fix(vitest): auto-enable "github-actions" only where users didn't configure reporters (#5158)

Author: hi-ogawa

docs/guide/reporters.md

@@ -447,7 +447,17 @@ export default defineConfig({
 ### Github Actions Reporter <Badge type="info">1.3.0+</Badge>
 
 Output [workflow commands](https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-error-message)
-to provide annotations for test failures. This reporter is automatically enabled when `process.env.GITHUB_ACTIONS === 'true'`, thus it doesn't require any configuration.
+to provide annotations for test failures. This reporter is automatically enabled with a [`default`](#default-reporter) reporter when `process.env.GITHUB_ACTIONS === 'true'`.
+
+If you configure non-default reporters, you need to explicitly add `github-actions`.
+
+```ts
+export default defineConfig({
+  test: {
+    reporters: process.env.GITHUB_ACTIONS ? ['dot', 'github-actions'] : ['dot'],
+  },
+})
+```
 
 <img alt="Github Actions" img-dark src="https://github.com/vitest-dev/vitest/assets/4232207/336cddc2-df6b-4b8a-8e72-4d00010e37f5">
 <img alt="Github Actions" img-light src="https://github.com/vitest-dev/vitest/assets/4232207/ce8447c1-0eab-4fe1-abef-d0d322290dca">

packages/vitest/src/node/config.ts

@@ -419,12 +419,13 @@ export function resolveConfig(
       resolved.reporters = Array.from(new Set(toArray(cliReporters))).filter(Boolean).map(reporter => [reporter, {}])
   }
 
-  if (!resolved.reporters.length)
+  if (!resolved.reporters.length) {
     resolved.reporters.push(['default', {}])
 
-  // automatically enable github-actions reporter
-  if (process.env.GITHUB_ACTIONS === 'true' && !resolved.reporters.some(v => Array.isArray(v) && v[0] === 'github-actions'))
-    resolved.reporters.push(['github-actions', {}])
+    // also enable github-actions reporter as a default
+    if (process.env.GITHUB_ACTIONS === 'true')
+      resolved.reporters.push(['github-actions', {}])
+  }
 
   if (resolved.changed)
     resolved.passWithNoTests ??= true