""
+
+    def test_rsi_returns_formatted_string_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_indicator import get_indicator
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(CSV_RSI)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_indicator(
+                    "AAPL", "rsi", "2024-01-05", look_back_days=5
+                )
+
+        assert isinstance(result, str)
+        assert "RSI" in result.upper()
+
+    def test_sma_50_returns_formatted_string_on_success(self):
+        from tradingagents.dataflows.alpha_vantage_indicator import get_indicator
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(CSV_SMA)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_indicator(
+                    "AAPL", "close_50_sma", "2024-01-05", look_back_days=5
+                )
+
+        assert isinstance(result, str)
+        assert "SMA" in result.upper()
+
+    def test_unsupported_indicator_raises_value_error(self):
+        from tradingagents.dataflows.alpha_vantage_indicator import get_indicator
+
+        with pytest.raises(ValueError, match="not supported"):
+            get_indicator("AAPL", "unsupported_indicator", "2024-01-05", look_back_days=5)
+
+    def test_rate_limit_error_surfaces_as_error_string(self):
+        """Rate limit errors during indicator fetch result in an error string (not a raise)."""
+        from tradingagents.dataflows.alpha_vantage_indicator import get_indicator
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_response(RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_indicator("AAPL", "rsi", "2024-01-05", look_back_days=5)
+
+        assert "Error" in result or "rate limit" in result.lower()
+
+    def test_vwma_returns_informational_message(self):
+        """VWMA is not directly available; a descriptive message is returned."""
+        from tradingagents.dataflows.alpha_vantage_indicator import get_indicator
+
+        with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+            result = get_indicator("AAPL", "vwma", "2024-01-05", look_back_days=5)
+
+        assert "VWMA" in result
+        assert "not directly available" in result.lower() or "Volume Weighted" in result
diff --git a/tests/test_e2e_api_integration.py b/tests/test_e2e_api_integration.py
new file mode 100644
index 00000000..51fef3c9
--- /dev/null
+++ b/tests/test_e2e_api_integration.py
@@ -0,0 +1,378 @@
+"""End-to-end integration tests combining the Y Finance and Alpha Vantage data layers.
+
+These tests validate the full pipeline from the vendor-routing layer
+(interface.route_to_vendor) through data retrieval to formatted output, using
+mocks so that no real network calls are made.
+"""
+
+import json
+import pytest
+import pandas as pd
+from unittest.mock import patch, MagicMock, PropertyMock
+
+
+# ---------------------------------------------------------------------------
+# Shared mock data
+# ---------------------------------------------------------------------------
+
+_OHLCV_CSV_AV = (
+    "timestamp,open,high,low,close,adjusted_close,volume,dividend_amount,split_coefficient\n"
+    "2024-01-05,185.00,187.50,184.20,186.00,186.00,50000000,0.0000,1.0\n"
+    "2024-01-04,183.00,186.00,182.50,185.00,185.00,45000000,0.0000,1.0\n"
+)
+
+_OVERVIEW_JSON = json.dumps({
+    "Symbol": "AAPL",
+    "Name": "Apple Inc",
+    "Sector": "TECHNOLOGY",
+    "MarketCapitalization": "3000000000000",
+    "PERatio": "30.5",
+})
+
+_NEWS_JSON = json.dumps({
+    "feed": [
+        {
+            "title": "Apple Hits Record High",
+            "url": "https://example.com/news/1",
+            "time_published": "20240105T150000",
+            "summary": "Apple stock reached a new record.",
+            "overall_sentiment_label": "Bullish",
+        }
+    ]
+})
+
+_RATE_LIMIT_JSON = json.dumps({
+    "Information": (
+        "Thank you for using Alpha Vantage! Our standard API rate limit is 25 requests per day."
