unexpected/lib/Assertion.js

Extensible BDD assertion toolkit

var createStandardErrorMessage = require('./createStandardErrorMessage');

function Assertion(expect, subject, testDescription, flags, alternations, args) {
    this.expect = expect;
    this.subject = subject;
    this.testDescription = testDescription;
    this.flags = flags;
    this.alternations = alternations;
    this.args = args;
    this.errorMode = 'default';
}

Assertion.prototype.standardErrorMessage = function (options) {
    return createStandardErrorMessage(this.expect.output.clone(), this.expect, this.subject, this.testDescription, this.args, options);
};

Assertion.prototype.shift = function (subject, assertionIndex) {
    if (arguments.length === 3) {
        // The 3-argument syntax for Assertion.prototype.shift is deprecated, please omit the first (expect) arg
        subject = arguments[1];
        assertionIndex = arguments[2];
    }
    var rest = this.args.slice(assertionIndex);
    this.args[assertionIndex] = this.expect.output.clone().error(this.args[assertionIndex]);

    var nextArgumentType = this.expect.findTypeOf(rest[0]);
    if (nextArgumentType.is('expect.it')) {
        return rest[0](subject);
    } else if (nextArgumentType.is('string')) {
        return this.expect.apply(this.expect, [subject].concat(rest));
    } else {
        throw new Error('The "' + this.testDescription + '" assertion requires parameter #' + (assertionIndex + 2) + ' to be an expect.it function or a string specifying an assertion to delegate to');
    }
};

module.exports = Assertion;