add tests for double y-axis realignments

Author: TeemuSailynoja

tests/mmm/test_plot.py

@@ -1081,6 +1081,61 @@ def test__dim_list_handler_mixed():
     assert set(combos) == {("A",), ("B",)}
 
 
+class TestAlignYAxes:
+    """Test the _align_y_axes method with various axis configurations."""
+
+    @pytest.fixture
+    def mock_axes(self):
+        """Create mock axes for testing."""
+        _, ax = plt.subplots()
+        ax2 = ax.twinx()
+        return ax, ax2
+
+    @pytest.mark.parametrize(
+        "ax1_limits,ax2_limits,expected_ax1_limits,expected_ax2_limits,description",
+        [
+            ((0, 10), (0, 20), (0, 10), (0, 20), "both_positive"),
+            ((-10, 0), (-20, 0), (-10, 0), (-20, 0), "both_negative"),
+            ((-5, 10), (0, 20), (-5, 10), (-10, 20), "ax1_mixed_ax2_positive"),
+            ((-10, 0), (-5, 20), (-10, 40), (-5, 20), "ax1_negative_ax2_mixed"),
+            ((-2, 10), (-5, 20), (-2.5, 10), (-5, 20), "both_mixed_ax1_ratio_smaller"),
+            ((-5, 10), (-2, 20), (-5, 10), (-10, 20), "both_mixed_ax2_ratio_smaller"),
+            ((-10, 0), (0, 20), (-10, 10), (-20, 20), "ax1_fully_negative"),
+            ((-2, 0), (0, 10), (-2, 2), (-10, 10), "ax2_fully_negative"),
+        ],
+    )
+    def test_align_y_axes_various_scenarios(
+        self,
+        mock_axes,
+        ax1_limits,
+        ax2_limits,
+        expected_ax1_limits,
+        expected_ax2_limits,
+        description,
+    ):
+        """Test _align_y_axes with various axis limit scenarios."""
+        ax, ax2 = mock_axes
+        suite = MMMPlotSuite(az.InferenceData())
+
+        # Set initial limits
+        ax.set_ylim(ax1_limits)
+        ax2.set_ylim(ax2_limits)
+
+        # Call the method
+        suite._align_y_axes(ax, ax2)
+
+        # Check results
+        actual_ax1_limits = ax.get_ylim()
+        actual_ax2_limits = ax2.get_ylim()
+
+        assert actual_ax1_limits == pytest.approx(expected_ax1_limits, rel=1e-10), (
+            f"Axis 1 limits incorret in: {description}"
+        )
+        assert actual_ax2_limits == pytest.approx(expected_ax2_limits, rel=1e-10), (
+            f"Axis 2 limits incorret in: {description}"
+        )
+
+
 class TestPlotBudgetAllocationBars:
     """Test the _plot_budget_allocation_bars method and its integration with _align_y_axes."""