test: add two more range slider mocks

Author: etpinard

test/image/baselines/range_slider_axes_double.png

@@ -0,0 +1,60 @@
+{
+  "data": [
+    {
+      "x": [
+        1,
+        2,
+        3
+      ],
+      "y": [
+        40,
+        50,
+        60
+      ],
+      "name": "yaxis data",
+      "type": "scatter"
+    },
+    {
+      "x": [
+        2,
+        3,
+        null,
+        4,
+        5
+      ],
+      "y": [
+        4,
+        5,
+        null,
+        7,
+        8
+      ],
+      "name": "yaxis2 data",
+      "yaxis": "y2",
+      "type": "scatter"
+    }
+  ],
+  "layout": {
+    "title": "Double Y Axis Example",
+    "xaxis": {
+      "title": "Wavelength (nm)",
+      "rangeslider": {
+        "thickness": 0.2
+      }
+    },
+    "yaxis": {
+      "title": "yaxis title"
+    },
+    "yaxis2": {
+      "title": "yaxis2 title",
+      "titlefont": {
+        "color": "rgb(148, 103, 189)"
+      },
+      "tickfont": {
+        "color": "rgb(148, 103, 189)"
+      },
+      "side": "right",
+      "overlaying": "y"
+    }
+  }
+}