Allow passing classes for table row headers

src/components/table/template.njk

@@ -22,7 +22,7 @@
     <tr class="govuk-table__row">
     {% for cell in row %}
       {% if loop.first and params.firstCellIsHeader %}
-      <th class="govuk-table__header" scope="row">{{ cell.html | safe if cell.html else cell.text }}</th>
+      <th class="govuk-table__header{%- if cell.classes %} {{ cell.classes }}{% endif %}" scope="row">{{ cell.html | safe if cell.html else cell.text }}</th>
       {% else %}
       <td class="govuk-table__cell
       {%- if cell.format %} govuk-table__cell--{{ cell.format }}{% endif %}

src/components/table/template.test.js

@@ -109,6 +109,26 @@ describe('Table', () => {
     expect($lastTableHeader.hasClass('govuk-table__header')).toBeTruthy()
   })
 
+  it('includes additional classes when the first row is a header', () => {
+    const $ = render('table', {
+      'firstCellIsHeader': true,
+      'rows': [
+        [
+          {
+            'text': 'January',
+            'classes': 'my-custom-class'
+          },
+          {
+            'text': '£85',
+            'format': 'numeric'
+          }
+        ]
+      ]
+    })
+
+    expect($('.govuk-table__row *:first-child').hasClass('my-custom-class')).toBeTruthy()
+  })
+
   it('renders with thead', () => {
     const args = examples['table with head']
     const $ = render('table', args)