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std/testing/mock.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
/** A mocking and spying library. * * Test spies are function stand-ins that are used to assert if a function's * internal behavior matches expectations. Test spies on methods keep the original * behavior but allow you to test how the method is called and what it returns. * Test stubs are an extension of test spies that also replaces the original * methods behavior. * * ## Spying * * Say we have two functions, `square` and `multiply`, if we want to assert that * the `multiply` function is called during execution of the `square` function we * need a way to spy on the `multiply` function. There are a few ways to achieve * this with Spies, one is to have the `square` function take the `multiply` * multiply as a parameter. * * This way, we can call `square(multiply, value)` in the application code or wrap * a spy function around the `multiply` function and call * `square(multiplySpy, value)` in the testing code. * * ```ts * import { * assertSpyCall, * assertSpyCalls, * spy, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * function multiply(a: number, b: number): number { * return a * b; * } * * function square( * multiplyFn: (a: number, b: number) => number, * value: number, * ): number { * return multiplyFn(value, value); * } * * Deno.test("square calls multiply and returns results", () => { * const multiplySpy = spy(multiply); * * assertEquals(square(multiplySpy, 5), 25); * * // asserts that multiplySpy was called at least once and details about the first call. * assertSpyCall(multiplySpy, 0, { * args: [5, 5], * returned: 25, * }); * * // asserts that multiplySpy was only called once. * assertSpyCalls(multiplySpy, 1); * }); * ``` * * If you prefer not adding additional parameters for testing purposes only, you * can use spy to wrap a method on an object instead. In the following example, the * exported `_internals` object has the `multiply` function we want to call as a * method and the `square` function calls `_internals.multiply` instead of * `multiply`. * * This way, we can call `square(value)` in both the application code and testing * code. Then spy on the `multiply` method on the `_internals` object in the * testing code to be able to spy on how the `square` function calls the `multiply` * function. * * ```ts * import { * assertSpyCall, * assertSpyCalls, * spy, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * function multiply(a: number, b: number): number { * return a * b; * } * * function square(value: number): number { * return _internals.multiply(value, value); * } * * const _internals = { multiply }; * * Deno.test("square calls multiply and returns results", () => { * const multiplySpy = spy(_internals, "multiply"); * * try { * assertEquals(square(5), 25); * } finally { * // unwraps the multiply method on the _internals object * multiplySpy.restore(); * } * * // asserts that multiplySpy was called at least once and details about the first call. * assertSpyCall(multiplySpy, 0, { * args: [5, 5], * returned: 25, * }); * * // asserts that multiplySpy was only called once. * assertSpyCalls(multiplySpy, 1); * }); * ``` * * One difference you may have noticed between these two examples is that in the * second we call the `restore` method on `multiplySpy` function. That is needed to * remove the spy wrapper from the `_internals` object's `multiply` method. The * `restore` method is called in a finally block to ensure that it is restored * whether or not the assertion in the try block is successful. The `restore` * method didn't need to be called in the first example because the `multiply` * function was not modified in any way like the `_internals` object was in the * second example. * * Method spys are disposable, meaning that you can have them automatically restore * themselves with the `using` keyword. Using this approach is cleaner because you * do not need to wrap your assertions in a try statement to ensure you restore the * methods before the tests finish. * * ```ts * import { * assertSpyCall, * assertSpyCalls, * spy, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * function multiply(a: number, b: number): number { * return a * b; * } * * function square(value: number): number { * return _internals.multiply(value, value); * } * * const _internals = { multiply }; * * Deno.test("square calls multiply and returns results", () => { * using multiplySpy = spy(_internals, "multiply"); * * assertEquals(square(5), 25); * * // asserts that multiplySpy was called at least once and details about the first