Add tests for Buy and Hold strategy

tests/strategies/test_buy_and_hold.py

@@ -0,0 +1,80 @@
+from datetime import date, timedelta
+
+import polars as pl
+from quant_trading_strategy_backtester.strategies.buy_and_hold import BuyAndHoldStrategy
+
+
+def test_buy_and_hold_strategy_initialisation() -> None:
+    params = {}  # Buy and Hold doesn't require parameters
+    strategy = BuyAndHoldStrategy(params)
+    assert isinstance(strategy, BuyAndHoldStrategy)
+
+
+def test_buy_and_hold_strategy_generate_signals(mock_polars_data: pl.DataFrame) -> None:
+    params = {}
+    strategy = BuyAndHoldStrategy(params)
+    signals = strategy.generate_signals(mock_polars_data)
+    assert isinstance(signals, pl.DataFrame)
+    EXPECTED_COLS = {"Date", "Close", "signal", "positions"}
+    assert all(col in signals.columns for col in EXPECTED_COLS)
+    assert (signals["signal"] == 1).all(), "All signals should be 1 (buy)"
+    assert (signals["positions"] == 1).all(), "All positions should be 1"
+
+
+def test_buy_and_hold_strategy_with_mock_data():
+    # Create mock data
+    start_date = date(2023, 1, 1)
+    dates = [start_date + timedelta(days=i) for i in range(100)]
+    prices = [100 + i for i in range(100)]  # Steadily increasing prices
+
+    mock_polars_data = pl.DataFrame({"Date": dates, "Close": prices})
+
+    params = {}
+    strategy = BuyAndHoldStrategy(params)
+
+    # Generate signals
+    signals = strategy.generate_signals(mock_polars_data)
+
+    # Check if signals are generated correctly
+    assert signals["signal"].sum() == len(signals), "All signals should be buy (1)"
+    assert (signals["positions"] == 1).all(), "All positions should be 1"
+
+    # Check if the strategy maintains the buy position throughout
+    assert (signals["signal"] == 1).all(), "Buy signal should be maintained throughout"
+
+
+def test_buy_and_hold_strategy_with_empty_data():
+    empty_data = pl.DataFrame(schema=[("Date", pl.Date), ("Close", pl.Float64)])
+    params = {}
+    strategy = BuyAndHoldStrategy(params)
+    signals = strategy.generate_signals(empty_data)
+
+    assert isinstance(signals, pl.DataFrame)
+    assert signals.is_empty()
+    EXPECTED_COLS = {"Date", "Close", "signal", "positions"}
+    assert all(col in signals.columns for col in EXPECTED_COLS)
+
+
+def test_buy_and_hold_strategy_with_various_price_movements():
+    # Create mock data with various price movements
+    start_date = date(2023, 1, 1)
+    dates = [start_date + timedelta(days=i) for i in range(100)]
+
+    # Prices that go up, down, and sideways
+    prices = (
+        [100 + i for i in range(30)]  # Uptrend
+        + [130 - i for i in range(30)]  # Downtrend
+        + [100] * 40  # Sideways
+    )
+
+    mock_polars_data = pl.DataFrame({"Date": dates, "Close": prices})
+
+    params = {}
+    strategy = BuyAndHoldStrategy(params)
+
+    # Generate signals
+    signals = strategy.generate_signals(mock_polars_data)
+
+    # Check if the strategy maintains the buy position regardless of price movements
+    assert (signals["signal"] == 1).all(), "Buy signal should be maintained throughout"
+    assert (signals["positions"] == 1).all(), "All positions should be 1"