test: css supports

src/test/utils.spec.js

@@ -1,4 +1,4 @@
-import { debounce, computeTooltipPosition, cssTimeToMs } from 'utils'
+import { debounce, computeTooltipPosition, cssTimeToMs, cssSupports } from 'utils'
 
 // Tell Jest to mock all timeout functions
 jest.useRealTimers()
@@ -134,6 +134,35 @@ describe('debounce', () => {
   })
 })
 
+describe('css supports', () => {
+  let windowSpy
+
+  beforeEach(() => {
+    windowSpy = jest.spyOn(window, 'window', 'get')
+  })
+
+  afterEach(() => {
+    windowSpy.mockRestore()
+  })
+
+  test('returns true if css property is supported', () => {
+    expect(cssSupports('position', 'relative')).toBe(true)
+  })
+
+  test('returns false if css property is not supported', () => {
+    expect(cssSupports('position', 'foo')).toBe(false)
+  })
+
+  test('returns true if `window.CSS.supports` is not available', () => {
+    windowSpy.mockImplementation(() => ({
+      CSS: {
+        supports: undefined,
+      },
+    }))
+    expect(cssSupports('position', 'foo')).toBe(true)
+  })
+})
+
 describe('css time to ms', () => {
   test('converts time correctly', () => {
     expect(cssTimeToMs('1s')).toBe(1000)