Fix: Use 404.html page in publish folder

In Netlify, you can set a custom 404 page by putting a 404.html file into the publish folder (e.g., public or whatever is specified in netlify.toml). Until now, this custom 404 page was not picked up by netlify dev. For it to work in netlify dev, the custom 404.html file had to be in the root folder. This commit makes the behavior of netlify dev consistent with Netlify in production by using the custom 404.html page in the publish folder. Fixes: #1158

Author: FinnWoelm

src/commands/dev/index.js

@@ -380,7 +380,7 @@ async function startDevServer(settings, log) {
  name: 'netlify-dev',
  port: settings.frameworkPort,
  templates: {
- notFound: '404.html',
+ notFound: path.join(settings.dist, '404.html'),
  },
  })
 

tests/command.dev.test.js

@@ -658,6 +658,31 @@ test('should return 404.html if exists for non existing routes', async t => {
  })
 })
 
+test('should return 404.html from publish folder if exists for non existing routes', async t => {
+ await withSiteBuilder('site-with-shadowing-404-in-publish-folder', async builder => {
+ builder
+ .withContentFile({
+ path: 'public/404.html',
+ content: '<h1>404 - My Custom 404 Page</h1>',
+ })
+ .withNetlifyToml({
+ config: {
+ build: {
+ publish: 'public/',
+ },
+ },
+ })
+
+ await builder.buildAsync()
+
+ await withDevServer({ cwd: builder.directory }, async server => {
+ const response = await fetch(`${server.url}/non-existent`)
+ t.is(response.status, 404)
+ t.is(await response.text(), '<h1>404 - My Custom 404 Page</h1>')
+ })
+ })
+})
+
 test('should return 404 for redirect', async t => {
  await withSiteBuilder('site-with-shadowing-404-redirect', async builder => {
  builder