feat: add support ofr default value syntax

- Introduced a new script `test-default-values.js` to validate default value syntax in commands.
- Updated `package.json` to include the new test script in the e2e test command.
- Modified GitHub Actions workflow to run the new e2e tests.
- Enhanced `commandConvert` function to support default value syntax in environment variables.
- Added unit tests for the new functionality in `command-default-values.test.ts`.

.github/workflows/validate.yml

@@ -90,6 +90,9 @@ jobs:
       - name: 🐚 Run cross-env-shell e2e tests
         run: node e2e/test-cross-env-shell.js
 
+      - name: 🔧 Run default value syntax e2e tests
+        run: node e2e/test-default-values.js
+
   release:
     name: 🚀 Release
     needs: [build, e2e]

e2e/test-default-values.js

@@ -0,0 +1,185 @@
+#!/usr/bin/env node
+
+import { spawn } from 'child_process'
+import { dirname, join } from 'path'
+import { fileURLToPath } from 'url'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = dirname(__filename)
+
+// Path to the built cross-env binary
+const crossEnvPath = join(__dirname, '..', 'dist', 'bin', 'cross-env.js')
+
+function runCommand(command, args = []) {
+	return new Promise((resolve, reject) => {
+		const child = spawn('node', [command, ...args], {
+			stdio: ['pipe', 'pipe', 'pipe'],
+			env: { ...process.env },
+		})
+
+		let stdout = ''
+		let stderr = ''
+
+		child.stdout.on('data', (data) => {
+			stdout += data.toString()
+		})
+
+		child.stderr.on('data', (data) => {
+			stderr += data.toString()
+		})
+
+		child.on('close', (code) => {
+			if (code === 0) {
+				resolve({ stdout, stderr, code })
+			} else {
+				reject(new Error(`Command failed with code ${code}: ${stderr}`))
+			}
+		})
+
+		child.on('error', (error) => {
+			reject(error)
+		})
+	})
+}
+
+async function runTests() {
+	console.log('🧪 Running cross-env default value syntax e2e tests...')
+
+	const tests = [
+		{
+			name: 'Default value syntax when variable is undefined',
+			test: async () => {
+				// Test that the command conversion works by using echo to see the converted command
+				const result = await runCommand(crossEnvPath, [
+					'echo',
+					'wrangler dev --port ${PORT:-8787}',
+				])
+
+				// On Windows, this should convert to the default value
+				// On Unix, it should remain unchanged
+				const expected =
+					process.platform === 'win32'
+						? 'wrangler dev --port 8787'
+						: 'wrangler dev --port ${PORT:-8787}'
+				if (result.stdout.trim() !== expected) {
+					throw new Error(
+						`Expected '${expected}', got '${result.stdout.trim()}'`,
+					)
+				}
+			},
+		},
+		{
+			name: 'Default value syntax when variable is defined',
+			test: async () => {
+				const result = await runCommand(crossEnvPath, [
+					'PORT=3000',
+					'echo',
+					'wrangler dev --port ${PORT:-8787}',
+				])
+
+				// On Windows, this should convert to the defined value
+				// On Unix, it should remain unchanged
+				const expected =
+					process.platform === 'win32'
+						? 'wrangler dev --port 3000'
+						: 'wrangler dev --port ${PORT:-8787}'
+				if (result.stdout.trim() !== expected) {
+					throw new Error(
+						`Expected '${expected}', got '${result.stdout.trim()}'`,
+					)
+				}
+			},
+		},
+		{
+			name: 'Multiple default value syntaxes',
+			test: async () => {
+				const result = await runCommand(crossEnvPath, [
+					'HOST=localhost',
+					'echo',
+					'wrangler dev --host ${HOST:-0.0.0.0} --port ${PORT:-8787}',
+				])
+
+				// On Windows, should use defined value for HOST and default for PORT
+				// On Unix, should remain unchanged
+				const expected =
+					process.platform === 'win32'
+						? 'wrangler dev --host localhost --port 8787'
+						: 'wrangler dev --host ${HOST:-0.0.0.0} --port ${PORT:-8787}'
+				if (result.stdout.trim() !== expected) {
+					throw new Error(
+						`Expected '${expected}', got '${result.stdout.trim()}'`,
+					)
+				}
+			},
+		},
+		{
+			name: 'Default value with special characters',
+			test: async () => {
+				const result = await runCommand(crossEnvPath, [
+					'echo',
+					'node app.js --env ${NODE_ENV:-development}',
+				])
+
+				// On Windows, should use the default value
+				// On Unix, should remain unchanged
+				const expected =
+					process.platform === 'win32'
+						? 'node app.js --env development'
+						: 'node app.js --env ${NODE_ENV:-development}'
+				if (result.stdout.trim() !== expected) {
+					throw new Error(
+						`Expected '${expected}', got '${result.stdout.trim()}'`,
+					)
+				}
+			},
+		},
+		{
+			name: 'Default value with spaces',
+			test: async () => {
+				const result = await runCommand(crossEnvPath, [
+					'echo',
+					'echo ${MESSAGE:-hello world}',
+				])
+
+				// On Windows, should use the default value with spaces
+				// On Unix, should remain unchanged
+				const expected =
+					process.platform === 'win32'
+						? 'echo hello world'
+						: 'echo ${MESSAGE:-hello world}'
+				if (result.stdout.trim() !== expected) {
+					throw new Error(
+						`Expected '${expected}', got '${result.stdout.trim()}'`,
+					)
+				}
+			},
+		},
+	]
+
+	let passed = 0
+	let failed = 0
+
+	for (const test of tests) {
+		try {
+			console.log(`  ✓ ${test.name}`)
+			await test.test()
+			passed++
+		} catch (error) {
+			console.log(`  ✗ ${test.name}: ${error.message}`)
+			failed++
+		}
+	}
+
+	console.log(`\n📊 Test Results: ${passed} passed, ${failed} failed`)
+
+	if (failed > 0) {
+		process.exit(1)
+	}
+
+	console.log('✅ All default value syntax e2e tests passed!')
+}
+
+runTests().catch((error) => {
+	console.error('❌ Test runner failed:', error)
+	process.exit(1)
+})