call. * assertSpyCall(multiplySpy, 0, { * args: [5, 5], * returned: 25, * }); * * // asserts that multiplySpy was only called once. * assertSpyCalls(multiplySpy, 1); * }); * ``` * * ## Stubbing * * Say we have two functions, `randomMultiple` and `randomInt`, if we want to * assert that `randomInt` is called during execution of `randomMultiple` we need a * way to spy on the `randomInt` function. That could be done with either of the * spying techniques previously mentioned. To be able to verify that the * `randomMultiple` function returns the value we expect it to for what `randomInt` * returns, the easiest way would be to replace the `randomInt` function's behavior * with more predictable behavior. * * You could use the first spying technique to do that but that would require * adding a `randomInt` parameter to the `randomMultiple` function. * * You could also use the second spying technique to do that, but your assertions * would not be as predictable due to the `randomInt` function returning random * values. * * Say we want to verify it returns correct values for both negative and positive * random integers. We could easily do that with stubbing. The below example is * similar to the second spying technique example but instead of passing the call * through to the original `randomInt` function, we are going to replace * `randomInt` with a function that returns pre-defined values. * * The mock module includes some helper functions to make creating common stubs * easy. The `returnsNext` function takes an array of values we want it to return * on consecutive calls. * * ```ts * import { * assertSpyCall, * assertSpyCalls, * returnsNext, * stub, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * function randomInt(lowerBound: number, upperBound: number): number { * return lowerBound + Math.floor(Math.random() * (upperBound - lowerBound)); * } * * function randomMultiple(value: number): number { * return value * _internals.randomInt(-10, 10); * } * * const _internals = { randomInt }; * * Deno.test("randomMultiple uses randomInt to generate random multiples between -10 and 10 times the value", () => { * const randomIntStub = stub(_internals, "randomInt", returnsNext([-3, 3])); * * try { * assertEquals(randomMultiple(5), -15); * assertEquals(randomMultiple(5), 15); * } finally { * // unwraps the randomInt method on the _internals object * randomIntStub.restore(); * } * * // asserts that randomIntStub was called at least once and details about the first call. * assertSpyCall(randomIntStub, 0, { * args: [-10, 10], * returned: -3, * }); * // asserts that randomIntStub was called at least twice and details about the second call. * assertSpyCall(randomIntStub, 1, { * args: [-10, 10], * returned: 3, * }); * * // asserts that randomIntStub was only called twice. * assertSpyCalls(randomIntStub, 2); * }); * ``` * * Like method spys, stubs are disposable, meaning that you can have them automatically * restore themselves with the `using` keyword. Using this approach is cleaner because * you do not need to wrap your assertions in a try statement to ensure you restore the * methods before the tests finish. * * ```ts * import { * assertSpyCall, * assertSpyCalls, * returnsNext, * stub, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * function randomInt(lowerBound: number, upperBound: number): number { * return lowerBound + Math.floor(Math.random() * (upperBound - lowerBound)); * } * * function randomMultiple(value: number): number { * return value * _internals.randomInt(-10, 10); * } * * const _internals = { randomInt }; * * Deno.test("randomMultiple uses randomInt to generate random multiples between -10 and 10 times the value", () => { * using randomIntStub = stub(_internals, "randomInt", returnsNext([-3, 3])); * * assertEquals(randomMultiple(5), -15); * assertEquals(randomMultiple(5), 15); * * // asserts that randomIntStub was called at least once and details about the first call. * assertSpyCall(randomIntStub, 0, { * args: [-10, 10], * returned: -3, * }); * // asserts that randomIntStub was called at least twice and details about the second call. * assertSpyCall(randomIntStub, 1, { * args: [-10, 10], * returned: 3, * }); * * // asserts that randomIntStub was only called twice. * assertSpyCalls(randomIntStub, 2); * }); * ``` * * ## Faking time * * Say we have a function that has time based behavior that we would like to test. * With real time, that could cause tests to take much longer than they should. If * you fake time, you could simulate how your function would behave over time * starting from any point in time. Below is an example where we want to test