feat(expect): add asymmetric matchers (any, anything, arrayContaining) (

#4366)

expect/_any_test.ts

@@ -0,0 +1,15 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+
+class Cat {}
+Deno.test("expect.any()", () => {
+  expect(new Cat()).toEqual(expect.any(Cat));
+  expect(new Cat()).toEqual(expect.any(Object));
+  expect("Hello").toEqual(expect.any(String));
+  expect(1).toEqual(expect.any(Number));
+  expect(() => {}).toEqual(expect.any(Function));
+  expect(false).toEqual(expect.any(Boolean));
+  expect(BigInt(1)).toEqual(expect.any(BigInt));
+  expect(Symbol("sym")).toEqual(expect.any(Symbol));
+});

expect/_anything_test.ts

@@ -0,0 +1,27 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+import { AssertionError, assertThrows } from "../assert/mod.ts";
+import { fn } from "./fn.ts";
+
+Deno.test("expect.anything() as a parameter of toEqual()", () => {
+  expect(null).not.toEqual(expect.anything());
+  expect(undefined).not.toEqual(expect.anything());
+  expect(1).toEqual(expect.anything());
+
+  assertThrows(() => {
+    expect(null).toEqual(expect.anything());
+  }, AssertionError);
+  assertThrows(() => {
+    expect(undefined).toEqual(expect.anything());
+  }, AssertionError);
+  assertThrows(() => {
+    expect(1).not.toEqual(expect.anything());
+  }, AssertionError);
+});
+
+Deno.test("expect.anything() as a parameter of toHaveBeenCalled()", () => {
+  const mockFn = fn();
+  mockFn(3);
+  expect(mockFn).toHaveBeenCalledWith(expect.anything());
+});

expect/_array_containing_test.ts

@@ -0,0 +1,16 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+
+Deno.test("expect.arrayContaining() with array of numbers", () => {
+  const arr = [1, 2, 3];
+  expect([1, 2, 3, 4]).toEqual(expect.arrayContaining(arr));
+  expect([4, 5, 6]).not.toEqual(expect.arrayContaining(arr));
+  expect([1, 2, 3]).toEqual(expect.arrayContaining(arr));
+});
+
+Deno.test("expect.arrayContaining() with array of mixed types", () => {
+  const arr = [1, 2, "hello"];
+  expect([1, 2, 3, "hello", "bye"]).toEqual(expect.arrayContaining(arr));
+  expect([4, "bye"]).not.toEqual(expect.arrayContaining(arr));
+});

expect/_asymmetric_matchers.ts

@@ -0,0 +1,79 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+// deno-lint-ignore-file no-explicit-any
+
+abstract class AsymmetricMatcher<T> {
+  constructor(
+    protected value: T,
+  ) {}
+  abstract equals(other: unknown): boolean;
+}
+
+export class Anything extends AsymmetricMatcher<void> {
+  equals(other: unknown): boolean {
+    return other !== null && other !== undefined;
+  }
+}
+
+export function anything(): Anything {
+  return new Anything();
+}
+
+export class Any extends AsymmetricMatcher<any> {
+  constructor(value: unknown) {
+    if (value === undefined) {
+      throw TypeError("Expected a constructor function");
+    }
+    super(value);
+  }
+  equals(other: unknown): boolean {
+    if (typeof other === "object") {
+      return other instanceof this.value;
+    } else {
+      if (this.value == Number) {
+        return typeof other === "number";
+      }
+
+      if (this.value == String) {
+        return typeof other == "string";
+      }
+
+      if (this.value == Number) {
+        return typeof other == "number";
+      }
+
+      if (this.value == Function) {
+        return typeof other == "function";
+      }
+
+      if (this.value == Boolean) {
+        return typeof other == "boolean";
+      }
+
+      if (this.value == BigInt) {
+        return typeof other == "bigint";
+      }
+
+      if (this.value == Symbol) {
+        return typeof other == "symbol";
+      }
+    }
+    return false;
+  }
+}
+
+export function any(c: unknown): Any {
+  return new Any(c);
+}
+
+export class ArrayContaining extends AsymmetricMatcher<any[]> {
+  constructor(arr: any[]) {
+    super(arr);
+  }
+  equals(other: any[]): boolean {
+    return this.value.every((e) => other.includes(e));
+  }
+}
+
+export function arrayContaining(c: any[]): ArrayContaining {
+  return new ArrayContaining(c);
+}

expect/_equal.ts

@@ -3,6 +3,7 @@
 // This file is copied from `std/assert`.
 
 import type { EqualOptions } from "./_types.ts";
+import { Any, Anything, ArrayContaining } from "./_asymmetric_matchers.ts";
 
 function isKeyedCollection(x: unknown): x is Set<unknown> {
   return [Symbol.iterator, "size"].every((k) => k in (x as Set<unknown>));
@@ -52,6 +53,15 @@ export function equal(c: unknown, d: unknown, options?: EqualOptions): boolean {
     ) {
       return String(a) === String(b);
     }
+    if (b instanceof Anything) {
+      return b.equals(a);
+    }
+    if (b instanceof Any) {
+      return b.equals(a);
+    }
+    if (b instanceof ArrayContaining && a instanceof Array) {
+      return b.equals(a);
+    }
     if (a instanceof Date && b instanceof Date) {
       const aTime = a.getTime();
       const bTime = b.getTime();
@@ -95,7 +105,7 @@ export function equal(c: unknown, d: unknown, options?: EqualOptions): boolean {
       if (!strictCheck) {
         if (aLen > 0) {
           for (let i = 0; i < aKeys.length; i += 1) {
-            const key = aKeys[i];
+            const key = aKeys[i]!;
             if (
               (key in a) && (a[key as keyof typeof a] === undefined) &&
               !(key in b)
@@ -107,7 +117,7 @@ export function equal(c: unknown, d: unknown, options?: EqualOptions): boolean {
 
         if (bLen > 0) {
           for (let i = 0; i < bKeys.length; i += 1) {
-            const key = bKeys[i];
+            const key = bKeys[i]!;
             if (
               (key in b) && (b[key as keyof typeof b] === undefined) &&
               !(key in a)

expect/expect.ts

@@ -47,6 +47,7 @@ import {
   toThrow,
 } from "./_matchers.ts";
 import { isPromiseLike } from "./_utils.ts";
+import { any, anything, arrayContaining } from "./_asymmetric_matchers.ts";
 
 const matchers: Record<MatcherKey, Matcher> = {
   lastCalledWith: toHaveBeenLastCalledWith,
@@ -168,3 +169,6 @@ export function expect(value: unknown, customMessage?: string): Expected {
 }
 
 expect.addEqualityTesters = addCustomEqualityTesters;
+expect.anything = anything;
+expect.any = any;
+expect.arrayContaining = arrayContaining;