add: unit and integration testing

app/node_modules/p-try/index.d.ts

@@ -0,0 +1,39 @@
+declare const pTry: {
+	/**
+	Start a promise chain.
+
+	@param fn - The function to run to start the promise chain.
+	@param arguments - Arguments to pass to `fn`.
+	@returns The value of calling `fn(...arguments)`. If the function throws an error, the returned `Promise` will be rejected with that error.
+
+	@example
+	```
+	import pTry = require('p-try');
+
+	(async () => {
+		try {
+			const value = await pTry(() => {
+				return synchronousFunctionThatMightThrow();
+			});
+			console.log(value);
+		} catch (error) {
+			console.error(error);
+		}
+	})();
+	```
+	*/
+	<ValueType, ArgumentsType extends unknown[]>(
+		fn: (...arguments: ArgumentsType) => PromiseLike<ValueType> | ValueType,
+		...arguments: ArgumentsType
+	): Promise<ValueType>;
+
+	// TODO: remove this in the next major version, refactor the whole definition to:
+	// declare function pTry<ValueType, ArgumentsType extends unknown[]>(
+	//	fn: (...arguments: ArgumentsType) => PromiseLike<ValueType> | ValueType,
+	//	...arguments: ArgumentsType
+	// ): Promise<ValueType>;
+	// export = pTry;
+	default: typeof pTry;
+};
+
+export = pTry;