Add test for RTL legend hitboxes

test/fixtures/plugin.legend/horizontal-rtl-hitbox.js

@@ -0,0 +1,52 @@
+module.exports = {
+  description: 'https://github.com/chartjs/Chart.js/issues/9278',
+  config: {
+    type: 'pie',
+    data: {
+      labels: ['aaa', 'bb', 'c'],
+      datasets: [{
+        data: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
+        backgroundColor: 'red'
+      }]
+    },
+    options: {
+      plugins: {
+        legend: {
+          position: 'top',
+          rtl: 'true',
+        }
+      },
+      layout: {
+        padding: {
+          top: 50,
+          left: 30,
+          right: 30,
+          bottom: 50
+        }
+      }
+    },
+    plugins: [{
+      id: 'legend-hit-box',
+      afterDraw(chart) {
+        const ctx = chart.ctx;
+        ctx.save();
+        ctx.strokeStyle = 'green';
+        ctx.lineWidth = 1;
+
+        const legend = chart.legend;
+        legend.legendHitBoxes.forEach(box => {
+          ctx.strokeRect(box.left, box.top, box.width, box.height);
+        });
+
+        ctx.restore();
+      }
+    }]
+  },
+  options: {
+    spriteText: true,
+    canvas: {
+      width: 400,
+      height: 300
+    },
+  }
+};