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nodejs/test/parallel/test-util-inherits.js
Ruben Bridgewater ac2fc0dd5f
errors: improve ERR_INVALID_ARG_TYPE
ERR_INVALID_ARG_TYPE is the most common error used throughout the
code base. This improves the error message by providing more details
to the user and by indicating more precisely which values are allowed
ones and which ones are not.

It adds the actual input to the error message in case it's a primitive.
If it's a class instance, it'll print the class name instead of
"object" and "falsy" or similar entries are not named "type" anymore.

PR-URL: https://github.com/nodejs/node/pull/29675
Reviewed-By: Rich Trott <rtrott@gmail.com>
2019-12-20 03:10:13 +01:00

111 lines
2.3 KiB
JavaScript

'use strict';
const common = require('../common');
const assert = require('assert');
const { inherits } = require('util');
// Super constructor
function A() {
this._a = 'a';
}
A.prototype.a = function() { return this._a; };
// One level of inheritance
function B(value) {
A.call(this);
this._b = value;
}
inherits(B, A);
B.prototype.b = function() { return this._b; };
assert.deepStrictEqual(
Object.getOwnPropertyDescriptor(B, 'super_'),
{
value: A,
enumerable: false,
configurable: true,
writable: true
}
);
const b = new B('b');
assert.strictEqual(b.a(), 'a');
assert.strictEqual(b.b(), 'b');
assert.strictEqual(b.constructor, B);
// Two levels of inheritance
function C() {
B.call(this, 'b');
this._c = 'c';
}
inherits(C, B);
C.prototype.c = function() { return this._c; };
C.prototype.getValue = function() { return this.a() + this.b() + this.c(); };
assert.strictEqual(C.super_, B);
const c = new C();
assert.strictEqual(c.getValue(), 'abc');
assert.strictEqual(c.constructor, C);
// Inherits can be called after setting prototype properties
function D() {
C.call(this);
this._d = 'd';
}
D.prototype.d = function() { return this._d; };
inherits(D, C);
assert.strictEqual(D.super_, C);
const d = new D();
assert.strictEqual(d.c(), 'c');
assert.strictEqual(d.d(), 'd');
assert.strictEqual(d.constructor, D);
// ES6 classes can inherit from a constructor function
class E {
constructor() {
D.call(this);
this._e = 'e';
}
e() { return this._e; }
}
inherits(E, D);
assert.strictEqual(E.super_, D);
const e = new E();
assert.strictEqual(e.getValue(), 'abc');
assert.strictEqual(e.d(), 'd');
assert.strictEqual(e.e(), 'e');
assert.strictEqual(e.constructor, E);
// Should throw with invalid arguments
common.expectsError(function() {
inherits(A, {});
}, {
code: 'ERR_INVALID_ARG_TYPE',
type: TypeError,
message: 'The "superCtor.prototype" property must be of type object. ' +
'Received undefined'
});
common.expectsError(function() {
inherits(A, null);
}, {
code: 'ERR_INVALID_ARG_TYPE',
type: TypeError,
message: 'The "superCtor" argument must be of type function. ' +
'Received null'
});
common.expectsError(function() {
inherits(null, A);
}, {
code: 'ERR_INVALID_ARG_TYPE',
type: TypeError,
message: 'The "ctor" argument must be of type function. Received null'
});