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promise.test.js
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promise.test.js
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"use strict";
const assert = require("assert");
const P = require("..");
const describe = global.describe;
const it = global.it;
class MyError extends Error {}
describe("Promise", () => {
describe(".then", () => {
it("should be able to use as promise", () => {
return new P(resolve => resolve())
.then(() => P.resolve(1))
.then(res => assert.strictEqual(res, 1));
});
});
describe(".catch", () => {
it("should be able to catch without a predicate", () => {
return P
.reject(new Error())
.catch(() => "test")
.then(res => assert.strictEqual(res, "test"));
});
it("should be able to catch a custom error", () => {
return P
.reject(new MyError())
.catch(MyError, () => {});
});
it("should not catch error of incorrect type", () => {
const fnErr = new Error();
return P
.reject(fnErr)
.catch(MyError, () => {})
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
it("should catch with predicate function", () => {
return P
.reject(new Error("test"))
.catch(err => err.message === "test", () => {});
});
it("should not catch error with failing predicate function", () => {
const fnErr = new Error();
return P
.reject(fnErr)
.catch(() => false, () => {})
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
it("should be able to chain catches", () => {
return P
.reject(new TypeError())
.catch(MyError, () => P.reject(new Error("should not run")))
.catch(TypeError, () => {});
});
});
describe(".promisify", () => {
it("should be able to promisify callback method", () => {
const fn = P.promisify((x, cb) => cb(null, x));
return fn(1)
.then(res => assert.strictEqual(res, 1));
});
it("should reject callback method with error", () => {
const fn = P.promisify(cb => cb(new Error("Callback error")));
return fn()
.then(() => Promise.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err.message, "Callback error"));
});
it("should convert multiple arguments in callback to array", () => {
const fn = P.promisify((x, y, cb) => cb(null, x, y));
return fn(1, 2)
.then(res => assert.deepEqual(res, [1, 2]));
});
it("should be able to pass context to promisify", () => {
const fn = P.promisify(function callbackMethod(cb) {
cb(null, this);
}, 1);
return fn()
.then(res => assert.strictEqual(res, 1));
});
it("should use dynamic context if not specified", () => {
const o = {
fn : P.promisify(function callbackMethod(cb) {
cb(null, this);
})
};
return o.fn()
.then(res => assert.strictEqual(res, o));
});
});
describe(".promisifyAll", () => {
it("should promisify all methods on an object", () => {
const add = (x, y, cb) => cb(null, x + y);
const o = P.promisifyAll({
addOne : add.bind(null, 1),
addTwo : add.bind(null, 2)
});
return P.all([
o.addOneAsync(1).then(x => assert.strictEqual(x, 2)),
o.addTwoAsync(1).then(x => assert.strictEqual(x, 3))
]);
});
it("should return original object", () => {
const o = {};
assert.strictEqual(P.promisifyAll(o), o);
});
it("should not attempt to promisify values that are not functions", () => {
const o = P.promisifyAll({
add : (x, y, cb) => cb(null, x + y),
str : "test"
});
assert.deepEqual(Object.keys(o).sort(), ["add", "addAsync", "str"]);
});
it("should be able to specify suffix", () => {
const o = P.promisifyAll({
add : (x, y, cb) => cb(null, x + y)
}, {
suffix : "Promise"
});
return o
.addPromise(1, 2)
.then(x => assert.strictEqual(x, 3));
});
it("should be able to overwrite original method with no suffix", () => {
const o = P.promisifyAll({
add : (x, y, cb) => cb(null, x + y)
}, {
suffix : ""
});
return o
.add(1, 2)
.then(x => assert.strictEqual(x, 3));
});
it("should be able to reject promisified methods", () => {
const fnErr = new Error("Test error");
const o = P.promisifyAll({
fn : cb => cb(fnErr)
});
return o
.fnAsync()
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
it("should be able to filter methods", () => {
const o = P.promisifyAll({
a : cb => cb(),
b : cb => cb()
}, {
filter : name => name === "a"
});
assert.deepEqual(Object.keys(o).sort(), ["a", "aAsync", "b"]);
});
it("should provide correct arguments to filter", () => {
const fn = cb => cb();
const o = { fn };
P.promisifyAll(o, {
filter : (name, method, obj) => {
assert.strictEqual(name, "fn");
assert.strictEqual(method, fn);
assert.strictEqual(obj, o);
}
})
});
it("should have correct binding context on promisified methods", () => {
const o = P.promisifyAll({
fn(cb) {
assert.strictEqual(this, o);
cb();
}
});
return o.fnAsync();
});
});
describe(".try", () => {
it("should return a promise from a synchronous function", () => {
return P
.try(() => "test")
.then(res => assert.strictEqual(res, "test"));
});
it("should return a rejected promise on synchronous exception", () => {
const fnErr = new Error("Test error");
return P
.try(() => {
throw fnErr;
})
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
it("should wait for a resolved promise", () => {
return P
.try(() => P.resolve("test"))
.then(res => assert.strictEqual(res, "test"));
});
it("should wait for a rejected promise", () => {
const fnErr = new Error("Test error");
return P
.try(() => P.reject(fnErr))
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
});
describe(".method", () => {
it("should return a method that returns a promise from a synchronous function", () => {
return P
.method(() => "test")()
.then(res => assert.strictEqual(res, "test"));
});
it("should return a rejected promise on synchronous exception", () => {
const fnErr = new Error("Test error");
return P
.method(() => {
throw fnErr;
})()
.then(() => P.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err, fnErr));
});
it("should pass arguments to promisified function", () => {
return P
.method((a, b, c) => [a, b, c])(1, 2, 3)
.then(res => assert.deepEqual(res, [1, 2, 3]));
});
it("should pass `this` context to promisified function", () => {
const o = {
fn() {
return this;
}
};
return Object
.assign(o, {
fn : P.method(o.fn)
})
.fn()
.then(res => assert.strictEqual(res, o));
});
});
describe(".fromCallback", () => {
it("should be able to use fromCallback to promisify", () => {
return P
.fromCallback(cb => cb(null, 1))
.then(res => assert.strictEqual(res, 1));
});
it("should reject fromCallback with error", () => {
return P
.fromCallback(cb => cb(new Error("Callback error")))
.then(() => Promise.reject(new Error("Did not reject")))
.catch(err => assert.strictEqual(err.message, "Callback error"));
});
});
describe(".toCallback", () => {
it("should be able to convert resolved promise to callback", cb => {
P.resolve(1)
.toCallback((err, res) => {
assert.strictEqual(err, null);
assert.strictEqual(res, 1);
cb();
});
});
it("should be able to convert rejected promise to callback", cb => {
const testErr = new Error("Test error");
P.reject(testErr)
.toCallback((err, res) => {
assert.strictEqual(err, testErr);
assert.strictEqual(res, undefined);
cb();
});
});
});
describe(".extend", () => {
it("should be able to extend existing Promise implementation", () => {
class APromise extends Promise {}
assert.strictEqual(P.extend(APromise), APromise);
assert.strictEqual(APromise.promisify, P.promisify);
return APromise
.resolve()
.return(1)
.tap(res => assert.strictEqual(res, 1))
.then(res => assert.strictEqual(res, 1));
});
});
});