that * the callback is called every second. * * With `FakeTime` we can do that. When the `FakeTime` instance is created, it * splits from real time. The `Date`, `setTimeout`, `clearTimeout`, `setInterval` * and `clearInterval` globals are replaced with versions that use the fake time * until real time is restored. You can control how time ticks forward with the * `tick` method on the `FakeTime` instance. * * ```ts * import { * assertSpyCalls, * spy, * } from "https://deno.land/std@$STD_VERSION/testing/mock.ts"; * import { FakeTime } from "https://deno.land/std@$STD_VERSION/testing/time.ts"; * * function secondInterval(cb: () => void): number { * return setInterval(cb, 1000); * } * * Deno.test("secondInterval calls callback every second and stops after being cleared", () => { * using time = new FakeTime(); * * const cb = spy(); * const intervalId = secondInterval(cb); * assertSpyCalls(cb, 0); * time.tick(500); * assertSpyCalls(cb, 0); * time.tick(500); * assertSpyCalls(cb, 1); * time.tick(3500); * assertSpyCalls(cb, 4); * * clearInterval(intervalId); * time.tick(1000); * assertSpyCalls(cb, 4); * }); * ``` * * This module is browser compatible. * * @module */
import { assertEquals } from "../assert/assert_equals.ts";import { assertIsError } from "../assert/assert_is_error.ts";import { assertRejects } from "../assert/assert_rejects.ts";import { AssertionError } from "../assert/assertion_error.ts";
/** An error related to spying on a function or instance method. */export class MockError extends Error { constructor(message: string) { super(message); this.name = "MockError"; }}
/** Call information recorded by a spy. */export interface SpyCall< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> { /** Arguments passed to a function when called. */ args: Args; /** The value that was returned by a function. */ returned?: Return; /** The error value that was thrown by a function. */ error?: Error; /** The instance that a method was called on. */ self?: Self;}
/** A function or instance method wrapper that records all calls made to it. */export interface Spy< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> { (this: Self, ...args: Args): Return; /** The function that is being spied on. */ original: (this: Self, ...args: Args) => Return; /** Information about calls made to the function or instance method. */ calls: SpyCall<Self, Args, Return>[]; /** Whether or not the original instance method has been restored. */ restored: boolean; /** If spying on an instance method, this restores the original instance method. */ restore(): void;}
/** An instance method wrapper that records all calls made to it. */export interface MethodSpy< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> extends Spy<Self, Args, Return>, Disposable {}
/** Wraps a function with a Spy. */function functionSpy< Self, Args extends unknown[], Return,>(func?: (this: Self, ...args: Args) => Return): Spy<Self, Args, Return> { const original = func ?? (() => {}) as (this: Self, ...args: Args) => Return; const calls: SpyCall<Self, Args, Return>[] = []; const spy = function (this: Self, ...args: Args): Return { const call: SpyCall<Self, Args, Return> = { args }; if (this) call.self = this; try { call.returned = original.apply(this, args); } catch (error) { call.error = error as Error; calls.push(call); throw error; } calls.push(call); return call.returned; } as Spy<Self, Args, Return>; Object.defineProperties(spy, { original: { enumerable: true, value: original, }, calls: { enumerable: true, value: calls, }, restored: { enumerable: true, get: () => false, }, restore: { enumerable: true, value: () => { throw new MockError("function cannot be restored"); }, }, }); return spy;}
/** Checks if a function is a spy. */function isSpy<Self, Args extends unknown[], Return>( func: ((this: Self, ...args: Args) => Return) | unknown,): func is Spy<Self, Args, Return> { const spy = func as Spy<Self, Args, Return>; return typeof spy === "function" && typeof spy.original === "function" && typeof spy.restored === "boolean" && typeof spy.restore === "function" && Array.isArray(spy.calls);}
// deno-lint-ignore no-explicit-anyconst sessions: Set<Spy<any, any[], any>>[] = [];// deno-lint-ignore no-explicit-anyfunction getSession(): Set<Spy<any, any[], any>> { if (sessions.length === 0) sessions.push(new Set()); return sessions.at(-1)!;}// deno-lint-ignore no-explicit-anyfunction registerMock(spy: Spy<any, any[], any>) { const session = getSession(); session.add(spy);}// deno-lint-ignore no-explicit-anyfunction unregisterMock(spy: Spy<any, any[], any>) { const session = getSession(); session.delete(spy);}
