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Is there an easy way to assert a structure that has some required fields and some optional fields. And have it fail if there are any other unknown fields.

This works but I'm just wondering if there is a better way:

export default class Directive {
    constructor(options: DirectiveOptions) {
        this.selector = options.selector;
        this.bind = options.bind;
    }
}

var DirectiveOptions = assert.define('DirectiveOptions', function(options) {
    //Required fields
    assert(options).is(assert.structure({
        selector: assert.string
    }));

    //Optional fields
    if(options.bind) {
        assert.type(options.bind, Object);
    }

    for(var key in options) {
        if (options.hasOwnProperty(key)) {
            if(key !== 'selector' && key !== 'bind') {
                assert.fail(`${key} is not a valid directive field`);
            }
        }
    }
});

On an unrelated note any idea what I need to use assert.string instead of just string. I'm transpiling with Traceur 0.0.74.

Thanks

I should be able to require that a value is exactly the type I specify, and expect it to throw if given null.

var val = null;
assert.type(val, assert.string);

That assertion passes in the current implementation. It would be nice be able to indicate that a value is nullable: assert.type(val, assert.string, true);

Or if we wanted to extend the language to support this: assert.type(?val, assert.string); or non-nullable: assert.type(!val, assert.string);.

There should be a dist file that exports the assert function on window. This is useful if you want to use this library for type assertions with traceur, but don't want to migrate your whole angular-project to use requirejs :)

E.g. the following code would report a type error:

  static assert(obj) {
    assert(obj).is(assert.structureOf({
      createRootView: Function
    }));
  }

The real problem was the typo: It needs to be assert.structure instead of assert.structureOf. However, the error that assert generated was misleading.

Reproduction:

1. Checkout https://github.com/angular/templating/tree/18411a1729b1d896593a29c9c11409f0ea6bf2bd
2. In annotations#L37 add the line assert(obj).is(assert.string, Object)
3. run karma start

Trying to apply Type Assertions for a function that takes optional arguments. when the optional arguments are not provided, it throws errors. will it be nice if assert.argumentTypes check and only apply type checking if optional argument is not undefined?
in the example below, value argument is optional and type is number.
My suggestion is, validate type only if an optional argument is supplied.

export class EnumItem {
    // constructor(name: string, {value} = {}, value: number) { //TODO want to use this 
    constructor(name: string, {value = Infinity}, value: number) { //workaround
        this.name  = name;
        // this.value = (value) ? value: Symbol(name);  //want to use this 
        this.value = (value === Infinity) ? Symbol(name) : value; //workaround


        delete arguments[1].value;
        Object.assign(this, arguments[1]);

        Object.freeze(this);
    }

    toString() {
        return this.name;
    }

    valueOf() {
        return this.value;
    }
}
console.log('EnumItem1', new EnumItem('xname',{value:2}));
console.log('EnumItem2', new EnumItem('xname',{ description:'ssss'})); 

When using assert.is, I'm running into a Maximum Call Stack Exceeded RangeError when the value is of type Document. All other types work fine. This is because prettyprint is seeing it as typeof "object" and is trying to recurse over its properties to print them. I can submit a fix for this later.

var doc = document.implementation.createDocument(null, 'doc');
assert(doc).is(DataView, Blob, Document);