413 lines
12 KiB
JavaScript
413 lines
12 KiB
JavaScript
// # Assert.js
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// A run-time type assertion library for JavaScript. Designed to be used with [Traceur](https://github.com/google/traceur-compiler).
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// - [Basic Type Check](#basic-type-check)
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// - [Custom Check](#custom-check)
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// - [Primitive Values](#primitive-values)
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// - [Describing more complex types](#describing-more-complex-types)
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// - [assert.arrayOf](#assert-arrayof)
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// - [assert.structure](#assert-structure)
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// - [Integrating with Traceur](#integrating-with-traceur)
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// Note: `assert` gets automatically included by traceur!
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export function main() {
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describe('prettyPrint', () => {
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class Type {};
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it('should limit the number of printed properties', () => {
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var o = {};
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for (var i = 0; i < 100; i++) {
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o['p_' + i] = i;
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}
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try {
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assert.type(o, Type);
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throw 'fail!';
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} catch (e) {
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expect(e.message.indexOf('p_0')).toBeGreaterThan(-1);
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expect(e.message.indexOf('...')).toBeGreaterThan(-1);
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expect(e.message.indexOf('p_20')).toBe(-1);
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}
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});
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it('should limit the depth of printed properties', () => {
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var o = {l1: {l2: {l3: {l4: {l5: {l6: 'deep'}}}}}};
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expect(() => {
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assert.type(o, Type);
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}).toThrowError('Expected an instance of Type, got {l1: {l2: {l3: {l4: [...]}}}}!');
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});
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});
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// ## Basic Type Check
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// By default, `instanceof` is used to check the type.
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//
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// Note that you can use `assert.type()` in unit tests or anywhere in your code.
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// Most of the time, you will use it with Traceur.
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// Jump to the [Traceur section](#integrating-with-traceur) to see an example of that.
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describe('basic type check', function() {
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class Type {}
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it('should pass', function() {
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assert.type(new Type(), Type);
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});
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it('should fail', function() {
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expect(() => assert.type(123, Type))
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.toThrowError('Expected an instance of Type, got 123!');
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});
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it('should allow null', function() {
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assert.type(null, Type);
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});
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});
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// ## Custom Check
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// Often, `instanceof` is not flexible enough.
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// In that case, your type can define its own `assert` method which will be used instead.
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//
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// See [Describing More Complex Types](#describing-more-complex-types) for examples how to
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// define custom checks using `assert.define()`.
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describe('custom check', function() {
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class Type {}
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// the basic check can just return true/false, without specifying any reason
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it('should pass when returns true', function() {
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Type.assert = function(value) {
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return true;
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};
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assert.type({}, Type);
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});
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it('should fail when returns false', function() {
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Type.assert = function(value) {
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return false;
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};
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expect(() => assert.type({}, Type))
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.toThrowError('Expected an instance of Type, got {}!');
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});
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// Using `assert.fail()` allows to report even multiple errors.
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it('should fail when calls assert.fail()', function() {
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Type.assert = function(value) {
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assert.fail('not smart enough');
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assert.fail('not blue enough');
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};
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expect(() => assert.type({}, Type))
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.toThrowError('Expected an instance of Type, got {}!\n' +
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' - not smart enough\n' +
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' - not blue enough');
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});
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it('should fail when throws an exception', function() {
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Type.assert = function(value) {
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throw new Error('not long enough');
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};
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expect(function() {
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assert.type(12345, Type);
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}).toThrowError('Expected an instance of Type, got 12345!\n' +
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' - not long enough');
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});
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});
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// ## Primitive Values
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// You don't want to check primitive values (such as strings, numbers, or booleans) using `typeof` rather than
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// `instanceof`.
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//
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// Again, you probably won't write this code and rather use Traceur to do it for you, simply based on type annotations.
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describe('primitive value check', function() {
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var primitive = $traceurRuntime.type;
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describe('string', function() {
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it('should pass', function() {
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assert.type('xxx', primitive.string);
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});
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it('should fail', function() {
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expect(() => assert.type(12345, primitive.string))
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.toThrowError('Expected an instance of string, got 12345!');
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});
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it('should allow null', function() {
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assert.type(null, primitive.string);
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});
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});
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describe('number', function() {
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it('should pass', function() {
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assert.type(123, primitive.number);
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});
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it('should fail', function() {
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expect(() => assert.type(false, primitive.number))
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.toThrowError('Expected an instance of number, got false!');
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});
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it('should allow null', function() {
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assert.type(null, primitive.number);
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});
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});
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describe('boolean', function() {
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it('should pass', function() {
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expect(assert.type(true, primitive.boolean)).toBe(true);
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expect(assert.type(false, primitive.boolean)).toBe(false);
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});
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it('should fail', function() {
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expect(() => assert.type(123, primitive.boolean))
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.toThrowError('Expected an instance of boolean, got 123!');
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});
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it('should allow null', function() {
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assert.type(null, primitive.boolean);
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});
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});
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});
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// ## Describing more complex types
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//
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// Often, a simple type check using `instanceof` or `typeof` is not enough.
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// That's why you can define custom checks using this DSL.
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// The goal was to make them easy to compose and as descriptive as possible.
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// Of course you can write your own DSL on the top of this.
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describe('define', function() {
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// If the first argument to `assert.define()` is a type (function), it will define `assert` method on that function.