+    )
+})
+
+
+def _mock_av_response(text: str):
+    resp = MagicMock()
+    resp.text = text
+    resp.raise_for_status = MagicMock()
+    return resp
+
+
+def _make_yf_ohlcv_df():
+    idx = pd.date_range("2024-01-04", periods=2, freq="B", tz="America/New_York")
+    return pd.DataFrame(
+        {"Open": [183.0, 185.0], "High": [186.0, 187.5], "Low": [182.5, 184.2],
+         "Close": [185.0, 186.0], "Volume": [45_000_000, 50_000_000]},
+        index=idx,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Vendor-routing layer tests
+# ---------------------------------------------------------------------------
+
+class TestRouteToVendor:
+    """Tests for interface.route_to_vendor."""
+
+    def test_routes_stock_data_to_yfinance_by_default(self):
+        """With default config (yfinance), get_stock_data is routed to yfinance."""
+        from tradingagents.dataflows.interface import route_to_vendor
+
+        df = _make_yf_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = route_to_vendor("get_stock_data", "AAPL", "2024-01-04", "2024-01-05")
+
+        assert isinstance(result, str)
+        assert "AAPL" in result
+
+    def test_routes_stock_data_to_alpha_vantage_when_configured(self):
+        """When the vendor is overridden to alpha_vantage, the AV implementation is called."""
+        from tradingagents.dataflows.interface import route_to_vendor
+        from tradingagents.dataflows.config import get_config
+
+        original_config = get_config()
+        patched_config = {
+            **original_config,
+            "data_vendors": {**original_config.get("data_vendors", {}), "core_stock_apis": "alpha_vantage"},
+        }
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=patched_config):
+            with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                       return_value=_mock_av_response(_OHLCV_CSV_AV)):
+                with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                    result = route_to_vendor("get_stock_data", "AAPL", "2024-01-04", "2024-01-05")
+
+        assert isinstance(result, str)
+
+    def test_fallback_to_yfinance_when_alpha_vantage_rate_limited(self):
+        """When AV hits a rate limit, the router falls back to yfinance automatically."""
+        from tradingagents.dataflows.interface import route_to_vendor
+        from tradingagents.dataflows.config import get_config
+
+        original_config = get_config()
+        patched_config = {
+            **original_config,
+            "data_vendors": {**original_config.get("data_vendors", {}), "core_stock_apis": "alpha_vantage"},
+        }
+
+        df = _make_yf_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=patched_config):
+            # AV returns a rate-limit response
+            with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                       return_value=_mock_av_response(_RATE_LIMIT_JSON)):
+                with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                    # yfinance is the fallback
+                    with patch("tradingagents.dataflows.y_finance.yf.Ticker",
+                               return_value=mock_ticker):
+                        result = route_to_vendor(
+                            "get_stock_data", "AAPL", "2024-01-04", "2024-01-05"
+                        )
+
+        assert isinstance(result, str)
+        assert "AAPL" in result
+
+    def test_raises_runtime_error_when_all_vendors_fail(self):
+        """When every vendor fails, a RuntimeError is raised."""
+        from tradingagents.dataflows.interface import route_to_vendor
+        from tradingagents.dataflows.config import get_config
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        original_config = get_config()
+        patched_config = {
+            **original_config,
+            "data_vendors": {**original_config.get("data_vendors", {}), "core_stock_apis": "alpha_vantage"},
+        }
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=patched_config):
+            with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                       return_value=_mock_av_response(_RATE_LIMIT_JSON)):
+                with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                    with patch(
+                        "tradingagents.dataflows.y_finance.yf.Ticker",
+                        side_effect=ConnectionError("network unavailable"),
+                    ):
+                        with pytest.raises(RuntimeError, match="No available vendor"):
+                            route_to_vendor("get_stock_data", "AAPL", "2024-01-04", "2024-01-05")
+
+    def test_unknown_method_raises_value_error(self):
+        from tradingagents.dataflows.interface import route_to_vendor
+
+        with pytest.raises(ValueError):
+            route_to_vendor("nonexistent_method", "AAPL")
+
+
+# ---------------------------------------------------------------------------
+# Full pipeline: fetch → process → output
+# ---------------------------------------------------------------------------
+
+class TestFullPipeline:
+    """End-to-end tests that walk through the complete data retrieval pipeline."""
