Add tests for current page filter

test/lib/filters/current-page.js

@@ -0,0 +1,37 @@
+const assert = require('assert/strict')
+const { describe, it } = require('node:test')
+const currentPage = require('../../../lib/filters/current-page.js')
+
+const navigationData = [
+  { text: 'Home', href: '/' },
+  { text: 'Styles', href: '/styles' }
+]
+
+describe('currentPage filter', () => {
+  it('Indicates the home page is current', () => {
+    const result = currentPage(navigationData, '/')
+
+    assert.deepEqual(result, [
+      { text: 'Home', href: '/', current: true },
+      { text: 'Styles', href: '/styles', current: false }
+    ])
+  })
+
+  it('Indicates the section page is current', () => {
+    const result = currentPage(navigationData, '/styles')
+
+    assert.deepEqual(result, [
+      { text: 'Home', href: '/', current: false },
+      { text: 'Styles', href: '/styles', current: true }
+    ])
+  })
+
+  it('Indicates the section sub page is current', () => {
+    const result = currentPage(navigationData, '/styles/colour')
+
+    assert.deepEqual(result, [
+      { text: 'Home', href: '/', current: false },
+      { text: 'Styles', href: '/styles', current: true }
+    ])
+  })
+})