Formatter: Fix whitespace preservation around ERB tags and punctuation

javascript/packages/formatter/src/format-helpers.ts

@@ -194,7 +194,9 @@ export function isERBTag(text: string): boolean {
  * Check if a string ends with an ERB tag
  */
 export function endsWithERBTag(text: string): boolean {
-  return /%>$/.test(text.trim())
+  const trimmed = text.trim()
+
+  return /%>$/.test(trimmed) || /%>\S+$/.test(trimmed)
 }
 
 /**

javascript/packages/formatter/src/format-printer.ts

@@ -1862,7 +1862,7 @@ export class FormatPrinter extends Printer {
     const firstWord = words[0]
     const firstChar = firstWord[0]
 
-    if (!/[a-zA-Z0-9.!?:;]/.test(firstChar)) {
+    if (/\s/.test(firstChar)) {
       return false
     }
 
@@ -1879,6 +1879,11 @@ export class FormatPrinter extends Printer {
         unit: { content: remainingText, type: 'text', isAtomic: false, breaksFlow: false },
         node: textNode
       })
+    } else if (endsWithWhitespace(textNode.content)) {
+      result.push({
+        unit: { content: ' ', type: 'text', isAtomic: false, breaksFlow: false },
+        node: textNode
+      })
     }
 
     return true
@@ -1955,10 +1960,8 @@ export class FormatPrinter extends Printer {
       const hasWhitespace = this.hasWhitespaceBeforeNode(children, lastProcessedIndex, index, child)
       const lastUnit = result[result.length - 1]
       const lastIsAtomic = lastUnit.unit.isAtomic && (lastUnit.unit.type === 'erb' || lastUnit.unit.type === 'inline')
-      const trimmed = child.content.trim()
-      const startsWithClosingPunct = trimmed.length > 0 && /^[.!?:;]/.test(trimmed)
 
-      if (lastIsAtomic && (!hasWhitespace || startsWithClosingPunct) && this.tryMergeTextAfterAtomic(result, child)) {
+      if (lastIsAtomic && !hasWhitespace && this.tryMergeTextAfterAtomic(result, child)) {
         return
       }
     }

javascript/packages/formatter/test/erb/erb.test.ts

@@ -165,7 +165,7 @@ describe("@herb-tools/formatter", () => {
 
     expect(result).toBe(dedent`
       <h3>
-        <%= link_to "Start", start_path %> &rsquo;s overview of
+        <%= link_to "Start", start_path %>&rsquo;s overview of
         <%= link_to "Section", section_path %>, <%= link_to "End", end_path %>.
       </h3>
     `)