add integration tests to validate piping to the CLI

integrations/execute.js

@@ -21,10 +21,6 @@ module.exports = function $(command, options = {}) {
   let abortController = new AbortController()
   let cwd = resolveToolRoot()
 
-  let args = command.split(' ')
-  command = args.shift()
-  command = command === 'node' ? command : path.resolve(cwd, 'node_modules', '.bin', command)
-
   let stdoutMessages = []
   let stderrMessages = []
 
@@ -55,7 +51,9 @@ module.exports = function $(command, options = {}) {
   }, 200)
 
   let runningProcess = new Promise((resolve, reject) => {
-    let child = spawn(command, args, {
+    let child = spawn(command, {
+      stdio: 'inherit',
+      shell: true,
       ...options,
       env: {
         ...process.env,

integrations/tailwindcss-cli/tests/integration.test.js

@@ -27,6 +27,28 @@ describe('static build', () => {
     )
   })
 
+  it('should be possible to pipe in data', async () => {
+    await writeInputFile('index.html', html`<div class="font-bold"></div>`)
+
+    let initialCss = css`
+      @tailwind base;
+      @tailwind components;
+      @tailwind utilities;
+    `
+
+    await $('cat ./src/index.css | node ../../lib/cli.js -o ./dist/main.css', {
+      env: { NODE_ENV: 'production' },
+    })
+
+    expect(await readOutputFile('main.css')).toIncludeCss(
+      css`
+        .font-bold {
+          font-weight: 700;
+        }
+      `
+    )
+  })
+
   it('should safelist a list of classes to always include', async () => {
     await writeInputFile('index.html', html`<div class="font-bold"></div>`)
     await writeInputFile(