feat(expect): add expect.{closeTo, stringContaining, stringMatching} (#4508)

expect/_asymmetric_matchers.ts

@@ -1,7 +1,7 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 // deno-lint-ignore-file no-explicit-any
 
-abstract class AsymmetricMatcher<T> {
+export abstract class AsymmetricMatcher<T> {
   constructor(
     protected value: T,
   ) {}
@@ -21,10 +21,11 @@ export function anything(): Anything {
 export class Any extends AsymmetricMatcher<any> {
   constructor(value: unknown) {
     if (value === undefined) {
-      throw TypeError("Expected a constructor function");
+      throw new TypeError("Expected a constructor function");
     }
     super(value);
   }
+
   equals(other: unknown): boolean {
     if (typeof other === "object") {
       return other instanceof this.value;
@@ -69,11 +70,78 @@ export class ArrayContaining extends AsymmetricMatcher<any[]> {
   constructor(arr: any[]) {
     super(arr);
   }
+
   equals(other: any[]): boolean {
-    return this.value.every((e) => other.includes(e));
+    return Array.isArray(other) && this.value.every((e) => other.includes(e));
   }
 }
 
 export function arrayContaining(c: any[]): ArrayContaining {
   return new ArrayContaining(c);
 }
+
+export class CloseTo extends AsymmetricMatcher<number> {
+  readonly #precision: number;
+
+  constructor(num: number, precision: number = 2) {
+    super(num);
+    this.#precision = precision;
+  }
+
+  equals(other: number): boolean {
+    if (typeof other !== "number") {
+      return false;
+    }
+
+    if (
+      (this.value === Number.POSITIVE_INFINITY &&
+        other === Number.POSITIVE_INFINITY) ||
+      (this.value === Number.NEGATIVE_INFINITY &&
+        other === Number.NEGATIVE_INFINITY)
+    ) {
+      return true;
+    }
+
+    return Math.abs(this.value - other) < Math.pow(10, -this.#precision) / 2;
+  }
+}
+
+export function closeTo(num: number, numDigits?: number): CloseTo {
+  return new CloseTo(num, numDigits);
+}
+
+export class StringContaining extends AsymmetricMatcher<string> {
+  constructor(str: string) {
+    super(str);
+  }
+
+  equals(other: string): boolean {
+    if (typeof other !== "string") {
+      return false;
+    }
+
+    return other.includes(this.value);
+  }
+}
+
+export function stringContaining(str: string): StringContaining {
+  return new StringContaining(str);
+}
+
+export class StringMatching extends AsymmetricMatcher<RegExp> {
+  constructor(pattern: string | RegExp) {
+    super(new RegExp(pattern));
+  }
+
+  equals(other: string): boolean {
+    if (typeof other !== "string") {
+      return false;
+    }
+
+    return this.value.test(other);
+  }
+}
+
+export function stringMatching(pattern: string | RegExp): StringMatching {
+  return new StringMatching(pattern);
+}

expect/_close_to_test.ts

@@ -0,0 +1,21 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+
+Deno.test("expect.closeTo()", () => {
+  expect(0.1 + 0.2).toEqual(expect.closeTo(0.3));
+  expect(Math.PI).toEqual(expect.closeTo(3.14));
+  expect(Number.POSITIVE_INFINITY).toEqual(
+    expect.closeTo(Number.POSITIVE_INFINITY),
+  );
+  expect(Number.NEGATIVE_INFINITY).toEqual(
+    expect.closeTo(Number.NEGATIVE_INFINITY),
+  );
+
+  expect(0.1 + 0.2).not.toEqual(expect.closeTo(0.3, 17));
+  expect(0.999_999).not.toEqual(expect.closeTo(1, 10));
+  expect(NaN).not.toEqual(expect.closeTo(NaN));
+  expect(Number.POSITIVE_INFINITY).not.toEqual(
+    expect.closeTo(Number.NEGATIVE_INFINITY),
+  );
+});

expect/_equal.ts

@@ -3,7 +3,7 @@
 // This file is copied from `std/assert`.
 
 import type { EqualOptions } from "./_types.ts";
-import { Any, Anything, ArrayContaining } from "./_asymmetric_matchers.ts";
+import { AsymmetricMatcher } from "./_asymmetric_matchers.ts";
 
 function isKeyedCollection(x: unknown): x is Set<unknown> {
   return [Symbol.iterator, "size"].every((k) => k in (x as Set<unknown>));
@@ -15,6 +15,23 @@ function constructorsEqual(a: object, b: object) {
     !a.constructor && b.constructor === Object;
 }
 
+function asymmetricEqual(a: unknown, b: unknown) {
+  const asymmetricA = a instanceof AsymmetricMatcher;
+  const asymmetricB = b instanceof AsymmetricMatcher;
+
+  if (asymmetricA && asymmetricB) {
+    return undefined;
+  }
+
+  if (asymmetricA) {
+    return a.equals(b);
+  }
+
+  if (asymmetricB) {
+    return b.equals(a);
+  }
+}
+
 /**
  * Deep equality comparison used in assertions
  * @param c actual value
@@ -48,15 +65,12 @@ 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);
+
+    const asymmetric = asymmetricEqual(a, b);
+    if (asymmetric !== undefined) {
+      return asymmetric;
     }
+
     if (a instanceof Date && b instanceof Date) {
       const aTime = a.getTime();
       const bTime = b.getTime();