package.json

@@ -24,7 +24,7 @@
     "test:ui": "vitest --ui",
     "test:run": "vitest run",
     "test:coverage": "vitest run --coverage",
-    "test:e2e": "node e2e/test-cross-env.js && node e2e/test-cross-env-shell.js",
+    "test:e2e": "node e2e/test-cross-env.js && node e2e/test-cross-env-shell.js && node e2e/test-default-values.js",
     "validate": "npm run build && npm run typecheck && npm run lint && npm run format:check && npm run test:run"
   },
   "files": [

src/__tests__/command-default-values.test.ts

@@ -0,0 +1,103 @@
+import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest'
+import { commandConvert } from '../command.js'
+import * as isWindowsModule from '../is-windows.js'
+
+vi.mock('../is-windows.js')
+
+describe('commandConvert - Environment Variable Default Values', () => {
+	beforeEach(() => {
+		vi.clearAllMocks()
+	})
+
+	afterEach(() => {
+		vi.clearAllMocks()
+	})
+
+	test('should handle ${VAR:-default} syntax on Windows when VAR is undefined', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = {} // PORT is not defined
+		const command = 'wrangler dev --port ${PORT:-8787}'
+
+		const result = commandConvert(command, env)
+
+		// Should use the default value when PORT is not defined
+		expect(result).toBe('wrangler dev --port 8787')
+	})
+
+	test('should handle ${VAR:-default} syntax on Windows when VAR is defined', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = { PORT: '3000' }
+		const command = 'wrangler dev --port ${PORT:-8787}'
+
+		const result = commandConvert(command, env)
+
+		// Should use the defined value when PORT is defined
+		expect(result).toBe('wrangler dev --port 3000')
+	})
+
+	test('should handle ${VAR:-default} syntax on Unix (no conversion needed)', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(false)
+		const env = {} // PORT is not defined
+		const command = 'wrangler dev --port ${PORT:-8787}'
+
+		const result = commandConvert(command, env)
+
+		// On Unix, no conversion is needed
+		expect(result).toBe('wrangler dev --port ${PORT:-8787}')
+	})
+
+	test('should handle simple ${VAR} syntax on Windows', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = { PORT: '3000' }
+		const command = 'wrangler dev --port ${PORT}'
+
+		const result = commandConvert(command, env)
+
+		// This works correctly
+		expect(result).toBe('wrangler dev --port %PORT%')
+	})
+
+	test('should handle simple ${VAR} syntax on Windows when VAR is undefined', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = {} // PORT is not defined
+		const command = 'wrangler dev --port ${PORT}'
+
+		const result = commandConvert(command, env)
+
+		// This works correctly - strips undefined variables
+		expect(result).toBe('wrangler dev --port ')
+	})
+
+	test('should handle multiple default value syntaxes in one command', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = { HOST: 'localhost' } // PORT is not defined
+		const command = 'wrangler dev --host ${HOST:-0.0.0.0} --port ${PORT:-8787}'
+
+		const result = commandConvert(command, env)
+
+		// Should use defined value for HOST and default for PORT
+		expect(result).toBe('wrangler dev --host localhost --port 8787')
+	})
+
+	test('should handle default values with special characters', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = {} // NODE_ENV is not defined
+		const command = 'node app.js --env ${NODE_ENV:-development}'
+
+		const result = commandConvert(command, env)
+
+		// Should use the default value
+		expect(result).toBe('node app.js --env development')
+	})
+
+	test('should handle default values with spaces', () => {
+		vi.mocked(isWindowsModule.isWindows).mockReturnValue(true)
+		const env = {} // MESSAGE is not defined
+		const command = 'echo ${MESSAGE:-hello world}'
+
+		const result = commandConvert(command, env)
+
+		// Should use the default value with spaces
+		expect(result).toBe('echo hello world')
+	})
+})

src/command.ts

@@ -17,8 +17,25 @@ export function commandConvert(
 		return command
 	}
 
-	const envUnixRegex = /\$(\w+)|\${(\w+)}/g // $my_var or ${my_var}
+	// Handle simple variables: $var or ${var}
-	const convertedCmd = command.replace(envUnixRegex, (match, $1, $2) => {
+	const simpleEnvRegex = /\$(\w+)|\${(\w+)}/g
+	// Handle bash parameter expansion with default values: ${var:-default}
+	const defaultValueRegex = /\$\{(\w+):-([^}]+)\}/g
+
+	let convertedCmd = command
+
+	// First, handle bash parameter expansion with default values
+	convertedCmd = convertedCmd.replace(
+		defaultValueRegex,
+		(match, varName, defaultValue) => {
+			// If the variable exists, use its value; otherwise use the default
+			const value = env[varName] || defaultValue
+			return value
+		},
+	)
+
+	// Then handle simple variable references
+	convertedCmd = convertedCmd.replace(simpleEnvRegex, (match, $1, $2) => {
 		const varName = $1 || $2
 		// In Windows, non-existent variables are not replaced by the shell,
 		// so for example "echo %FOO%" will literally print the string "%FOO%", as