std/testing/asserts.ts

807 lines
23 KiB
TypeScript

// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
/** A library of assertion functions.
*
* This module is browser compatible, but do not rely on good formatting of
* values for AssertionError messages in browsers.
*
* @module
*/
import { red, stripColor } from "../fmt/colors.ts";
import { buildMessage, diff, diffstr } from "./_diff.ts";
import { format } from "./_format.ts";
const CAN_NOT_DISPLAY = "[Cannot display]";
export class AssertionError extends Error {
override name = "AssertionError";
constructor(message: string) {
super(message);
}
}
function isKeyedCollection(x: unknown): x is Set<unknown> {
return [Symbol.iterator, "size"].every((k) => k in (x as Set<unknown>));
}
/**
* Deep equality comparison used in assertions
* @param c actual value
* @param d expected value
*/
export function equal(c: unknown, d: unknown): boolean {
const seen = new Map();
return (function compare(a: unknown, b: unknown): boolean {
// Have to render RegExp & Date for string comparison
// unless it's mistreated as object
if (
a &&
b &&
((a instanceof RegExp && b instanceof RegExp) ||
(a instanceof URL && b instanceof URL))
) {
return String(a) === String(b);
}
if (a instanceof Date && b instanceof Date) {
const aTime = a.getTime();
const bTime = b.getTime();
// Check for NaN equality manually since NaN is not
// equal to itself.
if (Number.isNaN(aTime) && Number.isNaN(bTime)) {
return true;
}
return aTime === bTime;
}
if (typeof a === "number" && typeof b === "number") {
return Number.isNaN(a) && Number.isNaN(b) || a === b;
}
if (Object.is(a, b)) {
return true;
}
if (a && typeof a === "object" && b && typeof b === "object") {
if (a && b && !constructorsEqual(a, b)) {
return false;
}
if (a instanceof WeakMap || b instanceof WeakMap) {
if (!(a instanceof WeakMap && b instanceof WeakMap)) return false;
throw new TypeError("cannot compare WeakMap instances");
}
if (a instanceof WeakSet || b instanceof WeakSet) {
if (!(a instanceof WeakSet && b instanceof WeakSet)) return false;
throw new TypeError("cannot compare WeakSet instances");
}
if (seen.get(a) === b) {
return true;
}
if (Object.keys(a || {}).length !== Object.keys(b || {}).length) {
return false;
}
seen.set(a, b);
if (isKeyedCollection(a) && isKeyedCollection(b)) {
if (a.size !== b.size) {
return false;
}
let unmatchedEntries = a.size;
for (const [aKey, aValue] of a.entries()) {
for (const [bKey, bValue] of b.entries()) {
/* Given that Map keys can be references, we need
* to ensure that they are also deeply equal */
if (
(aKey === aValue && bKey === bValue && compare(aKey, bKey)) ||
(compare(aKey, bKey) && compare(aValue, bValue))
) {
unmatchedEntries--;
break;
}
}
}
return unmatchedEntries === 0;
}
const merged = { ...a, ...b };
for (
const key of [
...Object.getOwnPropertyNames(merged),
...Object.getOwnPropertySymbols(merged),
]
) {
type Key = keyof typeof merged;
if (!compare(a && a[key as Key], b && b[key as Key])) {
return false;
}
if (((key in a) && (!(key in b))) || ((key in b) && (!(key in a)))) {
return false;
}
}
if (a instanceof WeakRef || b instanceof WeakRef) {
if (!(a instanceof WeakRef && b instanceof WeakRef)) return false;
return compare(a.deref(), b.deref());
}
return true;
}
return false;
})(c, d);
}
// deno-lint-ignore ban-types
function constructorsEqual(a: object, b: object) {
return a.constructor === b.constructor ||
a.constructor === Object && !b.constructor ||
!a.constructor && b.constructor === Object;
}
/** Make an assertion, error will be thrown if `expr` does not have truthy value. */
export function assert(expr: unknown, msg = ""): asserts expr {
if (!expr) {
throw new AssertionError(msg);
}
}
/** Make an assertion, error will be thrown if `expr` have truthy value. */
export function assertFalse(expr: unknown, msg = ""): asserts expr is false {
if (expr) {
throw new AssertionError(msg);
}
}
/**
* Make an assertion that `actual` and `expected` are equal, deeply. If not
* deeply equal, then throw.
*
* Type parameter can be specified to ensure values under comparison have the same type.
