feat(plugin-manifest): support SVG favicon (#25276)

Co-authored-by: Yogi <me@yogi.codes>

packages/gatsby-plugin-manifest/README.md

@@ -238,7 +238,7 @@ module.exports = {
 
 #### Disable favicon
 
-A favicon is generated by default in automatic and hybrid modes (a 32x32 PNG, included via a `<link rel="icon" />` tag in the document head).
+A favicon is generated by default in automatic and hybrid modes (a 32x32 PNG, included via a `<link rel="icon" />` tag in the document head). Additionally, if an SVG icon is provided as the source, it will be used in the document head without modification as a favicon. The PNG will still be created and included as a fallback. Including the SVG icon allows creating a responsive icon with CSS Media Queries such as [dark mode](https://catalin.red/svg-favicon-light-dark-theme/#browser-support-and-fallbacks) and [others](https://css-tricks.com/svg-favicons-and-all-the-fun-things-we-can-do-with-them/#other-media-queries).
 
 You can set the `include_favicon` plugin option to `false` to opt-out of this behavior.
 

packages/gatsby-plugin-manifest/src/__tests__/__snapshots__/gatsby-ssr.js.snap

@@ -31,9 +31,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Cache Busting Does file name cache busting if "cache_busting_mode" option is set to name 1`] = `
 Array [
+  <link
+    href="/favicon-00913339321ee5a854812aea11f8a5d4.svg"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32-00913339321ee5a854812aea11f8a5d4.png"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"
@@ -84,9 +90,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Cache Busting Does query cache busting if "cache_busting_mode" option is set to query 1`] = `
 Array [
+  <link
+    href="/favicon.svg?v=00913339321ee5a854812aea11f8a5d4"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32.png?v=00913339321ee5a854812aea11f8a5d4"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"
@@ -137,9 +149,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Cache Busting Does query cache busting if "cache_busting_mode" option is set to undefined 1`] = `
 Array [
+  <link
+    href="/favicon.svg?v=00913339321ee5a854812aea11f8a5d4"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32.png?v=00913339321ee5a854812aea11f8a5d4"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"
@@ -190,9 +208,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Cache Busting doesn't add cache busting if "cache_busting_mode" option is set to none 1`] = `
 Array [
+  <link
+    href="/favicon.svg"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32.png"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"
@@ -262,9 +286,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Favicon Adds link favicon tag if "include_favicon" is set to true 1`] = `
 Array [
+  <link
+    href="/favicon.svg"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32.png"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"
@@ -424,9 +454,15 @@ Array [
 
 exports[`gatsby-plugin-manifest Manifest Link Generation Adds "icon" and "manifest" links and "theme_color" meta tag to head 1`] = `
 Array [
+  <link
+    href="/favicon.svg?v=00913339321ee5a854812aea11f8a5d4"
+    rel="icon"
+    type="image/svg+xml"
+  />,
   <link
     href="/favicon-32x32.png?v=00913339321ee5a854812aea11f8a5d4"
     rel="icon"
+    type="image/png"
   />,
   <link
     href="/manifest.webmanifest"

packages/gatsby-plugin-manifest/src/__tests__/gatsby-node.js

@@ -4,6 +4,7 @@ jest.mock(`fs`, () => {
     writeFileSync: jest.fn(),
     mkdirSync: jest.fn(),
     readFileSync: jest.fn().mockImplementation(() => `someIconImage`),
+    copyFileSync: jest.fn(),
     statSync: jest.fn(),
   }
 })
@@ -27,6 +28,7 @@ jest.mock(`sharp`, () => {
           return {
             width: 128,
             height: 128,
+            format: `png`,
           }
         }
       })()
@@ -98,6 +100,7 @@ describe(`Test plugin manifest options`, () => {
     fs.writeFileSync.mockReset()
     fs.mkdirSync.mockReset()
     fs.existsSync.mockReset()
+    fs.copyFileSync.mockReset()
     sharp.mockClear()
   })
 
