Add typechecking test cases

src/__tests__/types.tsx

@@ -0,0 +1,284 @@
+/** @jsx createElement */
+/* eslint @typescript-eslint/no-unused-vars: "off", jest/expect-expect: "off" */
+import {
+	createElement,
+	Component,
+	FunctionComponent,
+	Context,
+	GeneratorComponent,
+} from "..";
+
+describe("types", () => {
+	type MyProps = {
+		message: string;
+	};
+	let elem: any;
+
+	test("Not Components", () => {
+		// @ts-expect-error
+		const MyString: Component = "Hello";
+
+		// @ts-expect-error
+		const MyNumber: Component = 10;
+
+		// @ts-expect-error
+		const MyBoolean: Component = true;
+
+		// @ts-expect-error
+		const MyNull: Component = null;
+
+		// @ts-expect-error
+		const MyUndefined: Component = undefined;
+
+		// Not entirely sure why this one doesn't error anymore. seems that <a></a> returns
+		// any, while createElement('a') returns Element<any>.
+		// skip @ts-expect-error
+		// const MyElement: Component = <a></a>;
+
+		// @ts-expect-error
+		const NotComponent: Component = {};
+	});
+
+	test("Components", () => {
+		const MyFunctionComponent: Component<MyProps> = function (this, props) {
+			const ctx: Context<MyProps> = this;
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyFunctionComponent />;
+		elem = <MyFunctionComponent message={"message"} />;
+
+		const MyAsyncFunctionComponent: Component<MyProps> = async function (
+			this,
+			props,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyAsyncFunctionComponent />;
+		elem = <MyAsyncFunctionComponent message={"message"} />;
+
+		const MyGeneratorComponent: Component<MyProps> = function* (
+			this,
+			initialProps,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = initialProps.message;
+			// @ts-expect-error
+			let unexpected = initialProps.unexpected;
+
+			for (const newProps of this) {
+				let newMessage: string = initialProps.message;
+				// @ts-expect-error
+				let newUnexpected = newProps.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyGeneratorComponent />;
+		elem = <MyGeneratorComponent message={"message"} />;
+
+		const MyAsyncGeneratorComponent: Component<MyProps> = async function* (
+			this,
+			initialProps,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = initialProps.message;
+			// @ts-expect-error
+			let unexpected = initialProps.unexpected;
+
+			for await (const newProps of this) {
+				let newMessage: string = initialProps.message;
+				// @ts-expect-error
+				let newUnexpected = newProps.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyAsyncGeneratorComponent />;
+		elem = <MyAsyncGeneratorComponent message={"message"} />;
+	});
+
+	test("Function Components", () => {
+		const MyFunctionComponent: FunctionComponent<MyProps> = function (
+			this,
+			props,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyFunctionComponent />;
+		elem = <MyFunctionComponent message={"message"} />;
+
+		const MyAsyncFunctionComponent: FunctionComponent<MyProps> = async function (
+			this,
+			props,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyAsyncFunctionComponent />;
+		elem = <MyAsyncFunctionComponent message={"message"} />;
+
+		// @ts-expect-error
+		const MyGeneratorComponent: FunctionComponent<MyProps> = function* (
+			this,
+			props,
+		) {
+			yield <div></div>;
+		};
+		// @ts-expect-error
+		const MyAsyncGeneratorComponent: FunctionComponent<MyProps> = async function* (
+			this,
+			props,
+		) {
+			yield <div></div>;
+		};
+	});
+
+	test("Generator Components", () => {
+		const MyGeneratorComponent: GeneratorComponent<MyProps> = function* (
+			this,
+			initialProps,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = initialProps.message;
+			// @ts-expect-error
+			let unexpected = initialProps.unexpected;
+
+			for (const newProps of this) {
+				let newMessage: string = initialProps.message;
+				// @ts-expect-error
+				let newUnexpected = newProps.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyGeneratorComponent />;
+		elem = <MyGeneratorComponent message={"message"} />;
+
+		const MyAsyncGeneratorComponent: GeneratorComponent<MyProps> = async function* (
+			this,
+			initialProps,
+		) {
+			const ctx: Context<MyProps> = this;
+			let message: string = initialProps.message;
+			// @ts-expect-error
+			let unexpected = initialProps.unexpected;
+
+			for await (const newProps of this) {
+				let newMessage: string = initialProps.message;
+				// @ts-expect-error
+				let newUnexpected = newProps.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		};
+		// @ts-expect-error
+		elem = <MyAsyncGeneratorComponent />;
+		elem = <MyAsyncGeneratorComponent message={"message"} />;
+
+		// TODO: add ts-expect-error at some point in the future, I guess?
+		// This will not pass because the function is infered as any, and any matches Iterator<any, any, any>.
+		// Hopefully a later typescript version fixes this :(
+		const MyFunctionComponent: GeneratorComponent<MyProps> = function (
+			this,
+			props,
+		) {
+			return <div></div>;
+		};
+		// @ts-expect-error
+		const MyAsyncFunctionComponent: GeneratorComponent<MyProps> = async function (
+			this,
+			props,
+		) {
+			return <div></div>;
+		};
+	});
+
+	test("Loose Typings", () => {
+		function MyFunctionComponent(props: MyProps) {
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		}
+		// @ts-expect-error
+		elem = <MyFunctionComponent />;
+		elem = <MyFunctionComponent message={"message"} />;
+
+		async function MyAsyncFunctionComponent(props: MyProps) {
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			return <div></div>;
+		}
+		// @ts-expect-error
+		elem = <MyAsyncFunctionComponent />;
+		elem = <MyAsyncFunctionComponent message={"message"} />;
+
+		function* MyGeneratorComponent(this: Context, props: MyProps) {
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			for (props of this) {
+				let newMessage: string = props.message;
+				// @ts-expect-error
+				let newUnexpected = props.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		}
+		// @ts-expect-error
+		elem = <MyGeneratorComponent />;
+		elem = <MyGeneratorComponent message={"message"} />;
+
+		async function* MyAsyncGeneratorComponent(this: Context, props: MyProps) {
+			let message: string = props.message;
+			// @ts-expect-error
+			let unexpected = props.unexpected;
+
+			for await (props of this) {
+				let newMessage: string = props.message;
+				// @ts-expect-error
+				let newUnexpected = props.unexpected;
+				yield <div></div>;
+			}
+
+			return <div></div>;
+		}
+		// @ts-expect-error
+		elem = <MyAsyncGeneratorComponent />;
+		elem = <MyAsyncGeneratorComponent message={"message"} />;
+	});
+});