fix(37431): allow only one space between async keyword and method name (#37504)

Author: a-tarasyuk

src/services/formatting/rules.ts

@@ -129,7 +129,7 @@ namespace ts.formatting {
 
             // Async-await
             rule("SpaceBetweenAsyncAndOpenParen", SyntaxKind.AsyncKeyword, SyntaxKind.OpenParenToken, [isArrowFunctionContext, isNonJsxSameLineTokenContext], RuleAction.InsertSpace),
-            rule("SpaceBetweenAsyncAndFunctionKeyword", SyntaxKind.AsyncKeyword, SyntaxKind.FunctionKeyword, [isNonJsxSameLineTokenContext], RuleAction.InsertSpace),
+            rule("SpaceBetweenAsyncAndFunctionKeyword", SyntaxKind.AsyncKeyword, [SyntaxKind.FunctionKeyword, SyntaxKind.Identifier], [isNonJsxSameLineTokenContext], RuleAction.InsertSpace),
 
             // Template string
             rule("NoSpaceBetweenTagAndTemplateString", [SyntaxKind.Identifier, SyntaxKind.CloseParenToken], [SyntaxKind.NoSubstitutionTemplateLiteral, SyntaxKind.TemplateHead], [isNonJsxSameLineTokenContext], RuleAction.DeleteSpace),

tests/cases/fourslash/formatAsyncClassMethod1.ts

@@ -0,0 +1,12 @@
+///<reference path="fourslash.ts"/>
+
+////class Foo {
+////    async     foo() {}
+////}
+
+format.document();
+verify.currentFileContentIs(
+`class Foo {
+    async foo() { }
+}`
+);

tests/cases/fourslash/formatAsyncClassMethod2.ts

@@ -0,0 +1,12 @@
+///<reference path="fourslash.ts"/>
+
+////class Foo {
+////    private    async     foo() {}
+////}
+
+format.document();
+verify.currentFileContentIs(
+`class Foo {
+    private async foo() { }
+}`
+);