checkSupport now static and protected

`checkSupport` of `GOVUKFrontend` can be overloaded by classes that extend it. Added tests for `createAll` when `checkSupport` has been overloaded.
alphagov · Sep 19, 2024 · 290af25 · 290af25
1 parent 3a651ba
commit 290af25
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Showing 2 changed files with 48 additions and 2 deletions.
diff --git a/packages/govuk-frontend/src/govuk/govuk-frontend-component.mjs b/packages/govuk-frontend/src/govuk/govuk-frontend-component.mjs
@@ -49,7 +49,8 @@ export class GOVUKFrontendComponent {
   /**
    * Validates whether components are supported
    *
-   * @private
+   * @protected
+   * @static
    * @throws {SupportError} when the components are not supported
    */
   checkSupport() {

diff --git a/packages/govuk-frontend/src/govuk/init.jsdom.test.mjs b/packages/govuk-frontend/src/govuk/init.jsdom.test.mjs
@@ -4,6 +4,7 @@ import {
 } from '@govuk-frontend/lib/names'
 
 import * as GOVUKFrontend from './all.mjs'
+import { GOVUKFrontendComponent } from './govuk-frontend-component.mjs'
 import { initAll, createAll } from './init.mjs'
 
 // Annoyingly these don't get hoisted if done in a loop
@@ -226,8 +227,9 @@ describe('createAll', () => {
     document.body.outerHTML = '<body></body>'
   })
 
-  class MockComponent {
+  class MockComponent extends GOVUKFrontendComponent {
     constructor(...args) {
+      super(...args)
       this.args = args
     }
 
@@ -292,6 +294,49 @@ describe('createAll', () => {
     )
   })
 
+  it('executes overloaded checkSupport of component', () => {
+    const componentRoot = document.createElement('div')
+    componentRoot.setAttribute('data-module', 'mock-component')
+    document.body.appendChild(componentRoot)
+
+    const checkSupportMock = jest.fn(() => {})
+
+    class MockComponentWithCheckSupport extends MockComponent {
+      checkSupport() {
+        checkSupportMock()
+      }
+    }
+
+    const result = createAll(MockComponentWithCheckSupport)
+
+    expect(checkSupportMock).toHaveBeenCalled()
+    expect(result).toStrictEqual([expect.any(MockComponent)])
+  })
+
+  it('returns empty array if overloaded checkSupport of component throws error', () => {
+    const componentRoot = document.createElement('div')
+    componentRoot.setAttribute('data-module', 'mock-component')
+    document.body.appendChild(componentRoot)
+
+    // Silence warnings in test output, and allow us to 'expect' them
+    jest.spyOn(global.console, 'log').mockImplementation()
+
+    const checkSupportMock = jest.fn(() => {
+      throw Error('Mock error')
+    })
+
+    class MockComponentWithCheckSupport extends MockComponent {
+      checkSupport() {
+        checkSupportMock()
+      }
+    }
+
+    const result = createAll(MockComponentWithCheckSupport)
+    expect(checkSupportMock).toHaveBeenCalled()
+    expect(result).toStrictEqual([])
+    expect(global.console.log).toHaveBeenCalledWith(expect.any(Error))
+  })
+
   it('returns an empty array if no matching components exist on the page', () => {
     const componentRoot = document.createElement('div')
     componentRoot.setAttribute(