Preserve whitespace in text surrounded by newlines (#816)

* fix: replace incorrect use of `assert.ok` with `assert.match`

* fix: don't remove all surrounding whitespace from text nodes surrounded by newlines

* fix: revert go tests

* fix: update js tests

* add changeset

.changeset/soft-eggs-exercise.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/compiler': patch
+---
+
+Do not remove surrounding whitespace from text surrounded by newlines when `compressHTML` is enabled

internal/transform/transform.go

@@ -263,59 +263,63 @@ func isRawElement(n *astro.Node) bool {
 func collapseWhitespace(doc *astro.Node) {
 	walk(doc, func(n *astro.Node) {
 		if n.Type == astro.TextNode {
+			// Don't trim any whitespace if the node or any of its ancestors is raw
 			if n.Closest(isRawElement) != nil {
 				return
 			}
-			// Top-level expression children
+
+			// Trim the whitespace on each end of top-level expressions
 			if n.Parent != nil && n.Parent.Expression {
-				// Trim left for first child
+				// Trim left whitespace in the first child
 				if n.PrevSibling == nil {
 					n.Data = strings.TrimLeftFunc(n.Data, unicode.IsSpace)
 				}
-				// Trim right for last child
+				// Trim right whitespace in the last child
 				if n.NextSibling == nil {
 					n.Data = strings.TrimRightFunc(n.Data, unicode.IsSpace)
 				}
-				// Otherwise don't trim this!
+				// Don't trim any more!
 				return
 			}
+
+			// If the node is only whitespace, clear it
 			if len(strings.TrimFunc(n.Data, unicode.IsSpace)) == 0 {
 				n.Data = ""
 				return
 			}
+
+			// Collapse left whitespace into a single space
 			originalLen := len(n.Data)
-			hasLeftNewline := false
+			hasNewline := false
 			n.Data = strings.TrimLeftFunc(n.Data, func(r rune) bool {
 				if r == '\n' {
-					hasLeftNewline = true
+					hasNewline = true
 				}
 				return unicode.IsSpace(r)
 			})
 			if originalLen != len(n.Data) {
-				if hasLeftNewline {
+				if hasNewline {
 					n.Data = "\n" + n.Data
 				} else {
 					n.Data = " " + n.Data
 				}
 			}
-			hasRightNewline := false
+			// Collapse right whitespace into a single space
 			originalLen = len(n.Data)
+			hasNewline = false
 			n.Data = strings.TrimRightFunc(n.Data, func(r rune) bool {
 				if r == '\n' {
-					hasRightNewline = true
+					hasNewline = true
 				}
 				return unicode.IsSpace(r)
 			})
 			if originalLen != len(n.Data) {
-				if hasRightNewline {
+				if hasNewline {
 					n.Data = n.Data + "\n"
 				} else {
 					n.Data = n.Data + " "
 				}
 			}
-			if hasLeftNewline && hasRightNewline {
-				n.Data = strings.TrimSpace(n.Data)
-			}
 		}
 	})
 }

internal/transform/transform_test.go

@@ -355,7 +355,7 @@ func TestCompactTransform(t *testing.T) {
 		{
 			name:   "collapse surrounding newlines",
 			source: "<div>\n\n\tC O O L\n\n\t</div>",
-			want:   "<div>C O O L</div>",
+			want:   "<div>\nC O O L\n</div>",
 		},
 		{
 			name:   "expression trim first",

packages/compiler/test/compact/minify.ts

@@ -14,14 +14,14 @@ test('basic', async () => {
 
 test('preservation', async () => {
   assert.match(await minify(`<pre>  !  </pre>`), '$$render`<pre>  !  </pre>`');
-  assert.ok(await minify(`<div is:raw>  !  </div>`), '$$render`<div>  !  </div>`');
-  assert.ok(await minify(`<Markdown>  !  </Markdown>`), '$$render`  !  `');
+  assert.match(await minify(`<div is:raw>  !  </div>`), '$$render`<div>  !  </div>`');
+  assert.match(await minify(`<Markdown is:raw>  !  </Markdown>`), '$$render`  !  `');
 });
 
 test('collapsing', async () => {
-  assert.ok(await minify(`<span> inline </span>`), '$$render`<span> inline </span>`');
-  assert.ok(await minify(`<span>\n inline \t{\t expression \t}</span>`), '$$render`<span> inline ${ expression } </span>`');
-  assert.ok(await minify(`<span> inline { expression }</span>`), '$$render`<span> inline ${ expression }</span>`');
+  assert.match(await minify(`<span> inline </span>`), '$$render`<span> inline </span>`');
+  assert.match(await minify(`<span>\n inline \t{\t expression \t}</span>`), '$$render`<span>\ninline ${expression}</span>`');
+  assert.match(await minify(`<span> inline { expression }</span>`), '$$render`<span> inline ${expression}</span>`');
 });
 
 test('space normalization between attributes', async () => {
@@ -150,9 +150,17 @@ test('space normalization around text', async () => {
   );
 });
 
-test('surrounded by newlines #7401', async () => {
+test('surrounded by newlines (astro#7401)', async () => {
   const input = '<span>foo</span>\n\t\tbar\n\t\t<span>baz</span>';
-  const output = '<span>foo</span>bar<span>baz</span>';
+  const output = '<span>foo</span>\nbar\n<span>baz</span>';
+  const result = await minify(input);
+
+  assert.match(result, output);
+});
+
+test('separated by newlines (#815)', async () => {
+  const input = '<p>\n\ta\n\t<span>b</span>\n\tc\n</p>';
+  const output = '<p>\na\n<span>b</span>\nc\n</p>';
   const result = await minify(input);
 
   assert.match(result, output);