diff --git a/packages/browser/src/client/tester/tester.ts b/packages/browser/src/client/tester/tester.ts
index 4a309db077fc..3bdc80e09fd5 100644
--- a/packages/browser/src/client/tester/tester.ts
+++ b/packages/browser/src/client/tester/tester.ts
@@ -140,8 +140,17 @@ async function executeTests(method: 'run' | 'collect', files: string[]) {
   debug('prepare time', state.durations.prepare, 'ms')
 
   try {
-    await setupCommonEnv(config)
-    await startCoverageInsideWorker(config.coverage, executor)
+    await Promise.all([
+      setupCommonEnv(config),
+      startCoverageInsideWorker(config.coverage, executor),
+      (async () => {
+        const VitestIndex = await import('vitest')
+        Object.defineProperty(window, '__vitest_index__', {
+          value: VitestIndex,
+          enumerable: false,
+        })
+      })(),
+    ])
 
     for (const file of files) {
       state.filepath = file
@@ -168,7 +177,13 @@ async function executeTests(method: 'run' | 'collect', files: string[]) {
       }, 'Cleanup Error')
     }
     state.environmentTeardownRun = true
-    await stopCoverageInsideWorker(config.coverage, executor)
+    await stopCoverageInsideWorker(config.coverage, executor).catch((error) => {
+      client.rpc.onUnhandledError({
+        name: error.name,
+        message: error.message,
+        stack: String(error.stack),
+      }, 'Coverage Error').catch(() => {})
+    })
 
     debug('finished running tests')
     done(files)
diff --git a/packages/browser/src/node/plugin.ts b/packages/browser/src/node/plugin.ts
index f2516aca04fd..10c5f535418e 100644
--- a/packages/browser/src/node/plugin.ts
+++ b/packages/browser/src/node/plugin.ts
@@ -10,6 +10,7 @@ import { type Plugin, coverageConfigDefaults } from 'vitest/config'
 import { toArray } from '@vitest/utils'
 import { defaultBrowserPort } from 'vitest/config'
 import { dynamicImportPlugin } from '@vitest/mocker/node'
+import MagicString from 'magic-string'
 import BrowserContext from './plugins/pluginContext'
 import type { BrowserServer } from './server'
 import { resolveOrchestrator } from './serverOrchestrator'
@@ -349,6 +350,22 @@ export default (browserServer: BrowserServer, base = '/'): Plugin[] => {
         }
       },
     },
+    {
+      name: 'vitest:browser:in-source-tests',
+      transform(code, id) {
+        if (!project.isTestFile(id) || !code.includes('import.meta.vitest')) {
+          return
+        }
+        const s = new MagicString(code, { filename: cleanUrl(id) })
+        s.prepend(
+          `import.meta.vitest = __vitest_index__;\n`,
+        )
+        return {
+          code: s.toString(),
+          map: s.generateMap({ hires: true }),
+        }
+      },
+    },
     // TODO: remove this when @testing-library/vue supports ESM
     {
       name: 'vitest:browser:support-testing-library',
@@ -445,3 +462,8 @@ function resolveCoverageFolder(project: WorkspaceProject) {
 
   return [resolve(root, subdir), `/${basename(root)}/${subdir}/`]
 }
+
+const postfixRE = /[?#].*$/
+function cleanUrl(url: string): string {
+  return url.replace(postfixRE, '')
+}
diff --git a/packages/ui/client/composables/explorer/collector.ts b/packages/ui/client/composables/explorer/collector.ts
index 55178f0a494d..1c9473eee873 100644
--- a/packages/ui/client/composables/explorer/collector.ts
+++ b/packages/ui/client/composables/explorer/collector.ts
@@ -304,7 +304,7 @@ function collectData(summary: CollectorInfo) {
       file.prepareDuration = f.prepareDuration
       file.environmentLoad = f.environmentLoad
       file.collectDuration = f.collectDuration
-      file.duration = f.result?.duration
+      file.duration = f.result?.duration != null ? Math.round(f.result?.duration) : undefined
       file.state = f.result?.state
     }
     time += Math.max(0, f.collectDuration || 0)
diff --git a/packages/ui/client/composables/explorer/utils.ts b/packages/ui/client/composables/explorer/utils.ts
index 73f948d67528..01d02b32a0e0 100644
--- a/packages/ui/client/composables/explorer/utils.ts
+++ b/packages/ui/client/composables/explorer/utils.ts
@@ -69,7 +69,7 @@ export function createOrUpdateFileNode(
       tasks: [],
       typecheck: !!file.meta && 'typecheck' in file.meta,
       indent: 0,
-      duration: file.result?.duration,
+      duration: file.result?.duration != null ? Math.round(file.result?.duration) : undefined,
       filepath: file.filepath,
       projectName: file.projectName || '',
       projectNameColor: getProjectNameColor(file.projectName),
@@ -132,6 +132,9 @@ export function createOrUpdateNode(
 ) {
   const node = explorerTree.nodes.get(parentId) as ParentTreeNode | undefined
   let taskNode: UITaskTreeNode | undefined
+  const duration = task.result?.duration != null
+    ? Math.round(task.result?.duration)
+    : undefined
   if (node) {
     taskNode = explorerTree.nodes.get(task.id)
     if (taskNode) {
@@ -141,7 +144,7 @@ export function createOrUpdateNode(
       }
 