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//
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// In this example, being a type of Type means being a either a function or object.
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it('should define assert for an existing type', function() {
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class Type {}
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assert.define(Type, function(value) {
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assert(value).is(Function, Object);
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});
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assert.type({}, Type);
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assert.type(function() {}, Type);
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expect(() => assert.type('str', Type))
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.toThrowError('Expected an instance of Type, got "str"!\n' +
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' - "str" is not instance of Function\n' +
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' - "str" is not instance of Object');
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});
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// If the first argument to `assert.define()` is a string,
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// it will create an interface - basically an empty class with `assert` method.
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it('should define an interface', function() {
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var User = assert.define('MyUser', function(user) {
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assert(user).is(Object);
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});
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assert.type({}, User);
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expect(() => assert.type(12345, User))
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.toThrowError('Expected an instance of MyUser, got 12345!\n' +
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' - 12345 is not instance of Object');
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});
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// Here are a couple of more APIs to describe your custom types...
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//
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// ### assert.arrayOf
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// Checks if the value is an array and if so, it checks whether all the items are one the given types.
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// These types can be composed types, not just simple ones.
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describe('arrayOf', function() {
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var Titles = assert.define('ListOfTitles', function(value) {
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assert(value).is(assert.arrayOf(assert.string, assert.number));
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});
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it('should pass', function () {
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assert.type(['one', 55, 'two'], Titles);
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});
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it('should fail when non-array given', function () {
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expect(() => assert.type('foo', Titles))
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.toThrowError('Expected an instance of ListOfTitles, got "foo"!\n' +
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' - "foo" is not instance of array of string/number\n' +
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' - "foo" is not instance of Array');
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});
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it('should fail when an invalid item in the array', function () {
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expect(() => assert.type(['aaa', true], Titles))
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.toThrowError('Expected an instance of ListOfTitles, got ["aaa", true]!\n' +
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' - ["aaa", true] is not instance of array of string/number\n' +
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' - true is not instance of string\n' +
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' - true is not instance of number');
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});
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});
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// ### assert.structure
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// Similar to `assert.arrayOf` which checks a content of an array,
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// `assert.structure` checks if the value is an object with specific properties.
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describe('structure', function() {
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var User = assert.define('MyUser', function(value) {
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assert(value).is(assert.structure({
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name: assert.string,
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age: assert.number
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}));
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});
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it('should pass', function () {
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assert.type({name: 'Vojta', age: 28}, User);
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});
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it('should fail when non-object given', function () {
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expect(() => assert.type(123, User))
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.toThrowError('Expected an instance of MyUser, got 123!\n' +
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' - 123 is not instance of object with properties name, age\n' +
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' - 123 is not instance of Object');
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});
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it('should fail when an invalid property', function () {
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expect(() => assert.type({name: 'Vojta', age: true}, User))
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.toThrowError('Expected an instance of MyUser, got {name: "Vojta", age: true}!\n' +
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' - {name: "Vojta", age: true} is not instance of object with properties name, age\n' +
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' - true is not instance of number');
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});
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});
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});
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// ## Integrating with Traceur
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//
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// Manually calling `assert.type()` in your code is cumbersome. Most of the time, you'll want to
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// have Traceur add the calls to `assert.type()` to your code based on type annotations.
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//
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// This has several advantages:
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// - it's shorter and nicer,
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// - you can easily ignore it when generating production code.
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//
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// You'll need to run Traceur with `--types=true --type-assertions=true --type-assertion-module="path/to/assert"`.
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describe('Traceur', function() {
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describe('arguments', function() {
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function reverse(str: string) {
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return str ? reverse(str.substring(1)) + str[0] : ''
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}
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it('should pass', function() {
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expect(reverse('angular')).toBe('ralugna');
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});
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it('should fail', function() {
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expect(() => reverse(123))
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.toThrowError('Invalid arguments given!\n' +
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' - 1st argument has to be an instance of string, got 123');
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});
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});
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describe('return value', function() {
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function foo(bar): number {
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return bar;
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}
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it('should pass', function() {
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expect(foo(123)).toBe(123);
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});
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it('should fail', function() {
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expect(() => foo('bar'))
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.toThrowError('Expected to return an instance of number, got "bar"!');
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});
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});
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describe('variables', function() {
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it('should pass', function() {
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var count:number = 1;
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});
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it('should fail', function() {
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expect(() => {
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var count: number = true;
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}).toThrowError('Expected an instance of number, got true!');
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});
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});
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describe('void', function() {
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function foo(bar): void {
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return bar;
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}
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it('should pass when not defined', function() {
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function nonReturn(): void {}
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function returnNothing(): void { return; }
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function returnUndefined(): void { return undefined; }
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foo();
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foo(undefined);
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nonReturn();
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returnNothing();
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returnUndefined();
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});
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it('should fail when a value returned', function() {
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expect(() => foo('bar'))
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.toThrowError('Expected to return an instance of void, got "bar"!');
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});
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it('should fail when null returned', function() {
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expect(() => foo(null))
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.toThrowError('Expected to return an instance of void, got null!');
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});
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});
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describe('generics', function() {
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it('should pass', function() {
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var list:Array<string> = [];
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});
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// TODO(tbosch): add assertions based on generics to rtts_assert
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});
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});
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}
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