Testing Helpers: Mock Server

The mock server provides several methods to help verify that your requests were made as expected.

Verifying Route Calls

Tracking which routes have been called is a key part of many tests. The mock server provides several methods and properties to help with this.

`allRoutesCalled()`

The allRoutesCalled() method checks if all routes have been called. It returns true if all routes have been called at least once, and false otherwise:

import { MockServer, FetchMocker } from "mentoss";

const server = new MockServer("https://api.example.com");
const mocker = new FetchMocker({ servers: [server] });

server.get("/users", 200);
server.post("/users", 200);

console.log(server.allRoutesCalled()); // false

await mocker.fetch("https://api.example.com/users");
console.log(server.allRoutesCalled()); // false

await mocker.fetch("https://api.example.com/users", { method: "POST" });
console.log(server.allRoutesCalled()); // true

In this example, the allRoutesCalled() method first returns false because neither the GET nor the POST /users route has been called yet. After both routes have been called, the method returns true.

`assertAllRoutesCalled()`

The assertAllRoutesCalled() method is an assertion that checks if all routes have been called. It throws an error if any routes have not been called:

import { MockServer, FetchMocker } from "mentoss";

const server = new MockServer("https://api.example.com");
const mocker = new FetchMocker({ servers: [server] });

server.get("/users", 200);
server.post("/users", 200);

await mocker.fetch("https://api.example.com/users");
server.assertAllRoutesCalled(); // Error!

The thrown error contains a message with information about the uncalled routes.

`called()`

The called() method checks if a specific route has been called. You can pass either a URL string (which defaults to a GET request) or a request pattern object:

import { MockServer, FetchMocker } from "mentoss";

const server = new MockServer("https://api.example.com");
const mocker = new FetchMocker({ servers: [server] });

server.post(
  {
    url: "/users",
    body: {
      name: "John Doe",
    },
  },
  200,
);

console.log(server.called("/users")); // false

await mocker.fetch("https://api.example.com/users", {
    method: "POST",
    body: {
        name: "John Doe",
    },
});

console.log(server.called("/users")); // true

console.log(server.called({
    url: "/users",
    method: "POST",
    body: {
        name: "John Doe",
    },
})); // true

In this example, the called() method returns false because the /users route has not been called yet. The matching is done using the same comparison logic as if a fetch() request was made to the route.

`uncalledRoutes`

The uncalledRoutes property returns an array with information about uncalled routes. You can use this property to check if any routes have not been called:

import { MockServer, FetchMocker } from "mentoss";

const server = new MockServer("https://api.example.com");
const mocker = new FetchMocker({ servers: [server] });

server.get("/users", 200);
server.post("/users", 200);

await mocker.fetch("https://api.example.com/users");

console.log(server.uncalledRoutes); // ["🚧 [Route: POST https://api.example.com/users -> 200]"]

The uncalledRoutes property is helpful when you want to format your own error messages or assertions.

Additional Helpers

`clear()`

The clear() method removes all routes from the server so you can reuse the same server for multiple tests.

import { MockServer, FetchMocker } from "mentoss";

const server = new MockServer("https://api.example.com");
const mocker = new FetchMocker({ servers: [server] });

server.get("/users", 200);

server.clear();

await mocker.fetch("https://api.example.com/users"); // Error!