Add test for mdraw_legend (#88, #89) (#94)

* Add test for mdraw_legend (#88, #89)

* Troubleshooting older py/mpl ver

* Troubleshooting older py/mpl ver

* Pleasing linters

forestplot/mplot_graph_utils.py

@@ -242,6 +242,41 @@ def mdraw_legend(
     mcolor: Union[Sequence[str], None] = ["0", "0.4", ".8", "0.2"],
     **kwargs: Any,
 ) -> Axes:
+    """
+    Add a custom legend to a matplotlib Axes object for the different models.
+
+    This function creates and adds a legend to a given Axes object, allowing for customization of
+    the legend's markers, colors, size, and positioning. It's particularly useful for graphs
+    representing different models or categories with distinct markers and colors.
+
+    Parameters
+    ----------
+    ax : Axes
+        The matplotlib Axes object to which the legend will be added.
+    xlabel : Union[Sequence[str], None]
+        A sequence of strings for x-axis labels, used to adjust the legend position. If None, the default position is used.
+    modellabels : Optional[Union[Sequence[str], None]]
+        A sequence of strings that serve as labels for the legend entries.
+    msymbols : Union[Sequence[str], None], optional
+        A sequence of marker symbols for each legend entry, defaults to 'soDx'.
+    mcolor : Union[Sequence[str], None], optional
+        A sequence of colors for each legend entry, defaults to ["0", "0.4", ".8", "0.2"].
+    **kwargs : Any
+        Additional keyword arguments for further customization. Supported customizations include 'leg_markersize'
+        (size of the legend markers, default 8), 'bbox_to_anchor' (tuple specifying the anchor point of the legend),
+        'leg_loc' (location of the legend, default 'lower center' or 'best'), 'leg_ncol' (number of columns in the legend,
+        default 2 or 1), and 'leg_fontsize' (font size of legend text, default 12).
+
+    Returns
+    -------
+    Axes
+        The modified matplotlib Axes object with the legend added.
+
+    Notes
+    -----
+    - The 'xlabel' parameter is used to adjust the legend's position based on the presence of x-axis labels.
+      It does not directly set the x-axis labels.
+    """
     leg_markersize = kwargs.get("leg_markersize", 8)
     leg_artists = []
     for ix, symbol in enumerate(msymbols):

tests/test_mplot_graph_utils.py

@@ -1,10 +1,12 @@
 import matplotlib.pyplot as plt
 import pandas as pd
+from matplotlib.lines import Line2D
 from matplotlib.pyplot import Axes
 
 from forestplot.mplot_graph_utils import (
     mdraw_ci,
     mdraw_est_markers,
+    mdraw_legend,
     mdraw_ref_xline,
     mdraw_yticklabels,
 )
@@ -95,3 +97,33 @@ def test_mdraw_ci():
     # Assertions
     assert isinstance(ax, Axes)
     assert len(ax.collections) == len(set(models_vector))
+
+def test_mdraw_legend():
+    # Create a simple plot
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1], marker="o", color="0")
+    ax.plot([0, 1], [1, 0], marker="s", color="0.4")
+
+    # Sample parameters for the legend
+    modellabels = ["Model 1", "Model 2"]
+    msymbols = ["o", "s"]
+    mcolor = ["0", "0.4"]
+
+    # Call the function
+    ax = mdraw_legend(ax, None, modellabels, msymbols, mcolor)
+
+    # Assertions
+    legend = ax.get_legend()
+    assert legend is not None, "Legend was not created."
+
+    # Check number of legend entries
+    assert len(legend.get_texts()) == len(modellabels), "Incorrect number of legend entries."
+
+    # Check legend labels
+    for label, model_label in zip(legend.get_texts(), modellabels):
+        assert label.get_text() == model_label, "Legend labels do not match."
+
+    # Check legend marker colors and symbols
+    for line, color in zip(legend.legendHandles, mcolor):
+        assert isinstance(line, Line2D), "Legend entry is not a Line2D instance."
+        assert line.get_color() == color, "Legend marker color does not match."