diff --git a/test/bun/index.test.ts b/test/bun/index.test.ts
index 2f523a29..8c5511d9 100644
--- a/test/bun/index.test.ts
+++ b/test/bun/index.test.ts
@@ -1,8 +1,17 @@
 import * as bun from '../../src/package-managers/bun'
 import chaiSetup from '../helpers/chaiSetup'
+import { testFail, testPass } from '../helpers/doctorHelpers'
+import stubVersions from '../helpers/stubVersions'
 
 chaiSetup()
 
+const mockNpmVersions = {
+  emitter20: '2.0.0',
+  'ncu-test-return-version': '2.0.0',
+  'ncu-test-tag': '1.1.0',
+  'ncu-test-v2': '2.0.0',
+}
+
 describe('bun', function () {
   it('list', async () => {
     const result = await bun.list({ cwd: __dirname })
@@ -13,4 +22,15 @@ describe('bun', function () {
     const { version } = await bun.latest('ncu-test-v2', '1.0.0', { cwd: __dirname })
     version!.should.equal('2.0.0')
   })
+
+  describe('doctor', function () {
+    this.timeout(3 * 60 * 1000)
+
+    let stub: { restore: () => void }
+    before(() => (stub = stubVersions(mockNpmVersions, { spawn: true })))
+    after(() => stub.restore())
+
+    testPass({ packageManager: 'bun' })
+    testFail({ packageManager: 'bun' })
+  })
 })
diff --git a/test/doctor.test.ts b/test/doctor.test.ts
index 8999f749..ff52445b 100644
--- a/test/doctor.test.ts
+++ b/test/doctor.test.ts
@@ -4,8 +4,8 @@ import path from 'path'
 import spawn from 'spawn-please'
 import { cliOptionsMap } from '../src/cli-options'
 import { chalkInit } from '../src/lib/chalk'
-import { PackageManagerName } from '../src/types/PackageManagerName'
 import chaiSetup from './helpers/chaiSetup'
+import { testFail, testPass } from './helpers/doctorHelpers'
 import stubVersions from './helpers/stubVersions'
 
 chaiSetup()
@@ -30,150 +30,6 @@ const ncu = async (
   return stdout
 }
 
-/** Assertions for npm or yarn when tests pass. */
-const testPass = ({ packageManager }: { packageManager: PackageManagerName }) => {
-  it('upgrade dependencies when tests pass', async function () {
-    // use dynamic import for ESM module
-    const { default: stripAnsi } = await import('strip-ansi')
-    const cwd = path.join(doctorTests, 'pass')
-    const pkgPath = path.join(cwd, 'package.json')
-    const nodeModulesPath = path.join(cwd, 'node_modules')
-    const lockfilePath = path.join(
-      cwd,
-      packageManager === 'yarn'
-        ? 'yarn.lock'
-        : packageManager === 'pnpm'
-          ? 'pnpm-lock.yaml'
-          : packageManager === 'bun'
-            ? 'bun.lockb'
-            : 'package-lock.json',
-    )
-    const pkgOriginal = await fs.readFile(path.join(cwd, 'package.json'), 'utf-8')
-    let stdout = ''
-    let stderr = ''
-
-    // touch yarn.lock
-    // yarn.lock is necessary otherwise yarn sees the package.json in the npm-check-updates directory and throws an error.
-    if (packageManager === 'yarn' || packageManager === 'bun') {
-      await fs.writeFile(lockfilePath, '')
-    }
-
-    try {
-      // explicitly set packageManager to avoid auto yarn detection
-      await ncu(
-        ['--doctor', '-u', '-p', packageManager],
-        {
-          stdout: function (data: string) {
-            stdout += data
-          },
-          stderr: function (data: string) {
-            stderr += data
-          },
-        },
-        { cwd },
-      )
-    } catch (e) {}
-
-    const pkgUpgraded = await fs.readFile(pkgPath, 'utf-8')
-
-    // cleanup before assertions in case they fail
-    await fs.writeFile(pkgPath, pkgOriginal)
-    await fs.rm(nodeModulesPath, { recursive: true, force: true })
-    await fs.rm(lockfilePath, { recursive: true, force: true })
-
-    // delete yarn cache
-    if (packageManager === 'yarn') {
-      await fs.rm(path.join(cwd, '.yarn'), { recursive: true, force: true })
-      await fs.rm(path.join(cwd, '.pnp.js'), { recursive: true, force: true })
-    }
-
-    // bun prints the run header to stderr instead of stdout
-    if (packageManager === 'bun') {
-      stripAnsi(stderr).should.equal('$ echo Success\n\n$ echo Success\n\n')
-    } else {
-      stderr.should.equal('')
-    }
-
-    // stdout should include normal output
-    stripAnsi(stdout).should.containIgnoreCase('Tests pass')
-    stripAnsi(stdout).should.containIgnoreCase('ncu-test-v2  ~1.0.0  →  ~2.0.0')
-
-    // package file should include upgrades
-    pkgUpgraded.should.containIgnoreCase('"ncu-test-v2": "~2.0.0"')
-  })
-}
-
-/** Assertions for npm or yarn when tests fail. */
-const testFail = ({ packageManager }: { packageManager: PackageManagerName }) => {
-  it('identify broken upgrade', async function () {