* For example:
* ```ts
* import { assertEquals } from "./asserts.ts";
*
* assertEquals<number>(1, 2)
* ```
*/
export function assertEquals<T>(actual: T, expected: T, msg?: string): void {
if (equal(actual, expected)) {
return;
}
let message = "";
const actualString = format(actual);
const expectedString = format(expected);
try {
const stringDiff = (typeof actual === "string") &&
(typeof expected === "string");
const diffResult = stringDiff
? diffstr(actual as string, expected as string)
: diff(actualString.split("\n"), expectedString.split("\n"));
const diffMsg = buildMessage(diffResult, { stringDiff }).join("\n");
message = `Values are not equal:\n${diffMsg}`;
} catch {
message = `\n${red(CAN_NOT_DISPLAY)} + \n\n`;
}
if (msg) {
message = msg;
}
throw new AssertionError(message);
}
/**
* Make an assertion that `actual` and `expected` are not equal, deeply.
* If not then throw.
*
* Type parameter can be specified to ensure values under comparison have the same type.
* For example:
* ```ts
* import { assertNotEquals } from "./asserts.ts";
*
* assertNotEquals<number>(1, 2)
* ```
*/
export function assertNotEquals<T>(actual: T, expected: T, msg?: string): void {
if (!equal(actual, expected)) {
return;
}
let actualString: string;
let expectedString: string;
try {
actualString = String(actual);
} catch {
actualString = "[Cannot display]";
}
try {
expectedString = String(expected);
} catch {
expectedString = "[Cannot display]";
}
if (!msg) {
msg = `actual: ${actualString} expected not to be: ${expectedString}`;
}
throw new AssertionError(msg);
}
/**
* Make an assertion that `actual` and `expected` are strictly equal. If
* not then throw.
*
* ```ts
* import { assertStrictEquals } from "./asserts.ts";
*
* assertStrictEquals(1, 2)
* ```
*/
export function assertStrictEquals<T>(
actual: unknown,
expected: T,
msg?: string,
): asserts actual is T {
if (Object.is(actual, expected)) {
return;
}
let message: string;
if (msg) {
message = msg;
} else {
const actualString = format(actual);
const expectedString = format(expected);
if (actualString === expectedString) {
const withOffset = actualString
.split("\n")
.map((l) => ` ${l}`)
.join("\n");
message =
`Values have the same structure but are not reference-equal:\n\n${
red(withOffset)
}\n`;
} else {
try {
const stringDiff = (typeof actual === "string") &&
(typeof expected === "string");
const diffResult = stringDiff
? diffstr(actual as string, expected as string)
: diff(actualString.split("\n"), expectedString.split("\n"));
const diffMsg = buildMessage(diffResult, { stringDiff }).join("\n");
message = `Values are not strictly equal:\n${diffMsg}`;
} catch {
message = `\n${red(CAN_NOT_DISPLAY)} + \n\n`;
}
}
}
throw new AssertionError(message);
}
/**
* Make an assertion that `actual` and `expected` are not strictly equal.
* If the values are strictly equal then throw.
*
* ```ts
* import { assertNotStrictEquals } from "./asserts.ts";
*
* assertNotStrictEquals(1, 1)
* ```
*/
export function assertNotStrictEquals<T>(
actual: T,
expected: T,
msg?: string,
): void {
if (!Object.is(actual, expected)) {
return;
}
throw new AssertionError(
msg ?? `Expected "actual" to be strictly unequal to: ${format(actual)}\n`,
);
}
/**
* Make an assertion that `actual` and `expected` are almost equal numbers through
* a given tolerance. It can be used to take into account IEEE-754 double-precision
* floating-point representation limitations.
* If the values are not almost equal then throw.
*
* ```ts
* import { assertAlmostEquals, assertThrows } from "./asserts.ts";
*
* assertAlmostEquals(0.1, 0.2);
*
* // Using a custom tolerance value
* assertAlmostEquals(0.1 + 0.2, 0.3, 1e-16);
* assertThrows(() => assertAlmostEquals(0.1 + 0.2, 0.3, 1e-17));
* ```
*/
export function assertAlmostEquals(
actual: number,
expected: number,
tolerance = 1e-7,
msg?: string,
) {
if (Object.is(actual, expected)) {
return;
}
const delta = Math.abs(expected - actual);
if (delta <= tolerance) {
return;
}
const f = (n: number) => Number.isInteger(n) ? n : n.toExponential();
throw new AssertionError(
msg ??
`actual: "${f(actual)}" expected to be close to "${f(expected)}": \
delta "${f(delta)}" is greater than "${f(tolerance)}"`,
);
}
// deno-lint-ignore no-explicit-any
type AnyConstructor = new (...args: any[]) => any;
type GetConstructorType<T extends AnyConstructor> = T extends // deno-lint-ignore no-explicit-any
new (...args: any) => infer C ? C
: never;
/**
* Make an assertion that `obj` is an instance of `type`.
