fix(analyze): check if a fragment has only one child element using tokens.

crates/biome_js_analyze/src/lint/complexity/no_useless_fragments.rs

@@ -161,9 +161,28 @@ impl Rule for NoUselessFragments {
 
                 let child_list = fragment.children();
 
+                let mut self_closing_or_element_count = 0;
+
+                for child in child_list.iter() {
+                    match child.syntax().kind() {
+                        JsSyntaxKind::JSX_SELF_CLOSING_ELEMENT
+                        | JsSyntaxKind::JSX_ELEMENT
+                        | JsSyntaxKind::JSX_EXPRESSION_CHILD
+                        | JsSyntaxKind::JSX_TEXT => {
+                            if child.syntax().kind() == JsSyntaxKind::JSX_TEXT
+                                && child_list.len() > 1
+                            {
+                                continue;
+                            }
+                            self_closing_or_element_count += 1;
+                        }
+                        _ => {}
+                    }
+                }
+
                 if !parents_where_fragments_must_be_preserved {
                     match child_list.first() {
-                        Some(first) if child_list.len() == 1 => {
+                        Some(first) if self_closing_or_element_count == 1 => {
                             if JsxText::can_cast(first.syntax().kind()) && in_jsx_attr_expr {
                                 return None;
                             }

crates/biome_js_analyze/tests/specs/complexity/noUselessFragments/issue_3545.jsx

@@ -0,0 +1,4 @@
+// https://github.com/biomejs/biome/issues/3545
+<>
+	<Component />
+</>;

crates/biome_js_analyze/tests/specs/complexity/noUselessFragments/issue_3545.jsx.snap

@@ -0,0 +1,41 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+assertion_line: 84
+expression: issue_3545.jsx
+---
+# Input
+```jsx
+// https://github.com/biomejs/biome/issues/3545
+<>
+	<Component />
+</>;
+
+```
+
+# Diagnostics
+```
+issue_3545.jsx:2:1 lint/complexity/noUselessFragments  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Avoid using unnecessary Fragment.
+
+    1 │ // https://github.com/biomejs/biome/issues/3545
+  > 2 │ <>
+      │ ^^
+  > 3 │ 	<Component />
+  > 4 │ </>;
+      │ ^^^
+    5 │ 
+
+  i A fragment is redundant if it contains only one child, or if it is the child of a html element, and is not a keyed fragment.
+
+  i Unsafe fix: Remove the Fragment
+
+    1 1 │   // https://github.com/biomejs/biome/issues/3545
+    2   │ - <>
+    3   │ - → <Component·/>
+    4   │ - </>;
+      2 │ + "";
+    5 3 │   
+
+
+```