+
+    def test_yfinance_stock_data_pipeline(self):
+        """Fetch OHLCV data via yfinance, verify the formatted CSV output."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        df = _make_yf_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            raw = get_YFin_data_online("AAPL", "2024-01-04", "2024-01-05")
+
+        # Response structure checks
+        assert raw.startswith("# Stock data for AAPL")
+        assert "# Total records: 2" in raw
+        assert "Close" in raw  # CSV column
+        assert "186.0" in raw  # rounded close price
+
+    def test_alpha_vantage_stock_data_pipeline(self):
+        """Fetch OHLCV data via Alpha Vantage, verify the CSV output is filtered."""
+        from tradingagents.dataflows.alpha_vantage_stock import get_stock
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_av_response(_OHLCV_CSV_AV)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_stock("AAPL", "2024-01-04", "2024-01-05")
+
+        assert isinstance(result, str)
+        # pandas may reformat "185.00" → "185.0"; check for the numeric value
+        assert "185.0" in result or "186.0" in result
+
+    def test_yfinance_fundamentals_pipeline(self):
+        """Fetch company fundamentals via yfinance, verify key fields appear."""
+        from tradingagents.dataflows.y_finance import get_fundamentals
+
+        mock_info = {
+            "longName": "Apple Inc.",
+            "sector": "Technology",
+            "industry": "Consumer Electronics",
+            "marketCap": 3_000_000_000_000,
+            "trailingPE": 30.5,
+            "beta": 1.2,
+        }
+        mock_ticker = MagicMock()
+        type(mock_ticker).info = PropertyMock(return_value=mock_info)
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_fundamentals("AAPL")
+
+        assert "Apple Inc." in result
+        assert "Technology" in result
+        assert "30.5" in result
+
+    def test_alpha_vantage_fundamentals_pipeline(self):
+        """Fetch company overview via Alpha Vantage, verify key fields appear."""
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_fundamentals
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_av_response(_OVERVIEW_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_fundamentals("AAPL")
+
+        assert "Apple Inc" in result
+        assert "TECHNOLOGY" in result
+
+    def test_yfinance_news_pipeline(self):
+        """Fetch news via yfinance and verify basic response structure."""
+        from tradingagents.dataflows.yfinance_news import get_news_yfinance
+
+        mock_search = MagicMock()
+        mock_search.news = [
+            {
+                "title": "Apple Earnings Beat Expectations",
+                "publisher": "Reuters",
+                "link": "https://example.com",
+                "providerPublishTime": 1704499200,
+                "summary": "Apple reports Q1 earnings above estimates.",
+            }
+        ]
+
+        with patch("tradingagents.dataflows.yfinance_news.yf.Search", return_value=mock_search):
+            result = get_news_yfinance("AAPL", "2024-01-01", "2024-01-05")
+
+        assert isinstance(result, str)
+
+    def test_alpha_vantage_news_pipeline(self):
+        """Fetch ticker news via Alpha Vantage and verify basic response structure."""
+        from tradingagents.dataflows.alpha_vantage_news import get_news
+
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_av_response(_NEWS_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                result = get_news("AAPL", "2024-01-01", "2024-01-05")
+
+        assert "Apple Hits Record High" in result
+
+    def test_combined_yfinance_and_alpha_vantage_workflow(self):
+        """
+        Simulates a multi-source workflow:
+          1. Fetch stock price data from yfinance.
+          2. Fetch company fundamentals from Alpha Vantage.
+          3. Verify both results contain expected data and can be used together.
