Fix template literal whitespace collapse for adjacent quasis (#427)

* Fix template literal whitespace collapse for adjacent quasis

* Update changelog

---------

Co-authored-by: Jordan Pittman <jordan@cryptica.me>

Author: Dunqing

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- Collapse whitespace in template literals with adjacent quasis ([#427](https://github.com/tailwindlabs/prettier-plugin-tailwindcss/pull/427))
 
 ## [0.7.2] - 2025-12-01
 

src/index.ts

@@ -630,7 +630,7 @@ function canCollapseWhitespaceIn(path: Path<import('@babel/types').Node, any>) {
       let nodeEnd = entry.node.end ?? null
 
       for (let quasi of entry.parent.quasis) {
-        let quasiStart = quasi.end ?? null
+        let quasiStart = quasi.start ?? null
         let quasiEnd = quasi.end ?? null
 
         if (nodeStart !== null && quasiEnd !== null && nodeStart - quasiEnd <= 2) {

tests/format.test.ts

@@ -96,6 +96,14 @@ describe('whitespace', () => {
     expect(result).toEqual(";<div className={`header${isExtendable ? ' header-extendable' : ''}`} />")
   })
 
+  test('whitespace is not trimmed before template literal quasis without leading space', async ({ expect }) => {
+    let result = await format(";<div className={`${foo ? 'sm:p-0 p-0 ' : ''}header`}></div>", {
+      parser: 'babel',
+    })
+
+    expect(result).toEqual(";<div className={`${foo ? 'p-0 sm:p-0 ' : ''}header`}></div>")
+  })
+
   test('duplicate classes are dropped', async ({ expect }) => {
     let result = await format('<div class="underline line-through underline flex"></div>')