New tests to increase coverage

Author: ianthomas23

lib/matplotlib/tests/baseline_images/test_contour/contour_line_start_on_corner_edge.png

@@ -410,3 +410,59 @@ def test_contour_closed_line_loop():
     ax.contour(z, [0.5], linewidths=[20], alpha=0.7)
     ax.set_xlim(-0.1, 2.1)
     ax.set_ylim(-0.1, 3.1)
+
+
+def test_quadcontourset_reuse():
+    # If QuadContourSet returned from one contour(f) call is passed as first
+    # argument to another the underlying C++ contour generator will be reused.
+    x, y = np.meshgrid([0.0, 1.0], [0.0, 1.0])
+    z = x + y
+    fig, ax = plt.subplots()
+    qcs1 = ax.contourf(x, y, z)
+    qcs2 = ax.contour(x, y, z)
+    assert qcs2._contour_generator != qcs1._contour_generator
+    qcs3 = ax.contour(qcs1, z)
+    assert qcs3._contour_generator == qcs1._contour_generator
+
+
+@image_comparison(baseline_images=['contour_manual'],
+                  extensions=['png'], remove_text=True)
+def test_contour_manual():
+    # Manually specifying contour lines/polygons to plot.
+    from matplotlib.contour import ContourSet
+
+    fig, ax = plt.subplots(figsize=(4, 4))
+    cmap = 'viridis'
+
+    # Segments only (no 'kind' codes).
+    lines0 = [[[2, 0], [1, 2], [1, 3]]]  # Single line.
+    lines1 = [[[3, 0], [3, 2]], [[3, 3], [3, 4]]]  # Two lines.
+    filled01 = [[[0, 0], [0, 4], [1, 3], [1, 2], [2, 0]]]
+    filled12 = [[[2, 0], [3, 0], [3, 2], [1, 3], [1, 2]],  # Two polygons.
+                [[1, 4], [3, 4], [3, 3]]]
+    ContourSet(ax, [0, 1, 2], [filled01, filled12], filled=True, cmap=cmap)
+    ContourSet(ax, [1, 2], [lines0, lines1], linewidths=3, colors=['r', 'k'])
+
+    # Segments and kind codes (1 = MOVETO, 2 = LINETO, 79 = CLOSEPOLY).
+    segs = [[[4, 0], [7, 0], [7, 3], [4, 3], [4, 0],
+             [5, 1], [5, 2], [6, 2], [6, 1], [5, 1]]]
+    kinds = [[1, 2, 2, 2, 79, 1, 2, 2, 2, 79]]  # Polygon containing hole.
+    ContourSet(ax, [2, 3], [segs], [kinds], filled=True, cmap=cmap)
+    ContourSet(ax, [2], [segs], [kinds], colors='k', linewidths=3)
+
+
+@image_comparison(baseline_images=['contour_line_start_on_corner_edge'],
+                  extensions=['png'], remove_text=True)
+def test_contour_line_start_on_corner_edge():
+    fig, ax = plt.subplots(figsize=(6, 5))
+
+    x, y = np.meshgrid([0, 1, 2, 3, 4], [0, 1, 2])
+    z = 1.2 - (x - 2)**2 + (y - 1)**2
+    mask = np.zeros_like(z, dtype=bool)
+    mask[1, 1] = mask[1, 3] = True
+    z = np.ma.array(z, mask=mask)
+
+    filled = ax.contourf(x, y, z, corner_mask=True)
+    cbar = fig.colorbar(filled)
+    lines = ax.contour(x, y, z, corner_mask=True, colors='k')
+    cbar.add_lines(lines)

lib/matplotlib/tests/baseline_images/test_contour/contour_manual.png

@@ -1163,3 +1163,17 @@ def test_tricontour_non_finite_z():
     with pytest.raises(ValueError, match='z must not contain masked points '
                                          'within the triangulation'):
         plt.tricontourf(triang, np.ma.array([0, 1, 2, 3], mask=[1, 0, 0, 0]))
+
+
+def test_tricontourset_reuse():
+    # If TriContourSet returned from one tricontour(f) call is passed as first
+    # argument to another the underlying C++ contour generator will be reused.
+    x = [0.0, 0.5, 1.0]
+    y = [0.0, 1.0, 0.0]
+    z = [1.0, 2.0, 3.0]
+    fig, ax = plt.subplots()
+    tcs1 = ax.tricontourf(x, y, z)
+    tcs2 = ax.tricontour(x, y, z)
+    assert tcs2._contour_generator != tcs1._contour_generator
+    tcs3 = ax.tricontour(tcs1, z)
+    assert tcs3._contour_generator == tcs1._contour_generator

lib/matplotlib/tests/test_contour.py

@@ -36,6 +36,10 @@ def _process_args(self, *args, **kwargs):
             C = args[0]._contour_generator
             if self.levels is None:
                 self.levels = args[0].levels
+            self.zmin = args[0].zmin
+            self.zmax = args[0].zmax
+            self._mins = args[0]._mins
+            self._maxs = args[0]._maxs
         else:
             from matplotlib import _tri
             tri, z = self._contour_args(args, kwargs)