Simple UI test runner for stats example program

simple-ui-test-runner.js

var testRunner = (function () {
    'use strict';
    
    function isMatch (expectedValue, actualValue) {
        var equalMatch = expectedValue === actualValue;
        var NaNMatch = Number.isNaN(expectedValue) && Number.isNaN(actualValue);
        
        return equalMatch || NaNMatch;
    }
    
    function testUi(sample, expectedMean, expectedStandardDeviation) {
        document.getElementById('sample').value = sample.join(', ');
        document.getElementById('compute').click();
        
        var mean = parseFloat(document.getElementById('mean').innerText);
        var standardDeviation = parseFloat(document.getElementById('standard-deviation').innerText);
        
        if(!isMatch(mean, expectedMean)) {
            throw new Error('Expected mean value of ' + expectedMean + ' but got ' + mean);
        }

        if(!isMatch(standardDeviation, expectedStandardDeviation)) {
            throw new Error('Expected standard deviation value of ' + expectedStandardDeviation + ' but got ' + standardDeviation);
        }
        
        return 'Test passed without error';
    }
    
    return {
        testUi: testUi
    };
    
})();