/** * Creates a session that tracks all mocks created before it's restored. * If a callback is provided, it restores all mocks created within it. */export function mockSession(): number;export function mockSession< Self, Args extends unknown[], Return,>( func: (this: Self, ...args: Args) => Return,): (this: Self, ...args: Args) => Return;export function mockSession< Self, Args extends unknown[], Return,>( func?: (this: Self, ...args: Args) => Return,): number | ((this: Self, ...args: Args) => Return) { if (func) { return function (this: Self, ...args: Args): Return { const id = sessions.length; sessions.push(new Set()); try { return func.apply(this, args); } finally { restore(id); } }; } else { sessions.push(new Set()); return sessions.length - 1; }}
/** Creates an async session that tracks all mocks created before the promise resolves. */export function mockSessionAsync< Self, Args extends unknown[], Return,>( func: (this: Self, ...args: Args) => Promise<Return>,): (this: Self, ...args: Args) => Promise<Return> { return async function (this: Self, ...args: Args): Promise<Return> { const id = sessions.length; sessions.push(new Set()); try { return await func.apply(this, args); } finally { restore(id); } };}
/** * Restores all mocks registered in the current session that have not already been restored. * If an id is provided, it will restore all mocks registered in the session associed with that id that have not already been restored. */export function restore(id?: number) { id ??= (sessions.length || 1) - 1; while (id < sessions.length) { const session = sessions.pop(); if (session) { for (const value of session) { value.restore(); } } }}
/** Wraps an instance method with a Spy. */function methodSpy< Self, Args extends unknown[], Return,>(self: Self, property: keyof Self): MethodSpy<Self, Args, Return> { if (typeof self[property] !== "function") { throw new MockError("property is not an instance method"); } if (isSpy(self[property])) { throw new MockError("already spying on instance method"); }
const propertyDescriptor = Object.getOwnPropertyDescriptor(self, property); if (propertyDescriptor && !propertyDescriptor.configurable) { throw new MockError("cannot spy on non configurable instance method"); }
const original = self[property] as unknown as ( this: Self, ...args: Args ) => Return, calls: SpyCall<Self, Args, Return>[] = []; let restored = false; const spy = function (this: Self, ...args: Args): Return { const call: SpyCall<Self, Args, Return> = { args }; if (this) call.self = this; try { call.returned = original.apply(this, args); } catch (error) { call.error = error as Error; calls.push(call); throw error; } calls.push(call); return call.returned; } as MethodSpy<Self, Args, Return>; Object.defineProperties(spy, { original: { enumerable: true, value: original, }, calls: { enumerable: true, value: calls, }, restored: { enumerable: true, get: () => restored, }, restore: { enumerable: true, value: () => { if (restored) { throw new MockError("instance method already restored"); } if (propertyDescriptor) { Object.defineProperty(self, property, propertyDescriptor); } else { delete self[property]; } restored = true; unregisterMock(spy); }, }, [Symbol.dispose]: { value: () => { spy.restore(); }, }, });
Object.defineProperty(self, property, { configurable: true, enumerable: propertyDescriptor?.enumerable, writable: propertyDescriptor?.writable, value: spy, });
registerMock(spy); return spy;}
/** A constructor wrapper that records all calls made to it. */export interface ConstructorSpy< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[],> { new (...args: Args): Self; /** The function that is being spied on. */ original: new (...args: Args) => Self; /** Information about calls made to the function or instance method. */ calls: SpyCall<Self, Args, Self>[]; /** Whether or not the original instance method has been restored. */ restored: boolean; /** If spying on an instance method, this restores the original instance method. */ restore(): void;}
/** Wraps a constructor with a Spy. */function constructorSpy< Self, Args extends unknown[],>( constructor: new (...args: Args) => Self,): ConstructorSpy<Self, Args> { const original = constructor; const calls: SpyCall<Self, Args, Self>[] = []; // @ts-ignore TS2509: Can't know the type of `original` statically. const spy = class extends original { constructor(...args: Args) { super(...args); const call: SpyCall<Self, Args, Self> = { args }; try { call.returned = this as unknown as Self; } catch (error) { call.error = error as Error; calls.push(call); throw error; } calls.push(call); } static readonly name = original.name; static readonly original = original; static readonly calls = calls; static readonly restored = false; static restore() { throw new MockError("constructor cannot be restored"); } } as ConstructorSpy<Self, Args>; return spy;}
