Raises error if sell/cover_all_shares is called without open position.

src/pybroker/context.py

@@ -829,7 +829,9 @@ def sell_all_shares(self):
         """Sells all long shares of :attr:`.ExecContext.symbol`."""
         pos = self.long_pos()
         if pos is None:
-            return
+            raise ValueError(
+                f"sell_all_shares failed: No long position for {self.symbol}"
+            )
         self.sell_shares = pos.shares
         self._portfolio.remove_stops(pos)
         self._exiting_pos = True
@@ -838,7 +840,9 @@ def cover_all_shares(self):
         """Covers all short shares of :attr:`.ExecContext.symbol`."""
         pos = self.short_pos()
         if pos is None:
-            return
+            raise ValueError(
+                f"cover_all_shares failed: No short position for {self.symbol}"
+            )
         self.cover_shares = pos.shares
         self._portfolio.remove_stops(pos)
         self._exiting_pos = True
@@ -1304,6 +1308,7 @@ def to_result(self) -> Optional[ExecResult]:
                     "sell_shares or hold_bars must be set when "
                     "sell_fill_price is set."
                 )
+
         if self.buy_shares is None and self.sell_shares is None:
             if (
                 self.stop_loss is not None

tests/test_context.py

@@ -263,8 +263,11 @@ def test_sell_all_shares(ctx_with_pos):
 
 
 def test_sell_all_shares_when_no_position(ctx):
-    ctx.sell_all_shares()
-    assert ctx.sell_shares is None
+    with pytest.raises(
+        ValueError,
+        match=re.escape("sell_all_shares failed: No long position for SPY"),
+    ):
+        ctx.sell_all_shares()
 
 
 def test_cover_all_shares(ctx_with_pos):
@@ -274,8 +277,11 @@ def test_cover_all_shares(ctx_with_pos):
 
 
 def test_cover_all_shares_when_no_position(ctx):
-    ctx.cover_all_shares()
-    assert ctx.buy_shares is None
+    with pytest.raises(
+        ValueError,
+        match=re.escape("cover_all_shares failed: No short position for SPY"),
+    ):
+        ctx.cover_all_shares()
 
 
 def test_model(ctx, trained_models, symbol):

tests/test_strategy.py

@@ -2378,7 +2378,7 @@ def test_backtest_when_no_stops(self, data_source_df):
         def exec_fn(ctx):
             if ctx.bars == 1:
                 ctx.buy_shares = 100
-            elif ctx.bars > 30:
+            elif ctx.long_pos() and ctx.bars > 30:
                 ctx.sell_all_shares()
 
         strategy = Strategy(data_source_df, START_DATE, END_DATE)