Initialise accordion correctly when all sections are expanded

The button would still read 'Open all'

src/Assets/Javascript/__snapshots__/accordion.test.js.snap

@@ -15,6 +15,21 @@ exports[`Accordion module init() when all sections are closed initialises accord
 "
 `;
 
+exports[`Accordion module init() when all sections are open initialises accordion HTML correctly 1`] = `
+"
+<div data-module=\\"accordion\\" class=\\"with-js\\"><div class=\\"accordion-controls\\"><button class=\\"accordion-expand-all\\" aria-expanded=\\"true\\" type=\\"button\\">Close all</button></div>
+  <div class=\\"accordion-section\\" aria-expanded=\\"true\\">
+    <div class=\\"accordion-section-header\\" tabindex=\\"0\\" role=\\"button\\">Header 1<span class=\\"icon\\"></span></div>
+    <div class=\\"accordion-section-body\\">Body 1</div>
+  </div>
+  <div class=\\"accordion-section\\" aria-expanded=\\"true\\">
+    <div class=\\"accordion-section-header\\" tabindex=\\"0\\" role=\\"button\\">Header 2<span class=\\"icon\\"></span></div>
+    <div class=\\"accordion-section-body\\">Body 2</div>
+  </div>
+</div>
+"
+`;
+
 exports[`Accordion module init() when in an incompatible environment leaves HTML untouched 1`] = `
 "
 <div data-module=\\"accordion\\">

src/Assets/Javascript/accordion.js

@@ -23,6 +23,7 @@ Accordion.prototype.init = function () {
     accordion_controls.appendChild(open_or_close_all_button)
     this.$module.insertBefore(accordion_controls, this.$module.firstChild)
     this.$module.classList.add('with-js')
+    this.updateOpenAll()
   }
 }
 

src/Assets/Javascript/accordion.test.js

@@ -61,6 +61,20 @@ describe("Accordion module", () => {
         expect(document.body.innerHTML).toMatchSnapshot()
       })
     })
+
+    describe("when all sections are open", () => {
+      beforeEach(() => {
+        document
+          .querySelectorAll(".accordion-section")
+          .forEach($section => $section.classList.add("accordion-section--expanded"))
+        accordion.init()
+      })
+
+      it("initialises accordion HTML correctly", () => {
+        expect(document.querySelector(".accordion-expand-all").innerHTML).toBe("Close all")
+        expect(document.body.innerHTML).toMatchSnapshot()
+      })
+    })
   })
 
   describe("events", () => {