Print parens around type assertion as LHS in assignment, fixes #2521 (#2525)

src/fast-path.js

@@ -304,6 +304,13 @@ FastPath.prototype.needsParens = function(options) {
         case "MemberExpression":
           return name === "object" && parent.object === node;
 
+        case "AssignmentExpression":
+          return (
+            parent.left === node &&
+            (node.type === "TSTypeAssertionExpression" ||
+              node.type === "TSAsExpression")
+          );
+
         case "BinaryExpression":
         case "LogicalExpression": {
           if (!node.operator && node.type !== "TSTypeAssertionExpression") {

tests/typescript_as/__snapshots__/jsfmt.spec.js.snap

@@ -21,6 +21,8 @@ const state = JSON.stringify({
   next: window.location.href,
   nonce,
 } as State);
+
+(foo.bar as Baz) = [bar];
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 const name = (description as DescriptionObject).name || (description as string);
 this.isTabActionBar((e.target || e.srcElement) as HTMLElement);
@@ -47,4 +49,6 @@ const state = JSON.stringify({
   nonce
 } as State);
 
+(foo.bar as Baz) = [bar];
+
 `;

tests/typescript_as/as.js

@@ -18,3 +18,5 @@ const state = JSON.stringify({
   next: window.location.href,
   nonce,
 } as State);
+
+(foo.bar as Baz) = [bar];

tests/typescript_cast/__snapshots__/jsfmt.spec.js.snap

@@ -51,6 +51,7 @@ exports[`parenthesis.ts 1`] = `
 <x>a && [];
 true || <x>a;
 <x>a + <x>b;
+(<x>a) = 1;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 <DocumentHighlightKind>(a ? b : c);
 <any>(() => {});
@@ -59,5 +60,6 @@ true || <x>a;
 <x>a && [];
 true || <x>a;
 <x>a + <x>b;
+(<x>a) = 1;
 
 `;

tests/typescript_cast/parenthesis.ts

@@ -5,3 +5,4 @@
 <x>a && [];
 true || <x>a;
 <x>a + <x>b;
+(<x>a) = 1;