expect/_string_containing_test.ts

@@ -0,0 +1,18 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+
+Deno.test("expect.stringContaining() with strings", () => {
+  expect("https://deno.com/").toEqual(expect.stringContaining("deno"));
+  expect("function").toEqual(expect.stringContaining("func"));
+
+  expect("Hello, World").not.toEqual(expect.stringContaining("hello"));
+  expect("foobar").not.toEqual(expect.stringContaining("bazz"));
+});
+
+Deno.test("expect.stringContaining() with other types", () => {
+  expect(123).not.toEqual(expect.stringContaining("1"));
+  expect(true).not.toEqual(expect.stringContaining("true"));
+  expect(["foo", "bar"]).not.toEqual(expect.stringContaining("foo"));
+  expect({ foo: "bar" }).not.toEqual(expect.stringContaining(`{ foo: "bar" }`));
+});

expect/_string_matching_test.ts

@@ -0,0 +1,19 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { expect } from "./expect.ts";
+
+Deno.test("expect.stringMatching() with strings", () => {
+  expect("deno_std").toEqual(expect.stringMatching("std"));
+  expect("function").toEqual(expect.stringMatching("func"));
+
+  expect("Hello, World").not.toEqual(expect.stringMatching("hello"));
+  expect("foobar").not.toEqual(expect.stringMatching("bazz"));
+});
+
+Deno.test("expect.stringMatching() with RegExp", () => {
+  expect("deno_std").toEqual(expect.stringMatching(/std/));
+  expect("0123456789").toEqual(expect.stringMatching(/\d+/));
+
+  expect("\e").not.toEqual(expect.stringMatching(/\s/));
+  expect("queue").not.toEqual(expect.stringMatching(/en/));
+});

expect/expect.ts

@@ -51,7 +51,14 @@ import {
   toThrow,
 } from "./_matchers.ts";
 import { isPromiseLike } from "./_utils.ts";
-import { any, anything, arrayContaining } from "./_asymmetric_matchers.ts";
+import {
+  any,
+  anything,
+  arrayContaining,
+  closeTo,
+  stringContaining,
+  stringMatching,
+} from "./_asymmetric_matchers.ts";
 
 const matchers: Record<MatcherKey, Matcher> = {
   lastCalledWith: toHaveBeenLastCalledWith,
@@ -191,6 +198,10 @@ export function expect(value: unknown, customMessage?: string): Expected {
 
 expect.addEqualityTesters = addCustomEqualityTesters;
 expect.extend = setExtendMatchers;
+
 expect.anything = anything;
 expect.any = any;
 expect.arrayContaining = arrayContaining;
+expect.closeTo = closeTo;
+expect.stringContaining = stringContaining;
+expect.stringMatching = stringMatching;

expect/mod.ts

@@ -3,9 +3,10 @@
 // This module is browser compatible.
 
 /**
- * This module provides jest compatible expect assertion functionality.
+ * This module provides Jest compatible expect assertion functionality.
  *
- * Currently this module supports the following matchers:
+ * Currently this module supports the following functions:
+ * - Common matchers:
  *   - `toBe`
  *   - `toEqual`
  *   - `toStrictEqual`
@@ -29,8 +30,7 @@
  *   - `toThrow`
  *   - `toHaveProperty`
  *   - `toHaveLength`
- *
- * Also this module supports the following mock related matchers:
+ * - Mock related matchers:
  *   - `toHaveBeenCalled`
  *   - `toHaveBeenCalledTimes`
  *   - `toHaveBeenCalledWith`
@@ -41,32 +41,33 @@
  *   - `toHaveReturnedWith`
  *   - `toHaveLastReturnedWith`
  *   - `toHaveNthReturnedWith`
- *
- * The following matchers are not supported yet:
- * - `toMatchSnapShot`
- * - `toMatchInlineSnapShot`
- * - `toThrowErrorMatchingSnapShot`
- * - `toThrowErrorMatchingInlineSnapShot`
- *
- * The following asymmetric matchers are not supported yet:
+ * - Asymmetric matchers:
  *   - `expect.anything`
  *   - `expect.any`
  *   - `expect.arrayContaining`
  *   - `expect.not.arrayContaining`
- * - `expect.closedTo`
- * - `expect.objectContaining`
- * - `expect.not.objectContaining`
+ *   - `expect.closeTo`
  *   - `expect.stringContaining`
  *   - `expect.not.stringContaining`
  *   - `expect.stringMatching`
  *   - `expect.not.stringMatching`
+ * - Utilities:
+ *   - `expect.addEqualityTester`
+ *   - `expect.extend`
  *
- * The following uitlities are not supported yet:
+ * Only these functions are still not available:
+ * - Matchers:
+ *   - `toMatchSnapShot`
+ *   - `toMatchInlineSnapShot`
+ *   - `toThrowErrorMatchingSnapShot`
+ *   - `toThrowErrorMatchingInlineSnapShot`
+ * - Asymmetric matchers:
+ *   - `expect.objectContaining`
+ *   - `expect.not.objectContaining`
+ * - Utilities:
  *   - `expect.assertions`
  *   - `expect.hasAssertions`
- * - `expect.addEqualityTester`
  *   - `expect.addSnapshotSerializer`
- * - `expect.extend`
  *
  * This module is largely inspired by {@link https://github.com/allain/expect | x/expect} module by Allain Lalonde.
  *