fix and test hoveron=fills for scatterternary

Author: alexcjohnson

src/traces/scatterternary/attributes.js

@@ -117,6 +117,7 @@ module.exports = {
     hoverinfo: extendFlat({}, plotAttrs.hoverinfo, {
         flags: ['a', 'b', 'c', 'text', 'name']
     }),
+    hoveron: scatterAttrs.hoveron,
     _nestedModules: {
         'marker.colorbar': 'Colorbar'
     }

src/traces/scatterternary/defaults.js

@@ -81,8 +81,11 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
         handleTextDefaults(traceIn, traceOut, layout, coerce);
     }
 
+    var dfltHoverOn = '';
+
     if(subTypes.hasMarkers(traceOut) || subTypes.hasText(traceOut)) {
         coerce('marker.maxdisplayed');
+        dfltHoverOn = 'points';
     }
 
     coerce('fill');
@@ -92,4 +95,9 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     }
 
     coerce('hoverinfo', (layout._dataLength === 1) ? 'a+b+c+text' : undefined);
+
+    if(!dfltHoverOn && (traceOut.fill === 'tonext' || traceOut.fill === 'toself')) {
+        dfltHoverOn = 'fills';
+    }
+    coerce('hoveron', dfltHoverOn || 'points');
 };

src/traces/scatterternary/hover.js

@@ -17,6 +17,10 @@ module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
     var scatterPointData = scatterHover(pointData, xval, yval, hovermode);
     if(!scatterPointData || scatterPointData[0].index === false) return;
 
+    // if hoveron='fills', we don't show any point data so the label is
+    // unchanged from what scatter gives us.
+    if(scatterPointData[0].index === undefined) return scatterPointData;
+
     var newPointData = scatterPointData[0],
         cdi = newPointData.cd[newPointData.index];
 

test/jasmine/tests/hover_label_test.js

@@ -690,4 +690,17 @@ describe('hover on fill', function() {
             return assertLabelsCorrect([155, 260], [160.325, 248.1], 'trace 0');
         }).then(done);
     });
+
+    it('should work for scatterternary too', function(done) {
+        var mock = require('@mocks/ternary_fill.json');
+        mock.data.forEach(function(trace) { trace.hoveron = 'fills'; });
+
+        Plotly.plot(createGraphDiv(), mock.data, mock.layout).then(function() {
+            return assertLabelsCorrect([245, 171], [249.7, 166], 'trace 2');
+        }).then(function() {
+            return assertLabelsCorrect([245, 226], [268.75, 265], 'trace 1');
+        }).then(function() {
+            return assertLabelsCorrect([245, 259], [249.7, 254], 'trace 0');
+        }).then(done);
+    });
 });