* If not then throw.
*/
export function assertInstanceOf<T extends AnyConstructor>(
actual: unknown,
expectedType: T,
msg = "",
): asserts actual is GetConstructorType<T> {
if (!msg) {
const expectedTypeStr = expectedType.name;
let actualTypeStr = "";
if (actual === null) {
actualTypeStr = "null";
} else if (actual === undefined) {
actualTypeStr = "undefined";
} else if (typeof actual === "object") {
actualTypeStr = actual.constructor?.name ?? "Object";
} else {
actualTypeStr = typeof actual;
}
if (expectedTypeStr == actualTypeStr) {
msg = `Expected object to be an instance of "${expectedTypeStr}".`;
} else if (actualTypeStr == "function") {
msg =
`Expected object to be an instance of "${expectedTypeStr}" but was not an instanced object.`;
} else {
msg =
`Expected object to be an instance of "${expectedTypeStr}" but was "${actualTypeStr}".`;
}
}
assert(actual instanceof expectedType, msg);
}
/**
* Make an assertion that `obj` is not an instance of `type`.
* If so, then throw.
*/
export function assertNotInstanceOf<T extends AnyConstructor>(
actual: unknown,
unexpectedType: T,
msg = `Expected object to not be an instance of "${typeof unexpectedType}"`,
) {
assertFalse(actual instanceof unexpectedType, msg);
}
/**
* Make an assertion that actual is not null or undefined.
* If not then throw.
*/
export function assertExists<T>(
actual: T,
msg?: string,
): asserts actual is NonNullable<T> {
if (actual === undefined || actual === null) {
if (!msg) {
msg = `actual: "${actual}" expected to not be null or undefined`;
}
throw new AssertionError(msg);
}
}
/**
* Make an assertion that actual includes expected. If not
* then throw.
*/
export function assertStringIncludes(
actual: string,
expected: string,
msg?: string,
): void {
if (!actual.includes(expected)) {
if (!msg) {
msg = `actual: "${actual}" expected to contain: "${expected}"`;
}
throw new AssertionError(msg);
}
}
/**
* Make an assertion that `actual` includes the `expected` values.
* If not then an error will be thrown.
*
* Type parameter can be specified to ensure values under comparison have the same type.
* For example:
*
* ```ts
* import { assertArrayIncludes } from "./asserts.ts";
*
* assertArrayIncludes<number>([1, 2], [2])
* ```
*/
export function assertArrayIncludes<T>(
actual: ArrayLike<T>,
expected: ArrayLike<T>,
msg?: string,
): void {
const missing: unknown[] = [];
for (let i = 0; i < expected.length; i++) {
let found = false;
for (let j = 0; j < actual.length; j++) {
if (equal(expected[i], actual[j])) {
found = true;
break;
}
}
if (!found) {
missing.push(expected[i]);
}
}
if (missing.length === 0) {
return;
}
if (!msg) {
msg = `actual: "${format(actual)}" expected to include: "${
format(expected)
}"\nmissing: ${format(missing)}`;
}
throw new AssertionError(msg);
}
/**
* Make an assertion that `actual` match RegExp `expected`. If not
* then throw.
*/
export function assertMatch(
actual: string,
expected: RegExp,
msg?: string,
): void {
if (!expected.test(actual)) {
if (!msg) {
msg = `actual: "${actual}" expected to match: "${expected}"`;
}
throw new AssertionError(msg);
}
}
/**
* Make an assertion that `actual` not match RegExp `expected`. If match
* then throw.
*/
export function assertNotMatch(
actual: string,
expected: RegExp,
msg?: string,
): void {
if (expected.test(actual)) {
if (!msg) {
msg = `actual: "${actual}" expected to not match: "${expected}"`;
}
throw new AssertionError(msg);
}
}
/**
* Make an assertion that `actual` object is a subset of `expected` object, deeply.
* If not, then throw.
