Fix #115: typeof usage on object types

src/transform-inline/visitor-utils.ts

@@ -71,7 +71,14 @@ export function getPropertyInfo(parentType: ts.Type, symbol: ts.Symbol, visitorC
     let isFunction: boolean | undefined = undefined;
     let optional: boolean | undefined = undefined;
 
-    if ('valueDeclaration' in symbol) {
+    if ('type' in symbol) {
+        // Attempt to get it from 'type'
+
+        propertyType = (symbol as { type?: ts.Type }).type;
+        isMethod = false;
+        isFunction = false;
+        optional = ((symbol as ts.Symbol).flags & ts.SymbolFlags.Optional) !== 0;
+    } else if ('valueDeclaration' in symbol) {
         // Attempt to get it from 'valueDeclaration'
 
         const valueDeclaration = symbol.valueDeclaration;
@@ -94,13 +101,6 @@ export function getPropertyInfo(parentType: ts.Type, symbol: ts.Symbol, visitorC
             propertyType = visitorContext.checker.getTypeFromTypeNode(valueDeclaration.type);
         }
         optional = !!valueDeclaration.questionToken;
-    } else if ('type' in symbol) {
-        // Attempt to get it from 'type'
-
-        propertyType = (symbol as { type?: ts.Type }).type;
-        isMethod = false;
-        isFunction = false;
-        optional = ((symbol as ts.Symbol).flags & ts.SymbolFlags.Optional) !== 0;
     } else if ('getTypeOfPropertyOfType' in visitorContext.checker) {
         // Attempt to get it from 'visitorContext.checker.getTypeOfPropertyOfType'
 

test/issue-115.ts

@@ -0,0 +1,37 @@
+import * as assert from 'assert';
+import { is } from '../index';
+
+/* https://github.com/woutervh-/typescript-is/issues/115 */
+
+export const Status = {
+    enable: 'enable',
+    disable: 'disable'
+} as const;
+
+type StatusObject<Key extends keyof typeof Status> = {
+    status: (typeof Status)[Key];
+};
+
+const testObj = {
+    outer: 0
+};
+
+describe('is', () => {
+    describe('Accessing generic member of a type', () => {
+        it('should return true for the right member', () => {
+            assert.deepStrictEqual(is<StatusObject<'enable'>>({ status: Status.enable }), true);
+        });
+        it('should return false for the wrong member', () => {
+           assert.deepStrictEqual(is<StatusObject<'enable'>>({ status: Status.disable }), false);
+        });
+    });
+
+    describe('Using typeof instead of a type', () => {
+        it('should return true for the right member', () => {
+            assert.deepStrictEqual(is<typeof testObj>('test'), false);
+        });
+        it('should return false for the wrong member', () => {
+           assert.deepStrictEqual(is<typeof testObj>({ outer: 5 }), true);
+        });
+    });
+});