/** Utility for extracting the arguments type from a property */type GetParametersFromProp< Self, Prop extends keyof Self,> = Self[Prop] extends (...args: infer Args) => unknown ? Args : unknown[];
/** Utility for extracting the return type from a property */type GetReturnFromProp< Self, Prop extends keyof Self,> // deno-lint-ignore no-explicit-any = Self[Prop] extends (...args: any[]) => infer Return ? Return : unknown;
type SpyLike< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> = Spy<Self, Args, Return> | ConstructorSpy<Self, Args>;
/** Wraps a function or instance method with a Spy. */export function spy< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], Return = undefined,>(): Spy<Self, Args, Return>;export function spy< Self, Args extends unknown[], Return,>(func: (this: Self, ...args: Args) => Return): Spy<Self, Args, Return>;export function spy< Self, Args extends unknown[], Return = undefined,>( constructor: new (...args: Args) => Self,): ConstructorSpy<Self, Args>;export function spy< Self, Prop extends keyof Self,>( self: Self, property: Prop,): MethodSpy< Self, GetParametersFromProp<Self, Prop>, GetReturnFromProp<Self, Prop>>;export function spy< Self, Args extends unknown[], Return,>( funcOrConstOrSelf?: | ((this: Self, ...args: Args) => Return) | (new (...args: Args) => Self) | Self, property?: keyof Self,): SpyLike<Self, Args, Return> { if (!funcOrConstOrSelf) { return functionSpy<Self, Args, Return>(); } else if (property !== undefined) { return methodSpy<Self, Args, Return>(funcOrConstOrSelf as Self, property); } else if (funcOrConstOrSelf.toString().startsWith("class")) { return constructorSpy<Self, Args>( funcOrConstOrSelf as new (...args: Args) => Self, ); } else { return functionSpy<Self, Args, Return>( funcOrConstOrSelf as (this: Self, ...args: Args) => Return, ); }}
/** An instance method replacement that records all calls made to it. */export interface Stub< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> extends MethodSpy<Self, Args, Return> { /** The function that is used instead of the original. */ fake: (this: Self, ...args: Args) => Return;}
/** Replaces an instance method with a Stub. */export function stub< Self, Prop extends keyof Self,>( self: Self, property: Prop,): Stub<Self, GetParametersFromProp<Self, Prop>, GetReturnFromProp<Self, Prop>>;export function stub< Self, Prop extends keyof Self,>( self: Self, property: Prop, func: ( this: Self, ...args: GetParametersFromProp<Self, Prop> ) => GetReturnFromProp<Self, Prop>,): Stub<Self, GetParametersFromProp<Self, Prop>, GetReturnFromProp<Self, Prop>>;export function stub< Self, Args extends unknown[], Return,>( self: Self, property: keyof Self, func?: (this: Self, ...args: Args) => Return,): Stub<Self, Args, Return> { if (self[property] !== undefined && typeof self[property] !== "function") { throw new MockError("property is not an instance method"); } if (isSpy(self[property])) { throw new MockError("already spying on instance method"); }
const propertyDescriptor = Object.getOwnPropertyDescriptor(self, property); if (propertyDescriptor && !propertyDescriptor.configurable) { throw new MockError("cannot spy on non configurable instance method"); }
const fake = func ?? (() => {}) as (this: Self, ...args: Args) => Return;
const original = self[property] as unknown as ( this: Self, ...args: Args ) => Return, calls: SpyCall<Self, Args, Return>[] = []; let restored = false; const stub = function (this: Self, ...args: Args): Return { const call: SpyCall<Self, Args, Return> = { args }; if (this) call.self = this; try { call.returned = fake.apply(this, args); } catch (error) { call.error = error as Error; calls.push(call); throw error; } calls.push(call); return call.returned; } as Stub<Self, Args, Return>; Object.defineProperties(stub, { original: { enumerable: true, value: original, }, fake: { enumerable: true, value: fake, }, calls: { enumerable: true, value: calls, }, restored: { enumerable: true, get: () => restored, }, restore: { enumerable: true, value: () => { if (restored) { throw new MockError("instance method already restored"); } if (propertyDescriptor) { Object.defineProperty(self, property, propertyDescriptor); } else { delete self[property]; } restored = true; unregisterMock(stub); }, }, [Symbol.dispose]: { value: () => { stub.restore(); }, }, });
