Demotes H1 in markdown if required

designer/client/src/views/preview-components/declarationfield.njk

@@ -13,7 +13,7 @@
 
   <div class="govuk-form-group">
     <div class="{{ model.declaration.classes }}">
-      {{ model.declaration.text | markdown | safe }}
+      {{ model.declaration.text | markdown({ startingHeaderLevel: 2 }) | safe }}
     </div>
   </div>
 

model/src/form/form-editor/preview/markdown.js

@@ -31,15 +31,15 @@ export class Markdown extends Content {
   constructor(htmlElements, questionRenderer) {
     super(htmlElements, questionRenderer)
     const { content } = htmlElements.values
-    this._content = markdownToHtml(content)
+    this._content = markdownToHtml(content, { startingHeaderLevel: 2 })
   }
 
   /**
    * @param {string} value
    * @protected
    */
   _setContent(value) {
-    super._setContent(markdownToHtml(value))
+    super._setContent(markdownToHtml(value, { startingHeaderLevel: 2 }))
   }
 }
 

model/src/form/form-editor/preview/markdown.test.js

@@ -8,18 +8,20 @@ describe('markdown', () => {
   const questionElements = new ContentElements(
     buildMarkdownComponent({
       title: 'Which quest would you like to pick?',
-      content: '# This is a heading'
+      content: '# This is a heading demoted'
     })
   )
   describe('Markdown', () => {
     it('should create class', () => {
-      expect(questionElements.values.content).toBe('# This is a heading')
+      expect(questionElements.values.content).toBe(
+        '# This is a heading demoted'
+      )
       const res = new Markdown(questionElements, renderer)
       expect(res.renderInput).toEqual({
         id: 'markdown',
         name: 'markdown',
         classes: '',
-        content: '<h1>This is a heading</h1>\n'
+        content: '<h2>This is a heading demoted</h2>\n'
       })
       expect(res.titleText).toBe('Which quest would you like to pick?')
       expect(res.question).toBe('Which quest would you like to pick?')
@@ -40,7 +42,7 @@ describe('markdown', () => {
       res.optional = true
       expect(res.titleText).toBe('New question (optional)')
       res.content = '## This is a subheading'
-      expect(res.content).toBe('<h2>This is a subheading</h2>\n')
+      expect(res.content).toBe('<h3>This is a subheading</h3>\n')
     })
   })
 })

model/src/utils/markdown.test.js

@@ -45,7 +45,7 @@ describe('Helpers', () => {
         html: '<p><a class="govuk-link" href="mailto:dummy@defra.gov.uk">link</a></p>\n'
       }
     ])("formats '$markdown' to '$html'", ({ markdown, html }) => {
-      expect(markdownToHtml(markdown, exampleBaseUrl)).toBe(html)
+      expect(markdownToHtml(markdown, { baseUrl: exampleBaseUrl })).toBe(html)
     })
   })
 
@@ -63,4 +63,49 @@ describe('Helpers', () => {
       expect(markdownToHtml(markdown)).toBe(html)
     })
   })
+
+  describe('markdown with demotion from speific levels', () => {
+    it.each([
+      {
+        level: 1,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h1>This is H1</h1>\n<h2>This is H2</h2>\n<h3>This is H3</h3>\n<h4>This is H4</h4>\n<h5>This is H5</h5>\n<h6>This is H6</h6>\n'
+      },
+      {
+        level: 2,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h2>This is H1</h2>\n<h3>This is H2</h3>\n<h4>This is H3</h4>\n<h5>This is H4</h5>\n<h6>This is H5</h6>\n<h6>This is H6</h6>\n'
+      },
+      {
+        level: 3,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h3>This is H1</h3>\n<h4>This is H2</h4>\n<h5>This is H3</h5>\n<h6>This is H4</h6>\n<h6>This is H5</h6>\n<h6>This is H6</h6>\n'
+      },
+      {
+        level: 4,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h4>This is H1</h4>\n<h5>This is H2</h5>\n<h6>This is H3</h6>\n<h6>This is H4</h6>\n<h6>This is H5</h6>\n<h6>This is H6</h6>\n'
+      },
+      {
+        level: 5,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h5>This is H1</h5>\n<h6>This is H2</h6>\n<h6>This is H3</h6>\n<h6>This is H4</h6>\n<h6>This is H5</h6>\n<h6>This is H6</h6>\n'
+      },
+      {
+        level: 6,
+        markdown:
+          '# This is H1\n## This is H2\n### This is H3\n#### This is H4\n##### This is H5\n###### This is H6\n',
+        html: '<h6>This is H1</h6>\n<h6>This is H2</h6>\n<h6>This is H3</h6>\n<h6>This is H4</h6>\n<h6>This is H5</h6>\n<h6>This is H6</h6>\n'
+      }
+    ])("formats '$markdown' to '$html'", ({ markdown, html, level }) => {
+      expect(markdownToHtml(markdown, { startingHeaderLevel: level })).toBe(
+        html
+      )
+    })
+  })
 })

model/src/utils/markdown.ts

@@ -26,12 +26,26 @@ function renderLink(href: string, text: string, baseUrl?: string) {
   return `<a ${attrs.join(' ')}>${label}</a>`
 }
 
+function demoteHeading(
+  text: string,
+  depth: number,
+  startingHeaderLevel: number
+) {
+  // Max heading is h6 so don't demote further than that
+  depth = Math.min(depth + startingHeaderLevel - 1, 6)
+  return `<h${depth}>${text}</h${depth}>
+`
+}
+
 /**
  * Convert markdown to HTML, escaping any HTML tags first
  */
 export function markdownToHtml(
   markdown: string | null | undefined,
-  baseUrl?: string // optional in some contexts, e.g. from the designer where it might not make sense
+  options?: {
+    baseUrl?: string // optional in some contexts, e.g. from the designer where it might not make sense,
+    startingHeaderLevel?: number
+  }
 ) {
   if (markdown === undefined || markdown === null) {
     return ''
@@ -46,8 +60,12 @@ export function markdownToHtml(
 
   const renderer = new Renderer()
   renderer.link = ({ href, text }: Tokens.Link): string => {
-    return renderLink(href, text, baseUrl)
+    return renderLink(href, text, options?.baseUrl)
+  }
+  if (options?.startingHeaderLevel) {
+    renderer.heading = ({ text, depth }: Tokens.Heading): string => {
+      return demoteHeading(text, depth, options.startingHeaderLevel ?? 1)
+    }
   }
-
   return marked.parse(escaped, { async: false, renderer })
 }