-    const cwd = path.join(doctorTests, 'fail')
-    const pkgPath = path.join(cwd, 'package.json')
-    const nodeModulesPath = path.join(cwd, 'node_modules')
-    const lockfilePath = path.join(
-      cwd,
-      packageManager === 'yarn'
-        ? 'yarn.lock'
-        : packageManager === 'pnpm'
-          ? 'pnpm-lock.yaml'
-          : packageManager === 'bun'
-            ? 'bun.lockb'
-            : 'package-lock.json',
-    )
-    const pkgOriginal = await fs.readFile(path.join(cwd, 'package.json'), 'utf-8')
-    let stdout = ''
-    let stderr = ''
-    let pkgUpgraded
-
-    // touch yarn.lock (see fail/README)
-    if (packageManager === 'yarn') {
-      await fs.writeFile(lockfilePath, '')
-    }
-
-    try {
-      // explicitly set packageManager to avoid auto yarn detection
-      await ncu(
-        ['--doctor', '-u', '-p', packageManager],
-        {
-          stdout: function (data: string) {
-            stdout += data
-          },
-          stderr: function (data: string) {
-            stderr += data
-          },
-        },
-        { cwd },
-      )
-    } finally {
-      pkgUpgraded = await fs.readFile(pkgPath, 'utf-8')
-      await fs.writeFile(pkgPath, pkgOriginal)
-      await fs.rm(nodeModulesPath, { recursive: true, force: true })
-      await fs.rm(lockfilePath, { recursive: true, force: true })
-
-      // delete yarn cache
-      if (packageManager === 'yarn') {
-        await fs.rm(path.join(cwd, '.yarn'), { recursive: true, force: true })
-        await fs.rm(path.join(cwd, '.pnp.js'), { recursive: true, force: true })
-      }
-    }
-
-    // stdout should include successful upgrades
-    stdout.should.containIgnoreCase('ncu-test-v2 ~1.0.0 →')
-    stdout.should.not.include('ncu-test-return-version ~1.0.0 →')
-    stdout.should.containIgnoreCase('emitter20 1.0.0 →')
-
-    // stderr should include first failing upgrade
-    stderr.should.containIgnoreCase('Breaks with v2.x')
-    stderr.should.not.include('ncu-test-v2 ~1.0.0 →')
-    stderr.should.containIgnoreCase('ncu-test-return-version ~1.0.0 →')
-    stderr.should.not.include('emitter20 1.0.0 →')
-
-    // package file should only include successful upgrades
-    pkgUpgraded.should.containIgnoreCase('"ncu-test-v2": "~2.0.0"')
-    pkgUpgraded.should.containIgnoreCase('"ncu-test-return-version": "~1.0.0"')
-    pkgUpgraded.should.not.include('"emitter20": "1.0.0"')
-  })
-}
-
 describe('doctor', function () {
   // 3 min timeout
   this.timeout(3 * 60 * 1000)
@@ -482,10 +338,4 @@ else {
     testPass({ packageManager: 'yarn' })
     testFail({ packageManager: 'yarn' })
   })
-
-  // TODO: Works locally, but not in GitHub action.
-  describe.skip('bun', () => {
-    testPass({ packageManager: 'bun' })
-    testFail({ packageManager: 'bun' })
-  })
 })
diff --git a/test/helpers/doctorHelpers.ts b/test/helpers/doctorHelpers.ts
new file mode 100644
index 00000000..6fce3601
--- /dev/null
+++ b/test/helpers/doctorHelpers.ts
@@ -0,0 +1,161 @@
+import fs from 'fs/promises'
+import path from 'path'
+import spawn from 'spawn-please'
+import { PackageManagerName } from '../../src/types/PackageManagerName'
+
+const bin = path.join(__dirname, '../../build/cli.js')
+const doctorTests = path.join(__dirname, '../test-data/doctor')
+
+/** Run the ncu CLI. */
+const ncu = async (
+  args: string[],
+  spawnPleaseOptions?: Parameters<typeof spawn>[2],
+  spawnOptions?: Parameters<typeof spawn>[3],
+) => {
+  const { stdout } = await spawn('node', [bin, ...args], spawnPleaseOptions, spawnOptions)
+  return stdout
+}
+
+/** Assertions for npm or yarn when tests pass. */
+export const testPass = ({ packageManager }: { packageManager: PackageManagerName }) => {
+  it('upgrade dependencies when tests pass', async function () {
+    // use dynamic import for ESM module
+    const { default: stripAnsi } = await import('strip-ansi')
+    const cwd = path.join(doctorTests, 'pass')
+    const pkgPath = path.join(cwd, 'package.json')
+    const nodeModulesPath = path.join(cwd, 'node_modules')
+    const lockfilePath = path.join(
+      cwd,
+      packageManager === 'yarn'
+        ? 'yarn.lock'
+        : packageManager === 'pnpm'
+          ? 'pnpm-lock.yaml'
+          : packageManager === 'bun'
+            ? 'bun.lockb'
+            : 'package-lock.json',
+    )
+    const pkgOriginal = await fs.readFile(path.join(cwd, 'package.json'), 'utf-8')
+    let stdout = ''
+    let stderr = ''
+
+    // touch yarn.lock
+    // yarn.lock is necessary otherwise yarn sees the package.json in the npm-check-updates directory and throws an error.
