Added tests for legend_loc

Author: mittal-aakriti

pandas/tests/plotting/frame/test_frame_legend.py

@@ -11,6 +11,7 @@
     _check_legend_labels,
     _check_legend_marker,
     _check_text_labels,
+    _check_plot_works,
 )
 
 mpl = pytest.importorskip("matplotlib")
@@ -260,3 +261,55 @@ def test_missing_markers_legend_using_style(self):
 
         _check_legend_labels(ax, labels=["A", "B", "C"])
         _check_legend_marker(ax, expected_markers=[".", ".", "."])
+
+    def test_no_legend_when_legend_false_legend_loc(self):
+        df = DataFrame({"a": [1, 2, 3]})
+        ax = _check_plot_works(df.plot, legend=False, legend_loc="upper right")
+        assert ax.get_legend() is None
+
+    def test_df_legend_labels_secondary_y_legend_loc(self):
+        pytest.importorskip("scipy")
+        df = DataFrame(np.random.default_rng(2).random((3, 3)), columns=["a", "b", "c"])
+        df2 = DataFrame(
+            np.random.default_rng(2).random((3, 3)), columns=["d", "e", "f"]
+        )
+        df3 = DataFrame(
+            np.random.default_rng(2).random((3, 3)), columns=["g", "h", "i"]
+        )
+
+        # preserves "best" behaviour if no legend_loc specified
+        ax = df.plot(legend=True, secondary_y="b", legend_loc=None)
+        _check_legend_labels(ax, labels=["a", "b (right)", "c"])
+        ax = df2.plot(legend=False, ax=ax)
+        _check_legend_labels(ax, labels=["a", "b (right)", "c"])
+        ax = df3.plot(kind="bar", legend=True, secondary_y="h", legend_loc="upper right", ax=ax)
+        _check_legend_labels(ax, labels=["a", "b (right)", "c", "g", "h (right)", "i"])
+
+    @pytest.mark.parametrize(
+            "kind, labels",
+            [
+                ("line", ["a", "b"]),
+                ("bar",  ["a", "b"]),
+                ("scatter", ["b"]),  # scatter(x="a", y="b") usually labels the y series
+                ])
+    def test_across_kinds_legend_loc(self, kind, labels):
+        df = DataFrame({"a": [1, 2, 3], "b": [3, 2, 1]})
+        if kind == "scatter":
+            ax = _check_plot_works(
+                df.plot,
+                kind="scatter",
+                x="a",
+                y="b",
+                label="b",
+                legend=True,
+                legend_loc="upper right"
+            )
+        else:
+            ax = _check_plot_works(
+                df.plot,
+                kind=kind,
+                legend=True,
+                legend_loc="upper right"
+                )
+        _check_legend_labels(ax, labels=labels)
+        assert ax.get_legend() is not None