+        """
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_fundamentals
+
+        # --- Step 1: yfinance price data ---
+        df = _make_yf_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            price_data = get_YFin_data_online("AAPL", "2024-01-04", "2024-01-05")
+
+        # --- Step 2: Alpha Vantage fundamentals ---
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_av_response(_OVERVIEW_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                fundamentals = get_fundamentals("AAPL")
+
+        # --- Assertions ---
+        assert isinstance(price_data, str)
+        assert isinstance(fundamentals, str)
+
+        # Price data should reference the ticker
+        assert "AAPL" in price_data
+
+        # Fundamentals should contain company info
+        assert "Apple Inc" in fundamentals
+
+        # Both contain data – a real application could merge them here
+        combined_report = price_data + "\n\n" + fundamentals
+        assert "AAPL" in combined_report
+        assert "Apple Inc" in combined_report
+
+    def test_error_handling_in_combined_workflow(self):
+        """
+        When Alpha Vantage fails with a rate-limit error, the workflow can
+        continue with yfinance data alone – the error is surfaced rather than
+        silently swallowed.
+        """
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+        from tradingagents.dataflows.alpha_vantage_fundamentals import get_fundamentals
+        from tradingagents.dataflows.alpha_vantage_common import AlphaVantageRateLimitError
+
+        # yfinance succeeds
+        df = _make_yf_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            price_data = get_YFin_data_online("AAPL", "2024-01-04", "2024-01-05")
+
+        assert isinstance(price_data, str)
+        assert "AAPL" in price_data
+
+        # Alpha Vantage rate-limits
+        with patch("tradingagents.dataflows.alpha_vantage_common.requests.get",
+                   return_value=_mock_av_response(_RATE_LIMIT_JSON)):
+            with patch.dict("os.environ", {"ALPHA_VANTAGE_API_KEY": "demo"}):
+                with pytest.raises(AlphaVantageRateLimitError):
+                    get_fundamentals("AAPL")
+
+
+# ---------------------------------------------------------------------------
+# Vendor configuration and method routing
+# ---------------------------------------------------------------------------
+
+class TestVendorConfiguration:
+    """Tests for vendor configuration helpers in the interface module."""
+
+    def test_get_category_for_method_core_stock_apis(self):
+        from tradingagents.dataflows.interface import get_category_for_method
+
+        assert get_category_for_method("get_stock_data") == "core_stock_apis"
+
+    def test_get_category_for_method_fundamental_data(self):
+        from tradingagents.dataflows.interface import get_category_for_method
+
+        assert get_category_for_method("get_fundamentals") == "fundamental_data"
+
+    def test_get_category_for_method_news_data(self):
+        from tradingagents.dataflows.interface import get_category_for_method
+
+        assert get_category_for_method("get_news") == "news_data"
+
+    def test_get_category_for_unknown_method_raises_value_error(self):
+        from tradingagents.dataflows.interface import get_category_for_method
+
+        with pytest.raises(ValueError, match="not found"):
+            get_category_for_method("nonexistent_method")
+
+    def test_vendor_methods_contains_both_vendors_for_stock_data(self):
+        """Both yfinance and alpha_vantage implementations are registered."""
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+
+        assert "get_stock_data" in VENDOR_METHODS
+        assert "yfinance" in VENDOR_METHODS["get_stock_data"]
+        assert "alpha_vantage" in VENDOR_METHODS["get_stock_data"]
+
+    def test_vendor_methods_contains_both_vendors_for_news(self):
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+
+        assert "get_news" in VENDOR_METHODS
+        assert "yfinance" in VENDOR_METHODS["get_news"]
+        assert "alpha_vantage" in VENDOR_METHODS["get_news"]
diff --git a/tests/test_yfinance_integration.py b/tests/test_yfinance_integration.py
new file mode 100644
index 00000000..78bc88f3
--- /dev/null
+++ b/tests/test_yfinance_integration.py
@@ -0,0 +1,405 @@
+"""Integration tests for the yfinance data layer.
+
+All external network calls are mocked so these tests run offline and without
+rate-limit concerns.  The mocks reproduce realistic yfinance return shapes so
+that the code-under-test (y_finance.py) exercises every branch that matters.
