fix: Honor window_span and end_type kwargs in get_fractal

stock_indicators/indicators/fractal.py

@@ -26,7 +26,12 @@ def get_fractal(
 
 
 def get_fractal(
-    quotes, left_span=None, right_span=EndType.HIGH_LOW, end_type=EndType.HIGH_LOW
+    quotes,
+    left_span=None,
+    right_span=None,
+    end_type=None,
+    *,
+    window_span=None,
 ):
     """Get Williams Fractal calculated.
 
@@ -57,11 +62,35 @@ def get_fractal(
          - [Williams Fractal Reference](https://python.stockindicators.dev/indicators/Fractal/#content)
          - [Helper Methods](https://python.stockindicators.dev/utilities/#content)
     """
+    # `window_span` is the documented name for the symmetric form's span.
+    # It is an alternative to the left/right span pair, not a third span,
+    # so it cannot be combined with either span argument.
+    if window_span is not None:
+        if left_span is not None or right_span is not None:
+            raise TypeError(
+                "window_span cannot be combined with left_span or right_span"
+            )
+        left_span = window_span
+
+    # In the symmetric form the second positional argument is `end_type`,
+    # not `right_span`: get_fractal(quotes, 2, EndType.CLOSE)
     if isinstance(right_span, EndType):
-        if left_span is None:
-            left_span = 2
+        if end_type is not None and end_type != right_span:
+            raise ValueError(
+                "end_type was given twice with different values: "
+                f"{right_span} and {end_type}"
+            )
+        end_type = right_span
+        right_span = None
+
+    if left_span is None:
+        left_span = 2
+    if end_type is None:
+        end_type = EndType.HIGH_LOW
+
+    if right_span is None:
         fractal_results = CsIndicator.GetFractal[Quote](
-            CsList(Quote, quotes), left_span, right_span.cs_value
+            CsList(Quote, quotes), left_span, end_type.cs_value
         )
     else:
         fractal_results = CsIndicator.GetFractal[Quote](

tests/test_fractal.py

@@ -67,6 +67,75 @@ def test_standard_span_4(self, quotes):
         assert r.fractal_bear is None
         assert r.fractal_bull is None
 
+    def test_window_span_keyword(self, quotes):
+        # Documented form: get_fractal(quotes, window_span=4, end_type=...).
+        # A non-default span, so an ignored keyword would change the result.
+        results = indicators.get_fractal(quotes, window_span=4)
+
+        assert 502 == len(results)
+        assert 35 == len(list(filter(lambda x: x.fractal_bear is not None, results)))
+        assert 34 == len(list(filter(lambda x: x.fractal_bull is not None, results)))
+
+        r = results[7]
+        assert r.fractal_bear is None
+        assert 212.53 == round(float(r.fractal_bull), 2)
+
+    def test_window_span_with_end_type_keyword(self, quotes):
+        results = indicators.get_fractal(quotes, window_span=2, end_type=EndType.CLOSE)
+        positional = indicators.get_fractal(quotes, 2, EndType.CLOSE)
+
+        assert 64 == len(list(filter(lambda x: x.fractal_bear is not None, results)))
+        assert 69 == len(list(filter(lambda x: x.fractal_bull is not None, results)))
+
+        for keyword_result, positional_result in zip(results, positional):
+            assert keyword_result.fractal_bear == positional_result.fractal_bear
+            assert keyword_result.fractal_bull == positional_result.fractal_bull
+
+    def test_end_type_keyword_window_form(self, quotes):
+        # end_type given as a keyword in the window-span form must not be
+        # silently ignored: it must match the positional EndType form.
+        results = indicators.get_fractal(quotes, 2, end_type=EndType.CLOSE)
+        positional = indicators.get_fractal(quotes, 2, EndType.CLOSE)
+
+        assert 64 == len(list(filter(lambda x: x.fractal_bear is not None, results)))
+        assert 69 == len(list(filter(lambda x: x.fractal_bull is not None, results)))
+
+        for keyword_result, positional_result in zip(results, positional):
+            assert keyword_result.fractal_bear == positional_result.fractal_bear
+            assert keyword_result.fractal_bull == positional_result.fractal_bull
+
+    def test_end_type_keyword_only(self, quotes):
+        results = indicators.get_fractal(quotes, end_type=EndType.CLOSE)
+
+        assert 64 == len(list(filter(lambda x: x.fractal_bear is not None, results)))
+        assert 69 == len(list(filter(lambda x: x.fractal_bull is not None, results)))
+
+    def test_end_type_keyword_asymmetric_form(self, quotes):
+        results = indicators.get_fractal(quotes, 4, 4, end_type=EndType.HIGH_LOW)
+        positional = indicators.get_fractal(quotes, 4, 4, EndType.HIGH_LOW)
+
+        for keyword_result, positional_result in zip(results, positional):
+            assert keyword_result.fractal_bear == positional_result.fractal_bear
+            assert keyword_result.fractal_bull == positional_result.fractal_bull
+
+    def test_window_span_conflicts_raise(self, quotes):
+        with pytest.raises(TypeError, match="window_span cannot be combined"):
+            indicators.get_fractal(quotes, 2, 3, window_span=4)
+        with pytest.raises(TypeError, match="window_span cannot be combined"):
+            indicators.get_fractal(quotes, window_span=2, right_span=2)
+        with pytest.raises(TypeError, match="window_span cannot be combined"):
+            indicators.get_fractal(quotes, left_span=2, window_span=2)
+
+    def test_end_type_conflict_raises(self, quotes):
+        with pytest.raises(ValueError, match="end_type was given twice"):
+            indicators.get_fractal(quotes, 2, EndType.CLOSE, end_type=EndType.HIGH_LOW)
+
+        # The same value given twice is not a conflict.
+        results = indicators.get_fractal(
+            quotes, 2, EndType.CLOSE, end_type=EndType.CLOSE
+        )
+        assert 64 == len(list(filter(lambda x: x.fractal_bear is not None, results)))
+
     def test_no_data(self, quotes):
         r = indicators.get_fractal([])
         assert 0 == len(r)