Create custom asymmetric matcher to test if a value is between two nu…

…mbers

__tests__/customMatchers.ts

@@ -0,0 +1,43 @@
+import { expect } from '@jest/globals';
+
+const TIMED_OUT = Symbol();
+
+function timeout(ms: number) {
+  return new Promise<typeof TIMED_OUT>((resolve) => {
+    setTimeout(() => resolve(TIMED_OUT), ms);
+  });
+}
+
+expect.extend({
+  async toSettle(testPromise: Promise<unknown>, ms: number) {
+    const promise = await Promise.race([testPromise, timeout(ms)]);
+    const isExpectedResult = promise !== TIMED_OUT;
+
+    if (isExpectedResult) {
+      return {
+        message: () => `Expected promise not to settle`,
+        pass: true,
+      };
+    }
+
+    return {
+      message: () => `Expected promise to settle, but timed out after ${ms}ms`,
+      pass: false,
+    };
+  },
+  numberBetween(received: number, argumentOne: number, argumentTwo: number) {
+    if (argumentOne > argumentTwo) {
+      // Switch values
+      [argumentOne, argumentTwo] = [argumentTwo, argumentOne];
+    }
+
+    const pass = received >= argumentOne && received <= argumentTwo;
+
+    return {
+      pass,
+      message: pass
+        ? () => `expected ${received} not to be between ${argumentOne} and ${argumentTwo}`
+        : () => `expected ${received} to be between ${argumentOne} and ${argumentTwo}`,
+    };
+  },
+});