+"""
+
+import pytest
+import pandas as pd
+from unittest.mock import patch, MagicMock, PropertyMock
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _make_ohlcv_df(start="2024-01-02", periods=5):
+    """Return a minimal OHLCV DataFrame with a timezone-aware DatetimeIndex."""
+    idx = pd.date_range(start, periods=periods, freq="B", tz="America/New_York")
+    return pd.DataFrame(
+        {
+            "Open":   [150.0, 151.0, 152.0, 153.0, 154.0][:periods],
+            "High":   [155.0, 156.0, 157.0, 158.0, 159.0][:periods],
+            "Low":    [148.0, 149.0, 150.0, 151.0, 152.0][:periods],
+            "Close":  [152.0, 153.0, 154.0, 155.0, 156.0][:periods],
+            "Volume": [1_000_000] * periods,
+        },
+        index=idx,
+    )
+
+
+# ---------------------------------------------------------------------------
+# get_YFin_data_online
+# ---------------------------------------------------------------------------
+
+class TestGetYFinDataOnline:
+    """Tests for get_YFin_data_online."""
+
+    def test_returns_csv_string_on_success(self):
+        """Valid symbol and date range returns a CSV-formatted string with header."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        df = _make_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_YFin_data_online("AAPL", "2024-01-02", "2024-01-08")
+
+        assert isinstance(result, str)
+        assert "# Stock data for AAPL" in result
+        assert "# Total records:" in result
+        assert "Close" in result  # CSV column header
+
+    def test_symbol_is_uppercased(self):
+        """Symbol is normalised to upper-case regardless of how it is supplied."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        df = _make_ohlcv_df()
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker) as mock_cls:
+            get_YFin_data_online("aapl", "2024-01-02", "2024-01-08")
+            mock_cls.assert_called_once_with("AAPL")
+
+    def test_empty_dataframe_returns_no_data_message(self):
+        """When yfinance returns an empty DataFrame a clear message is returned."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = pd.DataFrame()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_YFin_data_online("INVALID", "2024-01-02", "2024-01-08")
+
+        assert "No data found" in result
+        assert "INVALID" in result
+
+    def test_invalid_date_format_raises_value_error(self):
+        """Malformed date strings raise ValueError before any network call is made."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        with pytest.raises(ValueError):
+            get_YFin_data_online("AAPL", "2024/01/02", "2024-01-08")
+
+    def test_timezone_stripped_from_index(self):
+        """Timezone info is removed from the index for cleaner output."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        df = _make_ohlcv_df()
+        assert df.index.tz is not None  # pre-condition
+
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_YFin_data_online("AAPL", "2024-01-02", "2024-01-08")
+
+        # Timezone strings like "+00:00" or "UTC" should not appear in the CSV portion
+        csv_lines = result.split("\n")
+        data_lines = [l for l in csv_lines if l and not l.startswith("#")]
+        for line in data_lines:
+            assert "+00:00" not in line
+            assert "UTC" not in line
+
+    def test_numeric_columns_are_rounded(self):
+        """OHLC values in the returned CSV are rounded to 2 decimal places."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        idx = pd.date_range("2024-01-02", periods=1, freq="B", tz="UTC")
+        df = pd.DataFrame(
+            {"Open": [150.123456], "High": [155.987654], "Low": [148.0], "Close": [152.999999], "Volume": [1_000_000]},
+            index=idx,
+        )
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_YFin_data_online("AAPL", "2024-01-02", "2024-01-02")
+
+        assert "150.12" in result
+        assert "155.99" in result
+
+    def test_network_timeout_propagates(self):
+        """A TimeoutError from yfinance propagates to the caller."""
+        from tradingagents.dataflows.y_finance import get_YFin_data_online
+
+        mock_ticker = MagicMock()
+        mock_ticker.history.side_effect = TimeoutError("request timed out")
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            with pytest.raises(TimeoutError):
+                get_YFin_data_online("AAPL", "2024-01-02", "2024-01-08")
+
+
+# ---------------------------------------------------------------------------
+# get_fundamentals
+# ---------------------------------------------------------------------------
+
+class TestGetFundamentals:
+    """Tests for the yfinance get_fundamentals function."""
