test: add tests for 1D party position chart

tests/test_explorer_chart.py

@@ -278,3 +278,63 @@ def test_partial_party_traces():
         # hovertemplate should include raw marker fields like 'x (raw)'
         if hasattr(tr, "hovertemplate") and tr.hovertemplate:
             assert "x (raw)" in tr.hovertemplate
+
+
+def test_render_party_axis_chart_1d_renders():
+    """Test that _render_party_axis_chart_1d creates a figure with proper structure."""
+    from unittest.mock import MagicMock, patch
+
+    from explorer import _render_party_axis_chart_1d
+
+    party_coords = {
+        "VVD": (0.5,),
+        "SP": (-0.6,),
+        "PVV": (0.8,),
+        "DENK": (-0.4,),
+    }
+
+    theme = {
+        "label": "Test Component",
+        "positive_pole": "Positive",
+        "negative_pole": "Negative",
+        "flip": False,
+    }
+
+    # Mock st.plotly_chart to capture the figure being rendered
+    with patch("explorer.st.plotly_chart") as mock_plotly_chart:
+        _render_party_axis_chart_1d(party_coords, 3, theme)
+
+        # Verify that plotly_chart was called
+        assert mock_plotly_chart.called, "plotly_chart should be called"
+
+        # Get the figure passed to plotly_chart
+        fig = mock_plotly_chart.call_args[0][0]
+        assert fig is not None, "Figure should not be None"
+        # Check that figure has traces (the bar chart)
+        assert len(fig.data) > 0, "Figure should have traces"
+
+
+def test_render_party_axis_chart_1d_empty_coords():
+    """Test that _render_party_axis_chart_1d handles empty coords gracefully."""
+    from unittest.mock import patch
+
+    from explorer import _render_party_axis_chart_1d
+
+    theme = {
+        "label": "Test Component",
+        "positive_pole": "Positive",
+        "negative_pole": "Negative",
+        "flip": False,
+    }
+
+    # Empty coords should show caption, not plotly_chart
+    with patch("explorer.st.caption") as mock_caption:
+        with patch("explorer.st.plotly_chart") as mock_plotly_chart:
+            result = _render_party_axis_chart_1d({}, 3, theme)
+
+            # Should show caption for empty data
+            assert mock_caption.called, "Should show caption for empty data"
+            # Should NOT call plotly_chart
+            assert not mock_plotly_chart.called, (
+                "Should not call plotly_chart for empty data"
+            )