Fix formatting of conditional types (#21762)

* Add test for formatting of conditional types

* Fix formatting of conditional types

Author: lankaapura

src/services/formatting/rules.ts

@@ -409,6 +409,7 @@ namespace ts.formatting {
         switch (context.contextNode.kind) {
             case SyntaxKind.BinaryExpression:
             case SyntaxKind.ConditionalExpression:
+            case SyntaxKind.ConditionalType:
             case SyntaxKind.AsExpression:
             case SyntaxKind.ExportSpecifier:
             case SyntaxKind.ImportSpecifier:
@@ -461,7 +462,8 @@ namespace ts.formatting {
     }
 
     function isConditionalOperatorContext(context: FormattingContext): boolean {
-        return context.contextNode.kind === SyntaxKind.ConditionalExpression;
+        return context.contextNode.kind === SyntaxKind.ConditionalExpression ||
+                context.contextNode.kind === SyntaxKind.ConditionalType;
     }
 
     function isSameLineTokenOrBeforeBlockContext(context: FormattingContext): boolean {

tests/cases/fourslash/formattingConditionalOperator.ts

@@ -3,4 +3,4 @@
 ////var x=true?1:2
 format.document();
 goTo.bof();
-verify.currentLineContentIs("var x = true ? 1 : 2");;
+verify.currentLineContentIs("var x = true ? 1 : 2");

tests/cases/fourslash/formattingConditionalTypes.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts'/>
+
+/////*L1*/type Diff1<T, U> = T extends U?never:T;
+/////*L2*/type Diff2<T, U> = T    extends    U  ?    never   :     T;
+
+format.document();
+
+goTo.marker("L1");
+verify.currentLineContentIs("type Diff1<T, U> = T extends U ? never : T;");
+
+goTo.marker("L2");
+verify.currentLineContentIs("type Diff2<T, U> = T extends U ? never : T;");