fix: merge old and new noExternal: true correctly (#20502)

Author: hi-ogawa

packages/vite/src/node/__tests__/config.spec.ts

@@ -225,6 +225,42 @@ describe('mergeConfig', () => {
     expect(mergeConfig(newConfig, baseConfig)).toEqual(mergedConfig)
   })
 
+  test('merge ssr.noExternal and environments.ssr.resolve.noExternal', async () => {
+    const oldTrue = await resolveConfig(
+      {
+        ssr: {
+          noExternal: true,
+        },
+        environments: {
+          ssr: {
+            resolve: {
+              noExternal: ['dep'],
+            },
+          },
+        },
+      },
+      'serve',
+    )
+    expect(oldTrue.environments.ssr.resolve.noExternal).toEqual(true)
+
+    const newTrue = await resolveConfig(
+      {
+        ssr: {
+          noExternal: ['dep'],
+        },
+        environments: {
+          ssr: {
+            resolve: {
+              noExternal: true,
+            },
+          },
+        },
+      },
+      'serve',
+    )
+    expect(newTrue.environments.ssr.resolve.noExternal).toEqual(true)
+  })
+
   test('handles server.hmr.server', () => {
     const httpServer = http.createServer()
 

packages/vite/src/node/config.ts

@@ -1175,16 +1175,21 @@ export async function resolveConfig(
       configEnvironmentsSsr.optimizeDeps ?? {},
     )
 
+    // merge with `resolve` as the root to merge `noExternal` correctly
     configEnvironmentsSsr.resolve = mergeConfig(
       {
-        conditions: config.ssr?.resolve?.conditions,
-        externalConditions: config.ssr?.resolve?.externalConditions,
-        mainFields: config.ssr?.resolve?.mainFields,
-        external: config.ssr?.external,
-        noExternal: config.ssr?.noExternal,
-      } satisfies EnvironmentResolveOptions,
-      configEnvironmentsSsr.resolve ?? {},
-    )
+        resolve: {
+          conditions: config.ssr?.resolve?.conditions,
+          externalConditions: config.ssr?.resolve?.externalConditions,
+          mainFields: config.ssr?.resolve?.mainFields,
+          external: config.ssr?.external,
+          noExternal: config.ssr?.noExternal,
+        },
+      } satisfies EnvironmentOptions,
+      {
+        resolve: configEnvironmentsSsr.resolve ?? {},
+      },
+    ).resolve
   }
 
   if (config.build?.ssrEmitAssets !== undefined) {