+
+    def test_returns_fundamentals_string_on_success(self):
+        """When info is populated, fundamentals are returned as a formatted string."""
+        from tradingagents.dataflows.y_finance import get_fundamentals
+
+        mock_info = {
+            "longName": "Apple Inc.",
+            "sector": "Technology",
+            "industry": "Consumer Electronics",
+            "marketCap": 3_000_000_000_000,
+            "trailingPE": 30.5,
+            "beta": 1.2,
+            "fiftyTwoWeekHigh": 200.0,
+            "fiftyTwoWeekLow": 150.0,
+        }
+        mock_ticker = MagicMock()
+        type(mock_ticker).info = PropertyMock(return_value=mock_info)
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_fundamentals("AAPL")
+
+        assert "# Company Fundamentals for AAPL" in result
+        assert "Apple Inc." in result
+        assert "Technology" in result
+
+    def test_empty_info_returns_no_data_message(self):
+        """Empty info dict returns a clear 'no data' message."""
+        from tradingagents.dataflows.y_finance import get_fundamentals
+
+        mock_ticker = MagicMock()
+        type(mock_ticker).info = PropertyMock(return_value={})
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_fundamentals("AAPL")
+
+        assert "No fundamentals data" in result
+
+    def test_exception_returns_error_string(self):
+        """An exception from yfinance yields a safe error string (not a raise)."""
+        from tradingagents.dataflows.y_finance import get_fundamentals
+
+        mock_ticker = MagicMock()
+        type(mock_ticker).info = PropertyMock(side_effect=ConnectionError("network error"))
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_fundamentals("AAPL")
+
+        assert "Error" in result
+        assert "AAPL" in result
+
+
+# ---------------------------------------------------------------------------
+# get_balance_sheet
+# ---------------------------------------------------------------------------
+
+class TestGetBalanceSheet:
+    """Tests for yfinance get_balance_sheet."""
+
+    def _mock_balance_df(self):
+        return pd.DataFrame(
+            {"2023-12-31": [1_000_000], "2022-12-31": [900_000]},
+            index=["Total Assets"],
+        )
+
+    def test_quarterly_balance_sheet_success(self):
+        from tradingagents.dataflows.y_finance import get_balance_sheet
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_balance_sheet = self._mock_balance_df()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_balance_sheet("AAPL", freq="quarterly")
+
+        assert "# Balance Sheet data for AAPL (quarterly)" in result
+        assert "Total Assets" in result
+
+    def test_annual_balance_sheet_success(self):
+        from tradingagents.dataflows.y_finance import get_balance_sheet
+
+        mock_ticker = MagicMock()
+        mock_ticker.balance_sheet = self._mock_balance_df()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_balance_sheet("AAPL", freq="annual")
+
+        assert "# Balance Sheet data for AAPL (annual)" in result
+
+    def test_empty_dataframe_returns_no_data_message(self):
+        from tradingagents.dataflows.y_finance import get_balance_sheet
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_balance_sheet = pd.DataFrame()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_balance_sheet("AAPL")
+
+        assert "No balance sheet data" in result
+
+    def test_exception_returns_error_string(self):
+        from tradingagents.dataflows.y_finance import get_balance_sheet
+
+        mock_ticker = MagicMock()
+        type(mock_ticker).quarterly_balance_sheet = PropertyMock(
+            side_effect=ConnectionError("network error")
+        )
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_balance_sheet("AAPL")
+
+        assert "Error" in result
+
+
+# ---------------------------------------------------------------------------
+# get_cashflow
+# ---------------------------------------------------------------------------
+
+class TestGetCashflow:
+    """Tests for yfinance get_cashflow."""
