1 files changed, 56 insertions, 0 deletions
diff --git a/preact/compat/test/ts/memo.tsx b/preact/compat/test/ts/memo.tsx
new file mode 100644
index 0000000..4e89e26
--- /dev/null
+++ b/preact/compat/test/ts/memo.tsx
@@ -0,0 +1,56 @@
+import * as React from '../../src';
+import { expectType } from './utils';
+
+interface MemoProps {
+	required: string;
+	optional?: string;
+	defaulted: string;
+}
+
+interface MemoPropsExceptDefaults {
+	required: string;
+	optional?: string;
+}
+
+const ComponentExceptDefaults = () => <div></div>;
+
+const ReadonlyBaseComponent = (props: Readonly<MemoProps>) => (
+	<div>{props.required + props.optional + props.defaulted}</div>
+);
+ReadonlyBaseComponent.defaultProps = { defaulted: '' };
+
+const BaseComponent = (props: MemoProps) => (
+	<div>{props.required + props.optional + props.defaulted}</div>
+);
+BaseComponent.defaultProps = { defaulted: '' };
+
+// memo for readonly component with default comparison
+const MemoedReadonlyComponent = React.memo(ReadonlyBaseComponent);
+expectType<React.FunctionComponent<MemoProps>>(MemoedReadonlyComponent);
+export const memoedReadonlyComponent = (
+	<MemoedReadonlyComponent required="hi" />
+);
+
+// memo for non-readonly component with default comparison
+const MemoedComponent = React.memo(BaseComponent);
+expectType<React.FunctionComponent<MemoProps>>(MemoedComponent);
+export const memoedComponent = <MemoedComponent required="hi" />;
+
+// memo with custom comparison
+const CustomMemoedComponent = React.memo(BaseComponent, (a, b) => {
+	expectType<MemoProps>(a);
+	expectType<MemoProps>(b);
+	return a.required === b.required;
+});
+expectType<React.FunctionComponent<MemoProps>>(CustomMemoedComponent);
+export const customMemoedComponent = <CustomMemoedComponent required="hi" />;
+
+const MemoedComponentExceptDefaults = React.memo<MemoPropsExceptDefaults>(
+	ComponentExceptDefaults
+);
+expectType<React.FunctionComponent<MemoPropsExceptDefaults>>(
+	MemoedComponentExceptDefaults
+);
+export const memoedComponentExceptDefaults = (
+	<MemoedComponentExceptDefaults required="hi" />
+);