`expect` return value can't be reused with `.to.have.property`.

[anko]

Here's a minimal illustration in Mocha:

var expect = require("expect.js");
describe("", function() {
    specify("", function() {

        var y = expect({ a : 1, b : 2 });
        y.to.have.property("a", 1);         // This is OK.
        y.to.have.property("b", 2);         // Mocha outputs "Error: expected 1
                                            // to have a property 'b'".

    });
});

I'm reusing expect's return value. Why is expect.js expecting 1 to have a property b?

The issue seems to be with .to.have.property, as using other assertions works fine:

        var x = expect(1);
        x.to.be.equal(1);                   // This is OK.
        x.to.not.be.equal(0);               // This is OK too.