test(xychart): add more TooltipProvider tests

packages/visx-xychart/test/providers/TooltipProvider.test.tsx

@@ -1,18 +1,70 @@
-import React, { useContext } from 'react';
+import React, { useContext, useEffect } from 'react';
 import { mount } from 'enzyme';
-import { TooltipProvider, TooltipContext } from '../../src';
+import { TooltipProvider, TooltipContext, TooltipData } from '../../src';
 
 describe('<TooltipProvider />', () => {
   it('should be defined', () => {
     expect(TooltipProvider).toBeDefined();
   });
 
-  it('should provide an emitter for subscribing and emitting events', () => {
+  it('should provide tooltip state', () => {
     expect.assertions(1);
 
     const TooltipConsumer = () => {
       const tooltipContext = useContext(TooltipContext);
-      expect(tooltipContext).toBeDefined();
+      expect(tooltipContext).toMatchObject({
+        tooltipOpen: expect.any(Boolean),
+        showTooltip: expect.any(Function),
+        updateTooltip: expect.any(Function),
+        hideTooltip: expect.any(Function),
+      });
+
+      return null;
+    };
+
+    mount(
+      <TooltipProvider>
+        <TooltipConsumer />
+      </TooltipProvider>,
+    );
+  });
+
+  it('showTooltip should update tooltipData.nearestDatum/datumByKey', () => {
+    expect.assertions(1);
+
+    const TooltipConsumer = () => {
+      const tooltipContext = useContext(TooltipContext);
+      const tooltipOpen = tooltipContext?.tooltipOpen;
+      const showTooltip = tooltipContext?.showTooltip;
+
+      useEffect(() => {
+        // this triggers a re-render of the component which triggers the assertion block
+        if (!tooltipOpen && showTooltip) {
+          showTooltip({
+            key: 'near',
+            index: 0,
+            distanceX: 0,
+            distanceY: 0,
+            datum: { hi: 'hello' },
+          });
+          showTooltip({
+            key: 'far',
+            index: 1,
+            datum: { good: 'bye' },
+            // no distance = Infinity
+          });
+        }
+      }, [tooltipOpen, showTooltip]);
+
+      if (tooltipOpen) {
+        expect(tooltipContext?.tooltipData).toMatchObject({
+          nearestDatum: { key: 'near', index: 0, distance: 0, datum: { hi: 'hello' } },
+          datumByKey: {
+            near: { key: 'near', index: 0, datum: { hi: 'hello' } },
+            far: { key: 'far', index: 1, datum: { good: 'bye' } },
+          },
+        } as TooltipData<object>);
+      }
 
       return null;
     };