fix(formatter): should group nested test for TSConditionalType (#14661)

Align Prettier's behavior

Author: Dunqing

crates/oxc_formatter/src/utils/conditional.rs

@@ -4,7 +4,7 @@ use oxc_ast::ast::*;
 use oxc_span::{GetSpan, Span};
 
 use crate::{
-    Format, FormatResult, FormatWrite,
+    Format, FormatResult, FormatWrite, format_args,
     formatter::{Formatter, prelude::*, trivia::FormatTrailingComments},
     generated::ast_nodes::{AstNode, AstNodes},
     utils::format_node_without_trailing_comments::FormatNodeWithoutTrailingComments,
@@ -373,41 +373,34 @@ impl<'a> FormatConditionalLike<'a, '_> {
         f: &mut Formatter<'f, 'a>,
         layout: ConditionalLayout,
     ) -> FormatResult<()> {
-        let format_inner = format_with(|f| match self.conditional {
-            ConditionalLike::ConditionalExpression(conditional) => {
-                write!(f, FormatNodeWithoutTrailingComments(conditional.test()))?;
-                format_trailing_comments(
-                    conditional.test.span().end,
-                    conditional.consequent.span().start,
-                    b'?',
-                    f,
-                )
-            }
-            ConditionalLike::TSConditionalType(conditional) => {
-                write!(
-                    f,
-                    [
-                        conditional.check_type(),
-                        space(),
-                        "extends",
-                        space(),
-                        FormatNodeWithoutTrailingComments(conditional.extends_type())
-                    ]
-                )?;
+        let format_inner = format_with(|f| {
+            let (start, end) = match self.conditional {
+                ConditionalLike::ConditionalExpression(conditional) => {
+                    write!(f, FormatNodeWithoutTrailingComments(conditional.test()))?;
+                    (conditional.test.span().end, conditional.consequent.span().start)
+                }
+                ConditionalLike::TSConditionalType(conditional) => {
+                    write!(
+                        f,
+                        [
+                            conditional.check_type(),
+                            space(),
+                            "extends",
+                            space(),
+                            FormatNodeWithoutTrailingComments(conditional.extends_type())
+                        ]
+                    )?;
+                    (conditional.extends_type.span().end, conditional.true_type.span().start)
+                }
+            };
 
-                format_trailing_comments(
-                    conditional.extends_type.span().end,
-                    conditional.true_type.span().start,
-                    b'?',
-                    f,
-                )
-            }
+            format_trailing_comments(start, end, b'?', f)
         });
 
         if layout.is_nested_alternate() {
             write!(f, [align(2, &format_inner)])
         } else {
-            format_inner.fmt(f)
+            write!(f, format_inner)
         }
     }
 
@@ -420,27 +413,19 @@ impl<'a> FormatConditionalLike<'a, '_> {
         write!(f, [soft_line_break_or_space(), "?", space()])?;
 
         let format_consequent = format_with(|f| {
-            let format_consequent_with_trailing_comments =
-                format_once(|f| match self.conditional {
+            let format_consequent_with_trailing_comments = format_once(|f| {
+                let (start, end) = match self.conditional {
                     ConditionalLike::ConditionalExpression(conditional) => {
                         write!(f, FormatNodeWithoutTrailingComments(conditional.consequent()))?;
-                        format_trailing_comments(
-                            conditional.consequent.span().end,
-                            conditional.alternate.span().start,
-                            b':',
-                            f,
-                        )
+                        (conditional.consequent.span().end, conditional.alternate.span().start)
                     }
                     ConditionalLike::TSConditionalType(conditional) => {
                         write!(f, FormatNodeWithoutTrailingComments(conditional.true_type()))?;
-                        format_trailing_comments(
-                            conditional.true_type.span().end,
-                            conditional.false_type.span().start,
-                            b':',
-                            f,
-                        )
+                        (conditional.true_type.span().end, conditional.false_type.span().start)
                     }
-                });
+                };
+                format_trailing_comments(start, end, b':', f)
+            });
 
             let format_consequent_with_proper_indentation = format_with(|f| {
                 if f.options().indent_style.is_space() {
@@ -606,7 +591,11 @@ impl<'a> Format<'a> for FormatConditionalLike<'a, '_> {
         });
 
         let grouped = format_with(|f| {
-            if layout.is_root() { write!(f, [group(&format_inner)]) } else { format_inner.fmt(f) }
+            if layout.is_root() || layout.is_nested_test() {
+                write!(f, [group(&format_inner)])
+            } else {
+                format_inner.fmt(f)
+            }
         });
 
         if layout.is_nested_test() || should_extra_indent {

crates/oxc_formatter/tests/fixtures/ts/conditional-type/nested-test.ts

@@ -0,0 +1,12 @@
+type IsUnion<T> = (
+  Testtttttttttttttttttttttttttttttttttt extends any ? false : never
+) extends false
+  ? false
+  : true
+
+
+
+export const IsUnionType = (
+  Testtttttttttttttttttttttttttttttttttt ? false : never
+)  ? false
+  : true

crates/oxc_formatter/tests/fixtures/ts/conditional-type/nested-test.ts.snap

@@ -0,0 +1,30 @@
+---
+source: crates/oxc_formatter/tests/fixtures/mod.rs
+---
+==================== Input ====================
+type IsUnion<T> = (
+  Testtttttttttttttttttttttttttttttttttt extends any ? false : never
+) extends false
+  ? false
+  : true
+
+
+
+export const IsUnionType = (
+  Testtttttttttttttttttttttttttttttttttt ? false : never
+)  ? false
+  : true
+==================== Output ====================
+type IsUnion<T> = (
+  Testtttttttttttttttttttttttttttttttttt extends any ? false : never
+) extends false
+  ? false
+  : true;
+
+export const IsUnionType = (
+  Testtttttttttttttttttttttttttttttttttt ? false : never
+)
+  ? false
+  : true;
+
+===================== End =====================