Merge pull request #214 from github/clean-up-register-tests

Author: keithamus

src/register.ts

@@ -8,7 +8,7 @@ import {dasherize} from './dasherize.js'
  *
  * Example: HelloController => hello-controller
  */
-export function register(classObject: CustomElement): void {
+export function register(classObject: CustomElement): CustomElement {
   const name = dasherize(classObject.name).replace(/-element$/, '')
 
   try {
@@ -19,8 +19,7 @@ export function register(classObject: CustomElement): void {
   } catch (e: unknown) {
     // The only reason for window.customElements.define to throw a `NotSupportedError`
     // is if the element has already been defined.
-    if (e instanceof DOMException && e.name === 'NotSupportedError') return
-
-    throw e
+    if (!(e instanceof DOMException && e.name === 'NotSupportedError')) throw e
   }
+  return classObject
 }

test/register.ts

@@ -1,49 +1,73 @@
 import {expect} from '@open-wc/testing'
+import {restore, replace, fake} from 'sinon'
 import {register} from '../src/register.js'
 
 describe('register', () => {
+  afterEach(() => {
+    restore()
+  })
+
   it('registers the class as a custom element, normalising the class name', () => {
-    class MyFirstController {}
-    register(MyFirstController)
-    expect(window.customElements.get('my-first-controller')).to.equal(MyFirstController)
+    @register
+    class MyFirstClass {}
+    expect(window.customElements.get('my-first-class')).to.equal(MyFirstClass)
   })
 
   it('does not register controllers that already exist', () => {
     {
-      class MySecondController {}
-      register(MySecondController)
-      expect(window.customElements.get('my-second-controller')).to.equal(MySecondController)
+      @register
+      class MySecondClass {}
+      expect(window.customElements.get('my-second-class')).to.equal(MySecondClass)
+    }
+    {
+      @register
+      class MySecondClass {}
+      expect(window.customElements.get('my-second-class')).to.not.equal(MySecondClass)
     }
+  })
+
+  it('will redefine controllers, catching on errors', () => {
+    replace(customElements, 'define', fake())
+    replace(
+      customElements,
+      'get',
+      fake(() => class {})
+    )
     {
-      class MySecondController {}
-      register(MySecondController)
-      expect(window.customElements.get('my-second-controller')).to.not.equal(MySecondController)
+      @register
+      class MyThirdClass {}
+      expect(customElements.define).to.be.calledOnceWithExactly('my-third-class', MyThirdClass)
     }
+    expect(() => {
+      @register
+      class MyThirdClass {}
+      expect(customElements.define).to.be.calledOnceWithExactly('my-third-class', MyThirdClass)
+    }).to.throw(Error)
   })
 
   it('dasherises class names', () => {
+    @register
     class ThisIsAnExampleOfDasherisedClassNames {}
-    register(ThisIsAnExampleOfDasherisedClassNames)
     expect(window.customElements.get('this-is-an-example-of-dasherised-class-names')).to.equal(
       ThisIsAnExampleOfDasherisedClassNames
     )
   })
 
   it('will intuitively dasherize acryonyms', () => {
+    @register
     class URLBar {}
-    register(URLBar)
     expect(window.customElements.get('url-bar')).to.equal(URLBar)
   })
 
   it('dasherizes cap suffixed names correctly', () => {
+    @register
     class ClipX {}
-    register(ClipX)
     expect(window.customElements.get('clip-x')).to.equal(ClipX)
   })
 
   it('automatically drops the `Element` suffix', () => {
-    class AutoCompleteElement {}
-    register(AutoCompleteElement)
-    expect(window.customElements.get('auto-complete')).to.equal(AutoCompleteElement)
+    @register
+    class FirstSuffixElement {}
+    expect(window.customElements.get('first-suffix')).to.equal(FirstSuffixElement)
   })
 })