lib/eslint.js

const isFatal = (fatal, severity) => fatal || severity === 2;

const getUniqueMessages = messages => {
    const jsonValues = messages.map(m => JSON.stringify(m));
    const uniuqeValues = jsonValues.reduce((accum, curr) => {
        if (accum.indexOf(curr) === -1) {
            accum.push(curr);
        }
        return accum;
    }, []);

    return uniuqeValues.map(v => JSON.parse(v));
};

const calculateErrors = messages =>
    messages.reduce((acc,  { fatal, severity }) => isFatal(fatal , severity) ? acc + 1: acc, 0);

const calculateWarnings = messages =>
    messages.reduce((acc,  { fatal, severity }) => !isFatal(fatal , severity) ? acc + 1: acc, 0);


const getUniqueIssues = issues => 
    issues.map(({ messages, ...restProps }) => {
        const uniqueMessages = getUniqueMessages(messages);
        const warningCount = calculateWarnings(uniqueMessages);
        const errorCount = calculateErrors(uniqueMessages);

        return {
            ...restProps,
            messages: uniqueMessages,
            errorCount,
            warningCount,
        };
    });

module.exports = {
    getUniqueIssues,
    getUniqueMessages,
    isFatal,
};