Add a test for array-like intensity

Author: core-man

pygmt/tests/test_plot.py

@@ -231,6 +231,42 @@ def test_plot_colors_sizes_proj(data, region):
     return fig
 
 
+@check_figures_equal()
+def test_plot_varying_intensity():
+    """
+    Plot the data with array-like intensity.
+    """
+    x = np.arange(1, 10)
+    y = np.arange(1, 10)
+    intensity = np.linspace(-1, 1, len(x))
+
+    fig_ref, fig_test = Figure(), Figure()
+    # Use single-character arguments for the reference image
+    with GMTTempFile() as tmpfile:
+        np.savetxt(tmpfile.name, np.c_[x, y, intensity], fmt="%s")
+        fig_ref.plot(
+            data=tmpfile.name,
+            R="0/10/0/10",
+            J="X4i",
+            B="",
+            S="c0.2c",
+            G="blue",
+            I="",
+        )
+
+    fig_test.plot(
+        x=x,
+        y=y,
+        region=[0, 10, 0, 10],
+        projection="X4i",
+        frame=True,
+        style="c0.2c",
+        color="blue",
+        intensity=intensity,
+    )
+    return fig_ref, fig_test
+
+
 @check_figures_equal()
 def test_plot_transparency():
     """