Object.defineProperty(self, property, { configurable: true, enumerable: propertyDescriptor?.enumerable, writable: propertyDescriptor?.writable, value: stub, });
registerMock(stub); return stub;}
/** * Asserts that a spy is called as much as expected and no more. */export function assertSpyCalls< Self, Args extends unknown[], Return,>( spy: SpyLike<Self, Args, Return>, expectedCalls: number,) { try { assertEquals(spy.calls.length, expectedCalls); } catch (e) { assertIsError(e); let message = spy.calls.length < expectedCalls ? "spy not called as much as expected:\n" : "spy called more than expected:\n"; message += e.message.split("\n").slice(1).join("\n"); throw new AssertionError(message); }}
/** Call information recorded by a spy. */export interface ExpectedSpyCall< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[], // deno-lint-ignore no-explicit-any Return = any,> { /** Arguments passed to a function when called. */ args?: [...Args, ...unknown[]]; /** The instance that a method was called on. */ self?: Self; /** * The value that was returned by a function. * If you expect a promise to reject, expect error instead. */ returned?: Return; error?: { /** The class for the error that was thrown by a function. */ // deno-lint-ignore no-explicit-any Class?: new (...args: any[]) => Error; /** Part of the message for the error that was thrown by a function. */ msgIncludes?: string; };}
function getSpyCall< Self, Args extends unknown[], Return,>( spy: SpyLike<Self, Args, Return>, callIndex: number,): SpyCall { if (spy.calls.length < (callIndex + 1)) { throw new AssertionError("spy not called as much as expected"); } return spy.calls[callIndex]!;}/** * Asserts that a spy is called as expected. */export function assertSpyCall< Self, Args extends unknown[], Return,>( spy: SpyLike<Self, Args, Return>, callIndex: number, expected?: ExpectedSpyCall<Self, Args, Return>,) { const call = getSpyCall(spy, callIndex); if (expected) { if (expected.args) { try { assertEquals(call.args, expected.args); } catch (e) { assertIsError(e); throw new AssertionError( "spy not called with expected args:\n" + e.message.split("\n").slice(1).join("\n"), ); } }
if ("self" in expected) { try { assertEquals(call.self, expected.self); } catch (e) { assertIsError(e); let message = expected.self ? "spy not called as method on expected self:\n" : "spy not expected to be called as method on object:\n"; message += e.message.split("\n").slice(1).join("\n"); throw new AssertionError(message); } }
if ("returned" in expected) { if ("error" in expected) { throw new TypeError( "do not expect error and return, only one should be expected", ); } if (call.error) { throw new AssertionError( "spy call did not return expected value, an error was thrown.", ); } try { assertEquals(call.returned, expected.returned); } catch (e) { assertIsError(e); throw new AssertionError( "spy call did not return expected value:\n" + e.message.split("\n").slice(1).join("\n"), ); } }
if ("error" in expected) { if ("returned" in call) { throw new AssertionError( "spy call did not throw an error, a value was returned.", ); } assertIsError( call.error, expected.error?.Class, expected.error?.msgIncludes, ); } }}
/** * Asserts that an async spy is called as expected. */export async function assertSpyCallAsync< Self, Args extends unknown[], Return,>( spy: SpyLike<Self, Args, Promise<Return>>, callIndex: number, expected?: ExpectedSpyCall<Self, Args, Promise<Return> | Return>,) { const expectedSync = expected && { ...expected }; if (expectedSync) { delete expectedSync.returned; delete expectedSync.error; } assertSpyCall(spy, callIndex, expectedSync); const call = getSpyCall(spy, callIndex);
if (call.error) { throw new AssertionError( "spy call did not return a promise, an error was thrown.", ); } if (call.returned !== Promise.resolve(call.returned)) { throw new AssertionError( "spy call did not return a promise, a value was returned.", ); }
if (expected) { if ("returned" in expected) { if ("error" in expected) { throw new TypeError( "do not expect error and return, only one should be expected", ); } if (call.error) { throw new AssertionError( "spy call did not return expected value, an error was thrown.", ); } let expectedResolved; try { expectedResolved = await expected.returned; } catch { throw new TypeError( "do not expect rejected promise, expect error instead", ); }
let resolved; try { resolved = await call.returned; } catch { throw new AssertionError("spy call returned promise was rejected"); }
try { assertEquals(resolved, expectedResolved); } catch (e) { assertIsError(e); throw new AssertionError( "spy call did not resolve to expected value:\n" + e.message.split("\n").slice(1).join("\n"), ); } }
