fix: allow abstract constructor signatures for hasMixin

#57
tannerntannern · Feb 8, 2023 · 8964b59 · 8964b59
2 parents a953406 + 5b7722b
commit 8964b59
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Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/src/mixin-tracking.ts b/src/mixin-tracking.ts
@@ -10,7 +10,7 @@ export const getMixinsForClass = (clazz: Class) =>
 export const registerMixins = (mixedClass: any, constituents: Function[]) =>
 	mixins.set(mixedClass, constituents);
 
-export const hasMixin = <M>(instance: any, mixin: new (...args) => M): instance is M => {
+export const hasMixin = <M>(instance: any, mixin: abstract new (...args) => M): instance is M => {
 	if (instance instanceof mixin)
 		return true;
 

diff --git a/test/integration/has-mixin.test.ts b/test/integration/has-mixin.test.ts
@@ -26,6 +26,13 @@ describe('hasMixin(...)', () => {
 			expect(hasMixin(fooBar, Bar)).to.be.true;
 		});
 
+		it('should work with abstract classes', () => {
+			abstract class Baz {}
+			class FooBaz extends Mixin(Foo, Baz) {}
+			const fooBaz: any = new FooBaz();
+			expect(hasMixin(fooBaz, Baz)).to.be.true;
+		});
+
 		it('should work for cases where the mixin is buried deep in the proto chain', () => {
 			class Foo1 {}
 			class Bar1 {}