chai-somewhere/chai-somewhere.js

Chai Somewhere is a Chai plugin that lets you test whether an assertion applies somewhere within a test object.

var traverse = require('traverse');

module.exports = function (chai, utils) {

    utils.addProperty(chai.Assertion.prototype, 'somewhere', setSomewhereFlag);
    utils.addProperty(chai.Assertion.prototype, 'anywhere', setSomewhereFlag);

    utils.overwriteChainableMethod(chai.Assertion.prototype, 'contain', overwriteWithTypeFilter(isArrayOrString), keepSameBehaviour);
    utils.overwriteChainableMethod(chai.Assertion.prototype, 'contains', overwriteWithTypeFilter(isArrayOrString), keepSameBehaviour);
    utils.overwriteChainableMethod(chai.Assertion.prototype, 'include', overwriteWithTypeFilter(isArrayOrString), keepSameBehaviour);
    utils.overwriteChainableMethod(chai.Assertion.prototype, 'includes', overwriteWithTypeFilter(isArrayOrString), keepSameBehaviour);

    utils.overwriteMethod(chai.Assertion.prototype, 'property', overwriteWithTypeFilter(isArrayOrObject));

    function setSomewhereFlag() {
        utils.flag(this, 'somewhere', true);
        return this;
    }

    function isArrayOrObject(object) {
        return Array.isArray(object) || typeof object === 'object';
    }

    function isArrayOrString(object) {
        return Array.isArray(object) || object instanceof Array || typeof object === 'string';
    }

    function keepSameBehaviour(_super) {
        return _super;
    }

    function overwriteWithTypeFilter(typeFilter) {
        return function (_super) {
            return function () {
                if (utils.flag(this, 'somewhere')) {
                    performSomewhereAssertion(this, _super, arguments, typeFilter);
                } else {
                    _super.apply(this, arguments);
                }
            };
        };
    }

    function performSomewhereAssertion(assertion, overwrittenMethod, testArguments, typeFilter) {
        var object = utils.flag(assertion, 'object');
        if (utils.flag(assertion, 'negate')) {
            checkAssertionNegativeCase(assertion, object, overwrittenMethod, testArguments, typeFilter);
        } else {
            checkAssertionPositiveCase(assertion, object, overwrittenMethod, testArguments, typeFilter);
        }
    }

    function checkAssertionNegativeCase(assertion, object, overwrittenMethod, testArguments, typeFilter) {
        traverse(object).forEach(function (node) {
            utils.flag(assertion, 'object', node);
            if (!typeFilter || typeFilter(node)) {
                silencePropertyCheck(function () {
                    overwrittenMethod.apply(assertion, testArguments)
                });
            }
        });
    }

    // When a key and value are passed to the .property assertion, chai check that the object
    // tested has the provided key. We do not want this check as we don't expect all objects in the
    // graph to contain the key.
    function silencePropertyCheck(assertion) {
        try {
            assertion();
        } catch (error) {
            if (error.message.indexOf('has no property') === -1) {
                throw error;
            }
        }
    }

    function checkAssertionPositiveCase(assertion, object, overwrittenMethod, testArguments, typeFilter) {
        var found = false;
        traverse(object).forEach(function (node) {
            if (!found) {
                if (!typeFilter || typeFilter(node)) {
                    try {
                        utils.flag(assertion, 'object', node);
                        overwrittenMethod.apply(assertion, testArguments);
                        found = true;
                    } catch (ignore) {
                        // Keep looking.
                    }
                }
            }
        });
        if (!found) {
            // Call again with root object to get best error message.
            utils.flag(assertion, 'object', object);
            overwrittenMethod.apply(assertion, testArguments);
        }
    }
};