+    if (packageManager === 'yarn' || packageManager === 'bun') {
+      await fs.writeFile(lockfilePath, '')
+    }
+
+    try {
+      // explicitly set packageManager to avoid auto yarn detection
+      await ncu(
+        ['--doctor', '-u', '-p', packageManager],
+        {
+          stdout: function (data: string) {
+            stdout += data
+          },
+          stderr: function (data: string) {
+            stderr += data
+          },
+        },
+        { cwd },
+      )
+    } catch (e) {}
+
+    const pkgUpgraded = await fs.readFile(pkgPath, 'utf-8')
+
+    // cleanup before assertions in case they fail
+    await fs.writeFile(pkgPath, pkgOriginal)
+    await fs.rm(nodeModulesPath, { recursive: true, force: true })
+    await fs.rm(lockfilePath, { recursive: true, force: true })
+
+    // delete yarn cache
+    if (packageManager === 'yarn') {
+      await fs.rm(path.join(cwd, '.yarn'), { recursive: true, force: true })
+      await fs.rm(path.join(cwd, '.pnp.js'), { recursive: true, force: true })
+    }
+
+    // bun prints the run header to stderr instead of stdout
+    if (packageManager === 'bun') {
+      stripAnsi(stderr).should.equal('$ echo Success\n\n$ echo Success\n\n')
+    } else {
+      stderr.should.equal('')
+    }
+
+    // stdout should include normal output
+    stripAnsi(stdout).should.containIgnoreCase('Tests pass')
+    stripAnsi(stdout).should.containIgnoreCase('ncu-test-v2  ~1.0.0  →  ~2.0.0')
+
+    // package file should include upgrades
+    pkgUpgraded.should.containIgnoreCase('"ncu-test-v2": "~2.0.0"')
+  })
+}
+
+/** Assertions for npm or yarn when tests fail. */
+export const testFail = ({ packageManager }: { packageManager: PackageManagerName }) => {
+  it('identify broken upgrade', async function () {
+    const cwd = path.join(doctorTests, 'fail')
+    const pkgPath = path.join(cwd, 'package.json')
+    const nodeModulesPath = path.join(cwd, 'node_modules')
+    const lockfilePath = path.join(
+      cwd,
+      packageManager === 'yarn'
+        ? 'yarn.lock'
+        : packageManager === 'pnpm'
+          ? 'pnpm-lock.yaml'
+          : packageManager === 'bun'
+            ? 'bun.lockb'
+            : 'package-lock.json',
+    )
+    const pkgOriginal = await fs.readFile(path.join(cwd, 'package.json'), 'utf-8')
+    let stdout = ''
+    let stderr = ''
+    let pkgUpgraded
+
+    // touch yarn.lock (see fail/README)
+    if (packageManager === 'yarn') {
+      await fs.writeFile(lockfilePath, '')
+    }
+
+    try {
+      // explicitly set packageManager to avoid auto yarn detection
+      await ncu(
+        ['--doctor', '-u', '-p', packageManager],
+        {
+          stdout: function (data: string) {
+            stdout += data
+          },
+          stderr: function (data: string) {
+            stderr += data
+          },
+        },
+        { cwd },
+      )
+    } finally {
+      pkgUpgraded = await fs.readFile(pkgPath, 'utf-8')
+      await fs.writeFile(pkgPath, pkgOriginal)
+      await fs.rm(nodeModulesPath, { recursive: true, force: true })
+      await fs.rm(lockfilePath, { recursive: true, force: true })
+
+      // delete yarn cache
+      if (packageManager === 'yarn') {
+        await fs.rm(path.join(cwd, '.yarn'), { recursive: true, force: true })
+        await fs.rm(path.join(cwd, '.pnp.js'), { recursive: true, force: true })
+      }
+    }
+
+    // stdout should include successful upgrades
+    stdout.should.containIgnoreCase('ncu-test-v2 ~1.0.0 →')
+    stdout.should.not.include('ncu-test-return-version ~1.0.0 →')
+    stdout.should.containIgnoreCase('emitter20 1.0.0 →')
+
+    // stderr should include first failing upgrade
+    stderr.should.containIgnoreCase('Breaks with v2.x')
+    stderr.should.not.include('ncu-test-v2 ~1.0.0 →')
+    stderr.should.containIgnoreCase('ncu-test-return-version ~1.0.0 →')
+    stderr.should.not.include('emitter20 1.0.0 →')
+
+    // package file should only include successful upgrades
+    pkgUpgraded.should.containIgnoreCase('"ncu-test-v2": "~2.0.0"')
+    pkgUpgraded.should.containIgnoreCase('"ncu-test-return-version": "~1.0.0"')
+    pkgUpgraded.should.not.include('"emitter20": "1.0.0"')
+  })
+}