if ("error" in expected) { await assertRejects( () => Promise.resolve(call.returned), expected.error?.Class ?? Error, expected.error?.msgIncludes ?? "", ); } }}
/** * Asserts that a spy is called with a specific arg as expected. */export function assertSpyCallArg< Self, Args extends unknown[], Return, ExpectedArg,>( spy: SpyLike<Self, Args, Return>, callIndex: number, argIndex: number, expected: ExpectedArg,): ExpectedArg { const call = getSpyCall(spy, callIndex); const arg = call?.args[argIndex]; assertEquals(arg, expected); return arg as ExpectedArg;}
/** * Asserts that an spy is called with a specific range of args as expected. * If a start and end index is not provided, the expected will be compared against all args. * If a start is provided without an end index, the expected will be compared against all args from the start index to the end. * The end index is not included in the range of args that are compared. */export function assertSpyCallArgs< Self, Args extends unknown[], Return, ExpectedArgs extends unknown[],>( spy: SpyLike<Self, Args, Return>, callIndex: number, expected: ExpectedArgs,): ExpectedArgs;export function assertSpyCallArgs< Self, Args extends unknown[], Return, ExpectedArgs extends unknown[],>( spy: SpyLike<Self, Args, Return>, callIndex: number, argsStart: number, expected: ExpectedArgs,): ExpectedArgs;export function assertSpyCallArgs< Self, Args extends unknown[], Return, ExpectedArgs extends unknown[],>( spy: SpyLike<Self, Args, Return>, callIndex: number, argStart: number, argEnd: number, expected: ExpectedArgs,): ExpectedArgs;export function assertSpyCallArgs< ExpectedArgs extends unknown[], Args extends unknown[], Return, Self,>( spy: SpyLike<Self, Args, Return>, callIndex: number, argsStart?: number | ExpectedArgs, argsEnd?: number | ExpectedArgs, expected?: ExpectedArgs,): ExpectedArgs { const call = getSpyCall(spy, callIndex); if (!expected) { expected = argsEnd as ExpectedArgs; argsEnd = undefined; } if (!expected) { expected = argsStart as ExpectedArgs; argsStart = undefined; } const args = typeof argsEnd === "number" ? call.args.slice(argsStart as number, argsEnd) : typeof argsStart === "number" ? call.args.slice(argsStart) : call.args; assertEquals(args, expected); return args as ExpectedArgs;}
/** Creates a function that returns the instance the method was called on. */export function returnsThis< // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[],>(): (this: Self, ...args: Args) => Self { return function (this: Self): Self { return this; };}
/** Creates a function that returns one of its arguments. */// deno-lint-ignore no-explicit-anyexport function returnsArg<Arg, Self = any>( idx: number,): (this: Self, ...args: Arg[]) => Arg | undefined { return function (...args: Arg[]): Arg | undefined { return args[idx]; };}
/** Creates a function that returns its arguments or a subset of them. If end is specified, it will return arguments up to but not including the end. */export function returnsArgs< Args extends unknown[], // deno-lint-ignore no-explicit-any Self = any,>( start = 0, end?: number,): (this: Self, ...args: Args) => Args { return function (this: Self, ...args: Args): Args { return args.slice(start, end) as Args; };}
/** Creates a function that returns the iterable values. Any iterable values that are errors will be thrown. */export function returnsNext< Return, // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[],>( values: Iterable<Return | Error>,): (this: Self, ...args: Args) => Return { const gen = (function* returnsValue() { yield* values; })(); let calls = 0; return function () { const next = gen.next(); if (next.done) { throw new MockError(`not expected to be called more than ${calls} times`); } calls++; const { value } = next; if (value instanceof Error) throw value; return value; };}
/** Creates a function that resolves the awaited iterable values. Any awaited iterable values that are errors will be thrown. */export function resolvesNext< Return, // deno-lint-ignore no-explicit-any Self = any, // deno-lint-ignore no-explicit-any Args extends unknown[] = any[],>( iterable: | Iterable<Return | Error | Promise<Return | Error>> | AsyncIterable<Return | Error | Promise<Return | Error>>,): (this: Self, ...args: Args) => Promise<Return> { const gen = (async function* returnsValue() { yield* iterable; })(); let calls = 0; return async function () { const next = await gen.next(); if (next.done) { throw new MockError(`not expected to be called more than ${calls} times`); } calls++; const { value } = next; if (value instanceof Error) throw value; return value; };}