       taskNode.mode = task.mode
-      taskNode.duration = task.result?.duration
+      taskNode.duration = duration
       taskNode.state = task.result?.state
     }
     else {
@@ -156,7 +159,7 @@ export function createOrUpdateNode(
           expandable: false,
           expanded: false,
           indent: node.indent + 1,
-          duration: task.result?.duration,
+          duration,
           state: task.result?.state,
         } as TestTreeNode | CustomTestTreeNode
       }
@@ -174,7 +177,7 @@ export function createOrUpdateNode(
           children: new Set(),
           tasks: [],
           indent: node.indent + 1,
-          duration: task.result?.duration,
+          duration,
           state: task.result?.state,
         } as SuiteTreeNode
       }
diff --git a/test/browser/specs/runner.test.ts b/test/browser/specs/runner.test.ts
index 5065cc3498bd..e3ae04c9cffb 100644
--- a/test/browser/specs/runner.test.ts
+++ b/test/browser/specs/runner.test.ts
@@ -23,14 +23,21 @@ describe('running browser tests', async () => {
       console.error(stderr)
     })
 
-    expect(browserResultJson.testResults).toHaveLength(18)
-    expect(passedTests).toHaveLength(16)
+    expect(browserResultJson.testResults).toHaveLength(19)
+    expect(passedTests).toHaveLength(17)
     expect(failedTests).toHaveLength(2)
 
     expect(stderr).not.toContain('has been externalized for browser compatibility')
     expect(stderr).not.toContain('Unhandled Error')
   })
 
+  test('runs in-source tests', () => {
+    expect(stdout).toContain('src/actions.ts')
+    const actionsTest = passedTests.find(t => t.name.includes('/actions.ts'))
+    expect(actionsTest).toBeDefined()
+    expect(actionsTest.assertionResults).toHaveLength(1)
+  })
+
   test('correctly prints error', () => {
     expect(stderr).toContain('expected 1 to be 2')
     expect(stderr).toMatch(/- 2\s+\+ 1/)
diff --git a/test/browser/src/actions.ts b/test/browser/src/actions.ts
index 55ae85133596..bb783e81d065 100644
--- a/test/browser/src/actions.ts
+++ b/test/browser/src/actions.ts
@@ -1,3 +1,11 @@
 export function plus(a: number, b: number) {
   return a + b
 }
+
+if (import.meta.vitest) {
+  const { test, expect } = import.meta.vitest
+
+  test('in-source plus works correctly', () => {
+    expect(plus(1, 2)).toBe(3)
+  })
+}
diff --git a/test/browser/tsconfig.json b/test/browser/tsconfig.json
index 0468f44e9342..083a747ea373 100644
--- a/test/browser/tsconfig.json
+++ b/test/browser/tsconfig.json
@@ -9,7 +9,8 @@
     "types": [
       "vite/client",
       "@vitest/browser/providers/playwright",
-      "vitest-browser-react"
+      "vitest-browser-react",
+      "vitest/import-meta"
     ],
     "esModuleInterop": true
   }
diff --git a/test/browser/vitest.config.mts b/test/browser/vitest.config.mts
index ba958fb752ba..d51f62255d0c 100644
--- a/test/browser/vitest.config.mts
+++ b/test/browser/vitest.config.mts
@@ -28,6 +28,7 @@ export default defineConfig({
   },
   test: {
     include: ['test/**.test.{ts,js,tsx}'],
+    includeSource: ['src/*.ts'],
     // having a snapshot environment doesn't affect browser tests
     snapshotEnvironment: './custom-snapshot-env.ts',
     browser: {
diff --git a/test/browser/vitest.config.unit.mts b/test/browser/vitest.config.unit.mts
index a2a1707127d2..0618ce0ca59a 100644
--- a/test/browser/vitest.config.unit.mts
+++ b/test/browser/vitest.config.unit.mts
@@ -8,7 +8,7 @@ export default defineConfig({
         singleFork: true,
       },
     },
-    hookTimeout: process.env.CI ? 120_000 : 10_000,
-    testTimeout: process.env.CI ? 120_000 : 10_000,
+    hookTimeout: process.env.CI ? 120_000 : 20_000,
+    testTimeout: process.env.CI ? 120_000 : 20_000,
   },
 })