1 files changed, 73 insertions, 0 deletions
diff --git a/services/backtester/tests/test_simulator.py b/services/backtester/tests/test_simulator.py
new file mode 100644
index 0000000..9d8b23e
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+++ b/services/backtester/tests/test_simulator.py
@@ -0,0 +1,73 @@
+"""Tests for the OrderSimulator."""
+from decimal import Decimal
+
+import pytest
+
+from shared.models import Signal, OrderSide, OrderType
+from backtester.simulator import OrderSimulator
+
+
+def make_signal(
+    symbol: str,
+    side: OrderSide,
+    price: str,
+    quantity: str,
+    strategy: str = "test",
+) -> Signal:
+    return Signal(
+        strategy=strategy,
+        symbol=symbol,
+        side=side,
+        price=Decimal(price),
+        quantity=Decimal(quantity),
+        reason="test",
+    )
+
+
+def test_simulator_initial_balance():
+    sim = OrderSimulator(Decimal("10000"))
+    assert sim.balance == Decimal("10000")
+
+
+def test_simulator_buy_reduces_balance():
+    sim = OrderSimulator(Decimal("10000"))
+    signal = make_signal("BTCUSDT", OrderSide.BUY, "50000", "0.1")
+    result = sim.execute(signal)
+    assert result is True
+    assert sim.balance == Decimal("5000")
+    assert sim.positions["BTCUSDT"] == Decimal("0.1")
+
+
+def test_simulator_sell_increases_balance():
+    sim = OrderSimulator(Decimal("10000"))
+    buy_signal = make_signal("BTCUSDT", OrderSide.BUY, "50000", "0.1")
+    sim.execute(buy_signal)
+    balance_after_buy = sim.balance
+
+    sell_signal = make_signal("BTCUSDT", OrderSide.SELL, "55000", "0.1")
+    result = sim.execute(sell_signal)
+    assert result is True
+    assert sim.balance > balance_after_buy
+    # Profit: sold at 55000, bought at 50000 → gain 500
+    assert sim.balance == Decimal("10000") - Decimal("5000") + Decimal("5500")
+
+
+def test_simulator_reject_buy_insufficient_balance():
+    sim = OrderSimulator(Decimal("100"))
+    signal = make_signal("BTCUSDT", OrderSide.BUY, "50000", "0.1")
+    result = sim.execute(signal)
+    assert result is False
+    assert sim.balance == Decimal("100")
+    assert sim.positions.get("BTCUSDT", Decimal("0")) == Decimal("0")
+
+
+def test_simulator_trade_history():
+    sim = OrderSimulator(Decimal("10000"))
+    signal = make_signal("BTCUSDT", OrderSide.BUY, "50000", "0.1")
+    sim.execute(signal)
+    assert len(sim.trades) == 1
+    trade = sim.trades[0]
+    assert trade.symbol == "BTCUSDT"
+    assert trade.side == OrderSide.BUY
+    assert trade.price == Decimal("50000")
+    assert trade.quantity == Decimal("0.1")