@@ -225,6 +228,7 @@ describe(`Test plugin manifest options`, () => {
     // disabled by the `include_favicon` option.
     expect(sharp).toHaveBeenCalledTimes(2)
     expect(sharp).toHaveBeenCalledWith(icon, { density: size })
+    expect(fs.copyFileSync).toHaveBeenCalledTimes(0)
   })
 
   it(`fails on non existing icon`, async () => {
@@ -485,4 +489,37 @@ describe(`Test plugin manifest options`, () => {
       JSON.stringify(expectedResults[2])
     )
   })
+
+  it(`writes SVG to public if src icon is SVG`, async () => {
+    sharp.mockReturnValueOnce({
+      metadata: () => {
+        return { format: `svg` }
+      },
+    })
+    const icon = `this/is/an/icon.svg`
+    const specificOptions = {
+      ...manifestOptions,
+      icon: icon,
+    }
+
+    await onPostBootstrap({ ...apiArgs }, specificOptions)
+
+    expect(fs.copyFileSync).toHaveBeenCalledWith(
+      expect.stringContaining(`icon.svg`),
+      expect.stringContaining(`favicon.svg`)
+    )
+
+    expect(fs.copyFileSync).toHaveBeenCalledTimes(1)
+  })
+
+  it(`does not write SVG to public if src icon is PNG`, async () => {
+    const specificOptions = {
+      ...manifestOptions,
+      icon: `this/is/an/icon.png`,
+    }
+
+    await onPostBootstrap({ ...apiArgs }, specificOptions)
+
+    expect(fs.copyFileSync).toHaveBeenCalledTimes(0)
+  })
 })

packages/gatsby-plugin-manifest/src/__tests__/gatsby-ssr.js

@@ -15,7 +15,8 @@ const onRenderBody = (args, pluginOptions) => {
 let headComponents
 const setHeadComponents = args => (headComponents = headComponents.concat(args))
 
-const defaultIcon = `pretend/this/exists.png`
+const defaultIcon = `pretend/this/exists.svg`
+
 const ssrArgs = {
   setHeadComponents,
   pathname: `/`,
@@ -276,7 +277,7 @@ describe(`gatsby-plugin-manifest`, () => {
     })
 
     it(`Does query cache busting if "cache_busting_mode" option is set to undefined`, () => {
-      onRenderBody(ssrArgs, { icon: true })
+      onRenderBody(ssrArgs, { icon: defaultIcon })
       expect(headComponents).toMatchSnapshot()
     })
   })
@@ -285,7 +286,7 @@ describe(`gatsby-plugin-manifest`, () => {
     it(`Adds link favicon tag if "include_favicon" is set to true`, () => {
       onRenderBody(ssrArgs, {
         icon: defaultIcon,
-        include_favicon: defaultIcon,
+        include_favicon: true,
         legacy: false,
         cache_busting_mode: `none`,
       })

packages/gatsby-plugin-manifest/src/gatsby-node.js

@@ -253,6 +253,10 @@ const makeManifest = async ({
     // the resized image(s)
     if (faviconIsEnabled) {
       await processIconSet(favicons)
+
+      if (metadata.format === `svg`) {
+        fs.copyFileSync(icon, path.join(`public`, `favicon.svg`))
+      }
     }
   }
 

packages/gatsby-plugin-manifest/src/gatsby-ssr.js

@@ -31,14 +31,27 @@ exports.onRenderBody = (
   // If icons were generated, also add a favicon link.
   if (srcIconExists) {
     if (insertFaviconLinkTag) {
+      if (icon?.endsWith(`.svg`)) {
+        headComponents.push(
+          <link
+            key={`gatsby-plugin-manifest-icon-link-svg`}
+            rel="icon"
+            href={withPrefix(
+              addDigestToPath(`favicon.svg`, cacheDigest, cacheBusting)
+            )}
+            type="image/svg+xml"
+          />
+        )
+      }
       favicons.forEach(favicon => {
         headComponents.push(
           <link
-            key={`gatsby-plugin-manifest-icon-link`}
+            key={`gatsby-plugin-manifest-icon-link-png`}
             rel="icon"
             href={withPrefix(
               addDigestToPath(favicon.src, cacheDigest, cacheBusting)
             )}
+            type="image/png"
           />
         )
       })