[cli] Add test for readme.md with now.json and vercel.json (#4357)

This PR adds a E2E test to make sure #4042 works correctly.

packages/now-cli/test/helpers/prepare.js

@@ -299,6 +299,14 @@ CMD ["node", "index.js"]`,
         redirects: [{ source: `/(.*)`, destination: 'https://example.com/$1' }],
       }),
     },
+    'deploy-with-only-readme-now-json': {
+      'now.json': JSON.stringify({ version: 2 }),
+      'README.md': 'readme contents',
+    },
+    'deploy-with-only-readme-vercel-json': {
+      'vercel.json': JSON.stringify({ version: 2 }),
+      'README.md': 'readme contents',
+    },
     'local-config-v2': {
       [`main-${session}.html`]: '<h1>hello main</h1>',
       [`test-${session}.html`]: '<h1>hello test</h1>',

packages/now-cli/test/integration.js

@@ -2823,3 +2823,41 @@ test('whoami with local .vercel scope', async t => {
   // clean up
   await remove(path.join(directory, '.vercel'));
 });
+
+test('deploys with only now.json and README.md', async t => {
+  const directory = fixture('deploy-with-only-readme-now-json');
+
+  const { exitCode, stderr, stdout } = await execa(
+    binaryPath,
+    [...defaultArgs, '--confirm'],
+    {
+      cwd: directory,
+      reject: false,
+    }
+  );
+
+  t.is(exitCode, 0, formatOutput({ stderr, stdout }));
+  const { host } = new URL(stdout);
+  const res = await fetch(`https://${host}/README.md`);
+  const text = await res.text();
+  t.regex(text, /readme contents/);
+});
+
+test('deploys with only vercel.json and README.md', async t => {
+  const directory = fixture('deploy-with-only-readme-vercel-json');
+
+  const { exitCode, stderr, stdout } = await execa(
+    binaryPath,
+    [...defaultArgs, '--confirm'],
+    {
+      cwd: directory,
+      reject: false,
+    }
+  );
+
+  t.is(exitCode, 0, formatOutput({ stderr, stdout }));
+  const { host } = new URL(stdout);
+  const res = await fetch(`https://${host}/README.md`);
+  const text = await res.text();
+  t.regex(text, /readme contents/);
+});