fixed doFill; added tests

Author: FabTechAT

test/fixtures/plugin.filler/line/above-below-vertical-linechart.js

@@ -0,0 +1,46 @@
+module.exports = {
+  config: {
+    type: 'line',
+    data: {
+      labels: [1, 2, 3, 4],
+      datasets: [
+        {
+          data: [200, 400, 200, 400],
+          cubicInterpolationMode: 'monotone',
+          tension: 0.4,
+          spanGaps: true,
+          borderColor: 'blue',
+          pointRadius: 0,
+          fill: {
+            target: 1,
+            below: 'rgba(255, 0, 0, 0.4)',
+            above: 'rgba(53, 221, 53, 0.4)',
+          }
+        },
+        {
+          data: [400, 200, 400, 200],
+          cubicInterpolationMode: 'monotone',
+          tension: 0.4,
+          spanGaps: true,
+          borderColor: 'orange',
+          pointRadius: 0,
+        },
+      ]
+    },
+    options: {
+      indexAxis: 'y',
+      // maintainAspectRatio: false,
+      plugins: {
+        filler: {
+          propagate: false
+        },
+        datalabels: {
+          display: false
+        },
+        legend: {
+          display: false
+        },
+      }
+    }
+  }
+};