coverify/index.js

code coverage browserify transform

'use strict';

var falafel = require('falafel');
var through = require('through2');
var sourceMap = require('source-map');
var convertSourceMap = require('convert-source-map');
var slash = require('slash');

module.exports = function (file, opts) {
    if (typeof file === 'object') {
        opts = file;
        file = undefined;
    }
    if (!opts) { opts = {}; }
    var outputFn = opts.output || 'console.log';

    var expected = [];

    var chunks = [];
    var stream = through(write, end);
    return stream;

    function write(buf, enc, next) { chunks.push(buf); next(); }

    function end() {
        var body = Buffer.concat(chunks)
            .toString('utf8')
            .replace(/^#!/, '//#!');
        if (file.match(/\.json$/)) {
            this.push('module.exports=' + body);
            this.push(null);
            return;
        }

        var fopts = {
            locations: true,
            ecmaVersion: opts.ecmaVersion || 9
        };
        try { var src = String(falafel(body, fopts, walk)); } catch (err) { return onerror(err, file, body); }
        var sfile = JSON.stringify(JSON.stringify(file));

        var origBody = body;
        var bodySourceMap = convertSourceMap.fromSource(body);
        if (bodySourceMap && bodySourceMap.sourcemap.mappings) {
            bodySourceMap = new sourceMap.SourceMapConsumer(bodySourceMap.sourcemap);
            origBody = bodySourceMap.sourceContentFor(slash(file));
            var originalLoc = function originalLocation(loc) {
                var pos = bodySourceMap.originalPositionFor(loc);
                if (pos.line && pos.column) {
                    return { line: pos.line, column: pos.column };
                }
            };
            expected = expected.map(function (loc) {
                var origStart = originalLoc(loc.start);
                var origEnd = originalLoc(loc.end);
                if (origStart && origEnd) {
                    return { start: originalLoc(loc.start), end: originalLoc(loc.end) };
                } else { return false; }
            });
        }

        var lines = origBody.split('\n');
        var lineOffsets = [];
        var offset = 0;
        for (var i = 0; i < lines.length; i++) {
            lineOffsets[i] = offset;
            offset += lines[i].length + 1;
        }
        expected = expected.map(function (loc) {
            if (!loc) { return false; }
            return [
                lineOffsets[loc.start.line - 1] + loc.start.column,
                lineOffsets[loc.end.line - 1] + loc.end.column
            ];
        });

        /* eslint-disable no-useless-concat */
        this.push(outputFn + '("COVERAGE " + ' + sfile + ' + " " + ' + JSON.stringify(JSON.stringify(expected)) + ');' + 'var __coverage = ' + JSON.stringify(expected.reduce(function (acc, x, ix) {
            acc[ix] = x;
            return acc;
        }, {})) + ';' + 'var __coverageFunction = function () {' + 'var a=[].slice.call(arguments);' + 'a.splice(-1, 0, "__coverageWrap");' + 'var f=Function.apply(this, a);' + 'return function(){' + 'var b=[].slice.call(arguments);' + 'b.push(__coverageWrap);' + 'return f.apply(this, b);' + '}' + '};' + '__coverageFunction.prototype = Function.prototype;' + 'var __coverageWrap = function (index) {' + 'if (__coverage[index]) ' + outputFn + '("COVERED " + ' + sfile + ' + " " + index);' + 'delete __coverage[index];' + 'return function (x) { return x }' + '};' + '(function (Function) {\n');
        /* eslint-enable no-useless-concat */
        this.push(src);
        this.push('\n})(__coverageFunction)');
        this.push(null);
    }

    function walk(node) {
        var index = expected.length;
        if (node.type === 'VariableDeclarator' && node.init) {
            expected.push(node.init.loc);
            node.init.update('(__coverageWrap(' + index + ')(' + node.init.source() + '))');
        } else if ((/Expression$/).test(node.type) && node.parent.type !== 'UnaryExpression' && node.parent.type !== 'AssignmentExpression' && node.parent.type !== 'UpdateExpression' && (node.type !== 'MemberExpression' || node.parent.type !== 'CallExpression'
        )) {
            expected.push(node.loc);
            node.update('(__coverageWrap(' + index + ')(' + node.source() + '))');
        } else if ((node.type === 'ExpressionStatement' || node.type === 'VariableDeclaration') && node.parent.type !== 'ForStatement' && node.parent.type !== 'ForInStatement') {
            var s = '{ __coverageWrap(' + index + ');' + node.source() + '\n}';
            if (node.parent.type === 'IfStatement') {
                node.update(s);
            } else { node.update(s + ';'); }
            expected.push(node.loc);
        } else if (node.type === 'ReturnStatement') {
            node.update('return __coverageWrap(' + index + ')(function () {' + node.source() + '}).apply(this, [].slice.call(arguments));');
            expected.push(node.loc);
        }
    }

    function onerror(err, file, body) {
        if (err && err.lineNumber !== undefined) {
            var lines = body.split('\n');
            var line = lines[err.lineNumber - 1];

            var msg = err.description + '\n\n' + file + ':' + err.lineNumber + '\n' + line + '\n' + Array(err.column).join(' ') + '^';
            var e = new Error(msg);
            e.lineNumber = err.lineNumber;
            e.column = err.column;
            e.line = line;
            stream.emit('error', e);
        } else { stream.emit('error', err); }
    }
};