+
+    def _mock_cashflow_df(self):
+        return pd.DataFrame(
+            {"2023-12-31": [500_000]},
+            index=["Free Cash Flow"],
+        )
+
+    def test_quarterly_cashflow_success(self):
+        from tradingagents.dataflows.y_finance import get_cashflow
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_cashflow = self._mock_cashflow_df()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_cashflow("AAPL", freq="quarterly")
+
+        assert "# Cash Flow data for AAPL (quarterly)" in result
+        assert "Free Cash Flow" in result
+
+    def test_empty_dataframe_returns_no_data_message(self):
+        from tradingagents.dataflows.y_finance import get_cashflow
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_cashflow = pd.DataFrame()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_cashflow("AAPL")
+
+        assert "No cash flow data" in result
+
+    def test_exception_returns_error_string(self):
+        from tradingagents.dataflows.y_finance import get_cashflow
+
+        mock_ticker = MagicMock()
+        type(mock_ticker).quarterly_cashflow = PropertyMock(
+            side_effect=ConnectionError("network error")
+        )
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_cashflow("AAPL")
+
+        assert "Error" in result
+
+
+# ---------------------------------------------------------------------------
+# get_income_statement
+# ---------------------------------------------------------------------------
+
+class TestGetIncomeStatement:
+    """Tests for yfinance get_income_statement."""
+
+    def _mock_income_df(self):
+        return pd.DataFrame(
+            {"2023-12-31": [400_000]},
+            index=["Total Revenue"],
+        )
+
+    def test_quarterly_income_statement_success(self):
+        from tradingagents.dataflows.y_finance import get_income_statement
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_income_stmt = self._mock_income_df()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_income_statement("AAPL", freq="quarterly")
+
+        assert "# Income Statement data for AAPL (quarterly)" in result
+        assert "Total Revenue" in result
+
+    def test_empty_dataframe_returns_no_data_message(self):
+        from tradingagents.dataflows.y_finance import get_income_statement
+
+        mock_ticker = MagicMock()
+        mock_ticker.quarterly_income_stmt = pd.DataFrame()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_income_statement("AAPL")
+
+        assert "No income statement data" in result
+
+
+# ---------------------------------------------------------------------------
+# get_insider_transactions
+# ---------------------------------------------------------------------------
+
+class TestGetInsiderTransactions:
+    """Tests for yfinance get_insider_transactions."""
+
+    def _mock_insider_df(self):
+        return pd.DataFrame(
+            {
+                "Date": ["2024-01-15"],
+                "Insider": ["Tim Cook"],
+                "Transaction": ["Sale"],
+                "Shares": [10000],
+                "Value": [1_500_000],
+            }
+        )
+
+    def test_returns_csv_string_with_header(self):
+        from tradingagents.dataflows.y_finance import get_insider_transactions
+
+        mock_ticker = MagicMock()
+        mock_ticker.insider_transactions = self._mock_insider_df()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_insider_transactions("AAPL")
+
+        assert "# Insider Transactions data for AAPL" in result
+        assert "Tim Cook" in result
+
+    def test_none_data_returns_no_data_message(self):
+        from tradingagents.dataflows.y_finance import get_insider_transactions
+
+        mock_ticker = MagicMock()
+        mock_ticker.insider_transactions = None
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_insider_transactions("AAPL")
+
+        assert "No insider transactions data" in result
+
+    def test_empty_dataframe_returns_no_data_message(self):
+        from tradingagents.dataflows.y_finance import get_insider_transactions
+
+        mock_ticker = MagicMock()
+        mock_ticker.insider_transactions = pd.DataFrame()
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_insider_transactions("AAPL")
+
+        assert "No insider transactions data" in result
+
+    def test_exception_returns_error_string(self):
+        from tradingagents.dataflows.y_finance import get_insider_transactions
+
+        mock_ticker = MagicMock()
+        type(mock_ticker).insider_transactions = PropertyMock(
+            side_effect=ConnectionError("network error")
+        )
+
+        with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+            result = get_insider_transactions("AAPL")
+
+        assert "Error" in result