fix: re-apply default conditions if using vite 6 or later

packages/vitest/src/node/plugins/conditions.ts

@@ -0,0 +1,16 @@
+import * as vite from 'vite'
+
+type Vite6Options = typeof vite & Partial<{
+  defaultServerConditions?: string[]
+}>
+
+/**
+ * In Vite 6+, providing a value for resolve.conditions overrides the defaults
+ * In Vite 5, passing ["node"] will be merged with the defaults
+ *
+ * @returns the appropriate conditions array depending on the vite version
+ *
+ */
+export function getDefaultServerConditions() {
+  return (vite as Vite6Options).defaultServerConditions ?? ['node']
+}

packages/vitest/src/node/plugins/index.ts

@@ -12,6 +12,7 @@ import { generateScopedClassName } from '../../integrations/css/css-modules'
 import { resolveApiServerConfig } from '../config/resolveConfig'
 import { Vitest } from '../core'
 import { createViteLogger, silenceImportViteIgnoreWarning } from '../viteLogger'
+import { getDefaultServerConditions } from './conditions'
 import { CoverageTransform } from './coverageTransform'
 import { CSSEnablerPlugin } from './cssEnabler'
 import { MocksPlugins } from './mocks'
@@ -73,6 +74,8 @@ export async function VitestPlugin(
           open = testConfig.uiBase ?? '/__vitest__/'
         }
 
+        const conditions = getDefaultServerConditions()
+
         const config: ViteConfig = {
           root: viteConfig.test?.root || options.root,
           esbuild:
@@ -90,7 +93,7 @@ export async function VitestPlugin(
             // setting this option can bypass that and fallback to cjs version
             mainFields: [],
             alias: testConfig.alias,
-            conditions: ['node'],
+            conditions,
           },
           server: {
             ...testConfig.api,
@@ -119,7 +122,7 @@ export async function VitestPlugin(
                 // by default Vite resolves `module` field, which not always a native ESM module
                 // setting this option can bypass that and fallback to cjs version
                 mainFields: [],
-                conditions: ['node'],
+                conditions,
               },
             },
           },

packages/vitest/src/node/plugins/workspace.ts

@@ -7,6 +7,7 @@ import { basename, dirname, relative, resolve } from 'pathe'
 import { configDefaults } from '../../defaults'
 import { generateScopedClassName } from '../../integrations/css/css-modules'
 import { createViteLogger, silenceImportViteIgnoreWarning } from '../viteLogger'
+import { getDefaultServerConditions } from './conditions'
 import { CoverageTransform } from './coverageTransform'
 import { CSSEnablerPlugin } from './cssEnabler'
 import { MocksPlugins } from './mocks'
@@ -62,14 +63,16 @@ export function WorkspaceVitestPlugin(
           }
         }
 
+        const conditions = getDefaultServerConditions()
+
         const config: ViteConfig = {
           root,
           resolve: {
             // by default Vite resolves `module` field, which not always a native ESM module
             // setting this option can bypass that and fallback to cjs version
             mainFields: [],
             alias: testConfig.alias,
-            conditions: ['node'],
+            conditions,
           },
           esbuild: viteConfig.esbuild === false
             ? false
@@ -104,7 +107,7 @@ export function WorkspaceVitestPlugin(
                 // by default Vite resolves `module` field, which not always a native ESM module
                 // setting this option can bypass that and fallback to cjs version
                 mainFields: [],
-                conditions: ['node'],
+                conditions,
               },
             },
           },

test/config/deps/test-dep-conditions/default.js

@@ -0,0 +1 @@
+export default 'default'

test/config/deps/test-dep-conditions/module.js

@@ -0,0 +1 @@
+export default 'module'

test/config/deps/test-dep-conditions/node.js

@@ -0,0 +1 @@
+export default 'node'

test/config/deps/test-dep-conditions/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "@vitest/test-dep-conditions",
+  "type": "module",
+  "private": true,
+  "exports": {
+    ".": {
+      "module": "./module.js",
+      "node": "./node.js",
+      "default": "./default.js"
+    }
+  }
+}

test/config/fixtures/conditions-subpackage/module.js

@@ -0,0 +1 @@
+export default 'module'

test/config/fixtures/default-conditions/default-conditions.test.js

@@ -0,0 +1,6 @@
+import { test, expect } from 'vitest';
+import condition from '@vitest/test-dep-conditions';
+
+test('condition is correct', () => {
+  expect(condition).toBe('module')
+})

test/config/fixtures/default-conditions/vitest.config.ts

@@ -0,0 +1,3 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({})

test/config/package.json

@@ -6,6 +6,7 @@
     "test": "vitest --typecheck.enabled"
   },
   "devDependencies": {
+    "@vitest/test-dep-conditions": "file:./deps/test-dep-conditions",
     "tinyexec": "^0.3.2",
     "vite": "latest",
     "vitest": "workspace:*"

test/config/test/default-conditions.test.ts

@@ -0,0 +1,23 @@
+import { expect, test } from 'vitest'
+import { runVitest } from '../../test-utils'
+
+test('"module" condition for external dep', async () => {
+  const { stderr } = await runVitest({
+    root: 'fixtures/default-conditions',
+  })
+
+  expect(stderr).toBe('')
+})
+
+test('"module" condition for inline dep', async () => {
+  const { stderr } = await runVitest({
+    root: 'fixtures/default-conditions',
+    server: {
+      deps: {
+        inline: ['@vitest/test-dep-conditions'],
+      },
+    },
+  })
+
+  expect(stderr).toBe('')
+})