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remap-istanbul

remap-istanbul

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A package that provides the ability to remap Istanbul code coverage information to its original source positions based on a JavaScript Source Maps v3.

remap-istanbul requires NodeJS 6 or later.

How to get Help

This is covered in depth in the CONTRIBUTING.md document in the repo.

Usage

For information on how to use remap-istanbul with common testing frameworks, please visit the wiki.

There are three main modules that constitute the remap-istanbul package:

  • lib/loadCoverage - does the basic loading of a Istanbul JSON coverage files. It can "merge" several coverage files, for example if you are collecting remote coverage from other environments and combining it together.
  • lib/remap - does the remapping of the coverage information. It iterates through all the files in the coverage information and looks for JavaScript Source Maps which it will then use to remap the coverage information to the original source.
  • lib/writeReport - a wrapper for the Istanbul report writers to output the any final coverage reports.

Command Line

The package includes a command line interface which should be placed into the ./node_modules/.bin/remap-istanbul when the package is installed. The command line interface understands the following argument flags:

Flag Description
-i or --input The path to the coverage input file. For example remap-istanbul --input coverage.json. If omitted, input will be taken from stdin.
-o or --output The path to the remapped coverage output file. For example remap-istanbul --output coverage-final.json. If omitted, json output will be sent to stdout.
-t or --type The type of report the output should be. For example remap-istanbul --output html-report --type html. If omitted, output defaults to json.
-b or --basePath When remapping the source files, instead of using the path in the source map, substitute this this path.
-e or --exclude Pass in a comma seperated string of patterns (exact strings or regexps) to exclude from the output. For example remap-istanbul --output coverage-final.json --exclude node_modules,tests

An example of piping a coverage file to the CLI and writing it out to a file:

$ cat coverage-final.json | ./node_modules/.bin/remap-istanbul -o coverage-remapped.json

An example of generating an HTML report off of remapped coverage:

$ ./node_modules/.bin/remap-istanbul -i coverage-final.json -o html-report -t html

An example of taking the stdin and writing the stdout in the CLI:

$ cat coverage-final.json | ./node_modules/.bin/remap-istanbul > coverage-remap.json

Basic JavaScript

The main CommonJS module provided combines the modules above into a single API which basic usage can look like this:

var remapIstanbul = require('remap-istanbul');
remapIstanbul('coverage-final.json', {
    'json': 'coverage-final.json'
});

This would take the coverage file provided. The function accepts the following arguments:

Argument Type Description
sources Array, string Either an array of strings or a string the represent the JSON Istanbul files to be remapped
reports Object A hash of reports, where the keys are the Istanbul report types and the values are the destination for the report. To send output to the console use the destination null.
returns Promise A promise that is resolved when all the reports are written

AMD

The main modules are provided in AMD for usage (although they utilize amdefine to allow transparent loading by a CommonJS loader such as NodeJS's require - see blow).

lib/loadCoverage

The lib/loadCoverage module would be used something like this:

require([ 'remap-istanbul/lib/loadCoverage' ], function (loadCoverage) {
    var coverage = loadCoverage('coverage-final.json');
    /* or if you have multiple files you want to merge */
    coverage = loadCoverage([ 'coverage-ie.json', 'coverage-chrome.json', 'coverage-firefox.json' ]);
});

The argument signature for loadCoverage is:

Argument Type Description
coverage Array/string Either an array of strings or a string representing the file path to the coverage file(s).
options Object? An object that allows providing alternative methods, mainly used for integration with other systems (e.g. Grunt)
returns Object A coverage object that is ready to be remapped

The options argument can take the following optional properties:

Property Type Default Description
readJSON Function JSON.parse(fs.readFileSync) A function that will synchronously read a file and return a POJO based on the JSON data in the file
warn Function console.warn A function that logs warning messages

lib/remap

Usage of the lib/remap module would look something like this:

require([
    'remap-istanbul/lib/loadCoverage',
    'remap-istanbul/lib/remap'
], function (loadCoverage, remap) {
    var coverage = loadCoverage('coverage-final.json');
    var collector = remap(coverage); /* collector now contains the remapped coverage */
});

If the source map no longer points properly at the source files, you can utilize the basePath option to override the path retrieved from the source map:

require([
    'remap-istanbul/lib/loadCoverage',
    'remap-istanbul/lib/remap'
], function (loadCoverage, remap) {
    var coverage = loadCoverage('coverage-final.json');
    var collector = remap(coverage, {
        basePath: 'some/other/path/to/sources'
    });
});

The argument signature for remap is:

Argument Type Description
coverage Array/Object Either an array of coverage objects or a single coverage object.
options Object? An object that allows providing alternative methods, mainly used for integration with other systems (e.g. Grunt)
returns istanbul/lib/collector An Istanbul coverage collector that is ready to be output

The argument of options can contain the following properties:

Property Type Default Description
basePath String Path found in source map A string to use as the base path for the source locations
exclude String/RegEx/Function undefined If the filename of the source coverage file matches the String or RegEx, it will be skipped while mapping the coverage. Optionally, you can use a function that accepts the filename as the argument, and returns true if the file should be skipped.
readFile Function fs.readFileSync A function that will synchronously read a file
readJSON Function JSON.parse(fs.readFileSync) A function that will synchronously read a file and return a POJO based on the JSON data in the file
warn Function console.warn A function that logs warning messages

lib/writeReport

The lib/writeReport module would be used something like this:

require([
    'remap-istanbul/lib/loadCoverage',
    'remap-istanbul/lib/remap',
    'remap-istanbul/lib/writeReport'
], function (loadCoverage, remap, writeReport) {
    var collector = remap(loadCoverage('coverage-final.json'));
    writeReport(collector, 'json', 'coverage-final.json').then(function () {
        /* do something else now */
    });
});

The writeReport function can take the following arguments:

Argument Type Description
collector istanbul/lib/collector This is an Istanbul coverage collector (usually returned from remap which is to be written out in a report)
reportType string The type of the report. Valid values are: clover, cobertura, html, json-summary, json, file, lcovonly, teamcity, text-lcov, text-summary or text
reportOptions object Options object of key/value pairs to pass to the reporter
dest string, Function The destination file, directory or console logging function that is the destination of the report. Only text-lcov takes the logging function and will default to console.log if no value is passed.
returns Promise A promise that is resolved when the report is written.

CommonJS

If you are not using an AMD loader, that is not a problem for consuming the modules. They also can be loaded in a CommonJS environment:

var loadCoverage = require('remap-istanbul/lib/loadCoverage');
var remap = require('remap-istanbul/lib/remap');
var writeReport = require('remap-istanbul/lib/writeReport');

Grunt Task

You can utilize this package as a Grunt task. After installing it as a package, you need to add the following to your Gruntfile.js:

grunt.loadNpmTasks('remap-istanbul');

The task is a multi-target task and a basic configuration for the task would look something like this:

grunt.initConfig({
    remapIstanbul: {
        build: {
            src: 'coverage-final.json',
            options: {
                reports: {
                    'lcovhtml': 'html-report',
                    'json': 'coverage-final.json'
                }
            }
        }
    }
});

This would take in coverage-final.json, remap it and then output the Istanbul HTML report to html-report and overwrite the original coverage-final.json.

The task also recognizes an abbreviated version of configuration:

grunt.initConfig({
    remapIstanbul: {
        build: {
            files: [ {
                src: 'coverage.json',
                dest: 'tmp/coverage.json',
                type: 'json'
            } ]
        }
    }
});

By default, the grunt task will log warnings/errors to the grunt.log.error. If instead you wish the grunt task to grunt.fail.warn which will require --force to ensure the task does not fail the whole build, you should supply the fail option in the task configuration:

grunt.initConfig({
    remapIstanbul: {
        build: {
            src: 'coverage-final.json',
            options: {
                fail: true
            }
        }
    }
});

Gulp Plugin

You can utilize this package as a gulp plugin. There are two main ways it can be used. Just taking a coverage file, remapping and outputting it would look like this:

var gulp = require('gulp');
var remapIstanbul = require('remap-istanbul/lib/gulpRemapIstanbul');
 
gulp.task('remap-istanbul', function () {
    return gulp.src('coverage-final.json')
        .pipe(remapIstanbul())
        .pipe(gulp.dest('coverage-remapped.json'));
});

Another way is to utilize the plugin is to have the plugin write out the Istanbul reports directly. This can be accomplished by passing a reports property in the options. For example, to have the JSON coverage report output in addition to the HTML coverage report, at task would look like this:

var gulp = require('gulp');
var remapIstanbul = require('remap-istanbul/lib/gulpRemapIstanbul');
 
gulp.task('remap-istanbul', function () {
    return gulp.src('coverage-final.json')
        .pipe(remapIstanbul({
            reports: {
                'json': 'coverage.json',
                'html': 'html-report'
            }
        }));
});

By default, errors in the gulp task will be considered non-fatal and will just be logged to the console. If you wish errors to be emitted and fail the task, you need to supply the task with fail being truthy:

var gulp = require('gulp');
var remapIstanbul = require('remap-istanbul/lib/gulpRemapIstanbul');
 
gulp.task('remap-istanbul', function () {
    return gulp.src('coverage-final.json')
        .pipe(remapIstanbul({
            fail: true
        }));
});

Intern Reporter

The package comes with an Intern reporter that makes it easy to output the coverage.json from a test run. The most common usage from the command line would be something like:

node_modules/.bin/intern-runner config=tests/intern reporters=Console reporters=node_modules/remap-istanbul/lib/intern-reporters/JsonCoverage

This will output a coverage-final.json in the root of your project, which you can use with the rest of remap-istanbul to remap it back to the source files.