Fix/scatter tooltip mode (#8354)

* scatter tooltip should be point by default
* edited mode on better level and updated docs to be bit more clear

docs/docs/charts/line.mdx

@@ -87,7 +87,7 @@ The line chart allows a number of properties to be specified for each dataset. T
 | [`pointRadius`](#point-styling) | `number` | Yes | Yes | `3`
 | [`pointRotation`](#point-styling) | `number` | Yes | Yes | `0`
 | [`pointStyle`](#point-styling) | `string`\|`Image` | Yes | Yes | `'circle'`
-| [`showLine`](#line-styling) | `boolean` | - | - | `undefined`
+| [`showLine`](#line-styling) | `boolean` | - | - | `true`
 | [`spanGaps`](#line-styling) | `boolean`\|`number` | - | - | `undefined`
 | [`stepped`](#stepped) | `boolean`\|`string` | - | - | `false`
 | [`xAxisID`](#general) | `string` | - | - | first x axis

docs/docs/charts/scatter.mdx

@@ -50,6 +50,7 @@ function example() {
 ## Dataset Properties
 
 The scatter chart supports all of the same properties as the [line chart](./charts/line.mdx#dataset-properties).
+By default, the scatter chart will override the showLine property of the line chart to `false`.
 
 ## Data Structure
 

src/controllers/controller.scatter.js

@@ -24,6 +24,10 @@ ScatterController.defaults = {
 		fill: false
 	},
 
+	interaction: {
+		mode: 'point'
+	},
+
 	plugins: {
 		tooltip: {
 			callbacks: {

test/specs/controller.scatter.tests.js

@@ -31,4 +31,44 @@ describe('Chart.controllers.scatter', function() {
 
 		jasmine.triggerMouseEvent(chart, 'mousemove', point);
 	});
+
+	it('should only show a single point in the tooltip on multiple datasets', function(done) {
+		var chart = window.acquireChart({
+			type: 'scatter',
+			data: {
+				datasets: [{
+					data: [{
+						x: 10,
+						y: 15
+					},
+					{
+						x: 12,
+						y: 10
+					}],
+					label: 'dataset1'
+				},
+				{
+					data: [{
+						x: 20,
+						y: 10
+					},
+					{
+						x: 4,
+						y: 8
+					}],
+					label: 'dataset2'
+				}]
+			},
+			options: {}
+		});
+		var point = chart.getDatasetMeta(0).data[1];
+
+		afterEvent(chart, 'mousemove', function() {
+			expect(chart.tooltip.body.length).toEqual(1);
+
+			done();
+		});
+
+		jasmine.triggerMouseEvent(chart, 'mousemove', point);
+	});
 });