*/
export function assertObjectMatch(
// deno-lint-ignore no-explicit-any
actual: Record<PropertyKey, any>,
expected: Record<PropertyKey, unknown>,
): void {
type loose = Record<PropertyKey, unknown>;
function filter(a: loose, b: loose) {
const seen = new WeakMap();
return fn(a, b);
function fn(a: loose, b: loose): loose {
// Prevent infinite loop with circular references with same filter
if ((seen.has(a)) && (seen.get(a) === b)) {
return a;
}
seen.set(a, b);
// Filter keys and symbols which are present in both actual and expected
const filtered = {} as loose;
const entries = [
...Object.getOwnPropertyNames(a),
...Object.getOwnPropertySymbols(a),
]
.filter((key) => key in b)
.map((key) => [key, a[key as string]]) as Array<[string, unknown]>;
for (const [key, value] of entries) {
// On array references, build a filtered array and filter nested objects inside
if (Array.isArray(value)) {
const subset = (b as loose)[key];
if (Array.isArray(subset)) {
filtered[key] = fn({ ...value }, { ...subset });
continue;
}
} // On regexp references, keep value as it to avoid loosing pattern and flags
else if (value instanceof RegExp) {
filtered[key] = value;
continue;
} // On nested objects references, build a filtered object recursively
else if (typeof value === "object") {
const subset = (b as loose)[key];
if ((typeof subset === "object") && (subset)) {
// When both operands are maps, build a filtered map with common keys and filter nested objects inside
if ((value instanceof Map) && (subset instanceof Map)) {
filtered[key] = new Map(
[...value].filter(([k]) => subset.has(k)).map((
[k, v],
) => [k, typeof v === "object" ? fn(v, subset.get(k)) : v]),
);
continue;
}
// When both operands are set, build a filtered set with common values
if ((value instanceof Set) && (subset instanceof Set)) {
filtered[key] = new Set([...value].filter((v) => subset.has(v)));
continue;
}
filtered[key] = fn(value as loose, subset as loose);
continue;
}
}
filtered[key] = value;
}
return filtered;
}
}
return assertEquals(
// get the intersection of "actual" and "expected"
// side effect: all the instances' constructor field is "Object" now.
filter(actual, expected),
// set (nested) instances' constructor field to be "Object" without changing expected value.
// see https://github.com/denoland/deno_std/pull/1419
filter(expected, expected),
);
}
/**
* Forcefully throws a failed assertion
*/
export function fail(msg?: string): never {
assert(false, `Failed assertion${msg ? `: ${msg}` : "."}`);
}
/**
* Make an assertion that `error` is an `Error`.
* If not then an error will be thrown.
* An error class and a string that should be included in the
* error message can also be asserted.
*/
export function assertIsError<E extends Error = Error>(
error: unknown,
// deno-lint-ignore no-explicit-any
ErrorClass?: new (...args: any[]) => E,
msgIncludes?: string,
msg?: string,
): asserts error is E {
if (error instanceof Error === false) {
throw new AssertionError(`Expected "error" to be an Error object.`);
}
if (ErrorClass && !(error instanceof ErrorClass)) {
msg = `Expected error to be instance of "${ErrorClass.name}", but was "${
typeof error === "object" ? error?.constructor?.name : "[not an object]"
}"${msg ? `: ${msg}` : "."}`;
throw new AssertionError(msg);
}
if (
msgIncludes && (!(error instanceof Error) ||
!stripColor(error.message).includes(stripColor(msgIncludes)))
) {
msg = `Expected error message to include "${msgIncludes}", but got "${
error instanceof Error ? error.message : "[not an Error]"
}"${msg ? `: ${msg}` : "."}`;
throw new AssertionError(msg);
}
}
/** Executes a function, expecting it to throw. If it does not, then it
* throws. */
export function assertThrows(
fn: () => unknown,
msg?: string,
): unknown;
/** Executes a function, expecting it to throw. If it does not, then it
* throws. An error class and a string that should be included in the
* error message can also be asserted. */
export function assertThrows<E extends Error = Error>(
fn: () => unknown,
// deno-lint-ignore no-explicit-any
ErrorClass: new (...args: any[]) => E,
msgIncludes?: string,
msg?: string,
): E;
/** @deprecated Use assertThrows(fn, msg) instead, which now returns thrown
* value and you can assert on it. */
export function assertThrows(
fn: () => unknown,
errorCallback: (e: Error) => unknown,
msg?: string,
): Error;
export function assertThrows<E extends Error = Error>(
fn: () => unknown,
errorClassOrCallbackOrMsg?:
// deno-lint-ignore no-explicit-any
| (new (...args: any[]) => E)
| ((e: Error) => unknown)
| string,
msgIncludesOrMsg?: string,
msg?: string,
): E | Error | unknown {
// deno-lint-ignore no-explicit-any
let ErrorClass: (new (...args: any[]) => E) | undefined = undefined;
let msgIncludes: string | undefined = undefined;
let errorCallback: ((e: Error) => unknown) | undefined = undefined;
let err;
if (typeof errorClassOrCallbackOrMsg !== "string") {
if (
errorClassOrCallbackOrMsg === undefined ||
errorClassOrCallbackOrMsg.prototype instanceof Error ||
errorClassOrCallbackOrMsg.prototype === Error.prototype
) {
// deno-lint-ignore no-explicit-any
ErrorClass = errorClassOrCallbackOrMsg as new (...args: any[]) => E;
msgIncludes = msgIncludesOrMsg;
} else {
errorCallback = errorClassOrCallbackOrMsg as (e: Error) => unknown;
msg = msgIncludesOrMsg;
}
} else {
msg = errorClassOrCallbackOrMsg;
}
let doesThrow = false;
const msgToAppendToError = msg ? `: ${msg}` : ".";
try {
fn();
} catch (error) {
if (ErrorClass || errorCallback) {
if (error instanceof Error === false) {
throw new AssertionError("A non-Error object was thrown.");
}
assertIsError(
error,
ErrorClass,
msgIncludes,
msg,
);
if (typeof errorCallback === "function") {
errorCallback(error);
}
}
err = error;
doesThrow = true;
}
if (!doesThrow) {
msg = `Expected function to throw${msgToAppendToError}`;
throw new AssertionError(msg);
}
return err;
}
/** Executes a function which returns a promise, expecting it to reject. */
export function assertRejects(
fn: () => PromiseLike<unknown>,
msg?: string,
): Promise<unknown>;
/** Executes a function which returns a promise, expecting it to reject.
* If it does not, then it throws. An error class and a string that should be
* included in the error message can also be asserted. */
export function assertRejects<E extends Error = Error>(
fn: () => PromiseLike<unknown>,
// deno-lint-ignore no-explicit-any
ErrorClass: new (...args: any[]) => E,
msgIncludes?: string,
msg?: string,
): Promise<E>;
/** @deprecated Use assertRejects(fn, msg) instead, which now returns rejected value
* and you can assert on it. */
export function assertRejects(
fn: () => PromiseLike<unknown>,
errorCallback: (e: Error) => unknown,
msg?: string,
): Promise<Error>;
export async function assertRejects<E extends Error = Error>(
fn: () => PromiseLike<unknown>,
errorClassOrCallbackOrMsg?:
// deno-lint-ignore no-explicit-any
| (new (...args: any[]) => E)
| ((e: Error) => unknown)
| string,
msgIncludesOrMsg?: string,
msg?: string,
): Promise<E | Error | unknown> {
// deno-lint-ignore no-explicit-any
let ErrorClass: (new (...args: any[]) => E) | undefined = undefined;
let msgIncludes: string | undefined = undefined;
let errorCallback: ((e: Error) => unknown) | undefined = undefined;
let err;
if (typeof errorClassOrCallbackOrMsg !== "string") {
if (
errorClassOrCallbackOrMsg === undefined ||
errorClassOrCallbackOrMsg.prototype instanceof Error ||
errorClassOrCallbackOrMsg.prototype === Error.prototype
) {
// deno-lint-ignore no-explicit-any
ErrorClass = errorClassOrCallbackOrMsg as new (...args: any[]) => E;
msgIncludes = msgIncludesOrMsg;
} else {
errorCallback = errorClassOrCallbackOrMsg as (e: Error) => unknown;
msg = msgIncludesOrMsg;
}
} else {
msg = errorClassOrCallbackOrMsg;
}
let doesThrow = false;
let isPromiseReturned = false;
const msgToAppendToError = msg ? `: ${msg}` : ".";
try {
const possiblePromise = fn();
if (
possiblePromise &&
typeof possiblePromise === "object" &&
typeof possiblePromise.then === "function"
) {
isPromiseReturned = true;
await possiblePromise;
}
} catch (error) {
if (!isPromiseReturned) {
throw new AssertionError(
`Function throws when expected to reject${msgToAppendToError}`,
);
}
if (ErrorClass || errorCallback) {
if (error instanceof Error === false) {
throw new AssertionError("A non-Error object was rejected.");
}
assertIsError(
error,
ErrorClass,
msgIncludes,
msg,
);
if (typeof errorCallback == "function") {
errorCallback(error);
}
}
err = error;
doesThrow = true;
}
if (!doesThrow) {
throw new AssertionError(
`Expected function to reject${msgToAppendToError}`,
);
}
return err;
}
/** Use this to stub out methods that will throw when invoked. */
export function unimplemented(msg?: string): never {
throw new AssertionError(msg || "unimplemented");
}
/** Use this to assert unreachable code. */
export function unreachable(): never {
throw new AssertionError("unreachable");
}