Merge branch 'fix/unary-expression-parens' (benjamn#922)

lib/printer.ts

@@ -963,13 +963,17 @@ function genericPrintNoParens(path: any, options: any, print: any) {
       // Literal identifying the imported-from module.
       return fromString(nodeStr(n.value, options), options);
 
-    case "UnaryExpression":
+    case "UnaryExpression": {
       parts.push(n.operator);
+      const {argument} = path.getValue();
+      const needsParens = argument.type === 'LogicalExpression';
+      const parenLeft = needsParens ? '(' : '';
+      const parenRight = needsParens ? ')' : '';
       if (/[a-z]$/.test(n.operator)) parts.push(" ");
-      parts.push(path.call(print, "argument"));
+      parts.push(parenLeft, path.call(print, "argument"), parenRight);
       return concat(parts);
 
-    case "UpdateExpression":
+    } case "UpdateExpression":
       parts.push(path.call(print, "argument"), n.operator);
 
       if (n.prefix) parts.reverse();

package.json

@@ -48,8 +48,8 @@
     "tslib": "^2.0.1"
   },
   "devDependencies": {
-    "@babel/core": "7.11.6",
-    "@babel/parser": "^7.12.5",
+    "@babel/core": "^7.11.6",
+    "@babel/parser": "^7.11.5",
     "@babel/preset-env": "7.11.5",
     "@types/esprima": "4.0.2",
     "@types/glob": "7.1.3",

test/babel.ts

@@ -502,4 +502,16 @@ describe("Babel", function () {
       ["class A {", "  declare public readonly x;", "}"].join(eol),
     );
   });
+
+  it("should keep braces in !(a && b)", function () {
+    const code = '(options || !options.bidirectional) ? false : true;';
+    const ast = recast.parse(code, parseOptions);
+
+    ast.program.body[0].expression = b.unaryExpression('!', ast.program.body[0].expression.test);
+
+    assert.strictEqual(
+      recast.print(ast).code,
+      '!(options || !options.bidirectional);',
+    );
+  });
 });