feat: configurable default timeout and interval (#18)

* feat: configurable default timeout and interval

* chore: fix prettier

Author: mmkal

README.md

@@ -161,6 +161,14 @@ waitForExpect takes 3 arguments, 2 optional.
  */
 ```
 
+The defaults for `timeout` and `interval` can also be edited globally, e.g. in a jest setup file:
+```javascript
+import waitForExpect from 'wait-for-expect';
+
+waitForExpect.defaults.timeout = 2000;
+waitForExpect.defaults.interval = 10;
+```
+
 ## Changelog
 1.0.0 - 15 June 2018
 

src/index.ts

@@ -13,6 +13,11 @@ declare global {
 const { setTimeout, Date: { now } } =
   typeof window !== "undefined" ? window : global;
 
+const defaults = {
+  timeout: 4500,
+  interval: 50
+};
+
 /**
  * Waits for the expectation to pass and returns a Promise
  *
@@ -23,8 +28,8 @@ const { setTimeout, Date: { now } } =
  */
 const waitForExpect = function waitForExpect(
   expectation: () => void,
-  timeout = 4500,
-  interval = 50
+  timeout = defaults.timeout,
+  interval = defaults.interval
 ) {
   const startTime = now();
   return new Promise((resolve, reject) => {
@@ -49,4 +54,4 @@ const waitForExpect = function waitForExpect(
   });
 };
 
-export default waitForExpect;
+export default Object.assign(waitForExpect, { defaults });

src/waitForExpect.spec.ts

@@ -2,6 +2,11 @@
 import "./toBeInRangeMatcher";
 import waitForExpect from "./index";
 
+const originalDefaults = { ...waitForExpect.defaults };
+beforeEach(() => {
+  Object.assign(waitForExpect.defaults, originalDefaults);
+});
+
 test("it waits for expectation to pass", async () => {
   let numberToChange = 10;
   // we are using random timeout here to simulate a real-time example
@@ -81,6 +86,23 @@ test("it reruns the expectation every x ms, as provided with the second argument
   }
 });
 
+test("it reruns the expectation every x ms, as provided by the default timeout and interval", async () => {
+  const timeout = 600;
+  const interval = 150;
+  waitForExpect.defaults.timeout = timeout;
+  waitForExpect.defaults.interval = interval;
+  const mockExpectation = jest.fn();
+  mockExpectation.mockImplementation(() => expect(true).toEqual(false));
+  try {
+    await waitForExpect(mockExpectation);
+    throw Error("waitForExpect should have thrown");
+  } catch (e) {
+    // initial run + reruns
+    const expectedTimesToRun = 1 + Math.floor(timeout / interval);
+    expect(mockExpectation).toHaveBeenCalledTimes(expectedTimesToRun);
+  }
+});
+
 test("it works with promises", async () => {
   let numberToChange = 10;
   const randomTimeout = Math.floor(Math.random() * 300);