wait-for

Wait for is a testing utility used for when a test needs to wait for a condition to become true. It will repeadely call a function until the supplied condition becomes true.

Installation

Install with npm install --save @bmanley91/wait-for

Usage

waitFor is called with three parameters:

• call - The function to call. This function can be async.
• condition - A syncronous function that returns a boolean.
• ms - The number of miliseconds to wait before timing out.

waitFor resolves to the return value of call if the expected condition is met. Otherwise it rejects with a Timeout Error.

Example

The following code will repeatedly call makeRestCall until a status code of 429 is returned or 30 seconds has passed.

async function makeRestCall() {
    // Make a call to an external API.
    // Returns a body with a status code.
}

const expectedStatusCode = 429;
const result = await waitFor(
    makeRestCall,
    body => body.statusCode === expectedStatusCode,
    30000
);

To call a function with the same parameters repeatedly, an arrow function containing the function to be called can be used.

async function makeRestCall(url, body) {
    // Make a call to an external API.
    // Returns a body with a status code.
}

const targetUrl = "foo.bar"
const body = { param: "thing" };

const expectedStatusCode = 429;
const result = await waitFor(
    async () => makeRestCall(targetUrl, body),
    body => body.statusCode === expectedStatusCode,
    30000
);

Publishing Changes

To publish changes increment the version number appropriately. Then, run npm publish. NPM will automattically run the prepublish script to assure the code compiles and that tests pass.