Full Gulp Istanbul Coverage Report

Question

I am using gulp-istanbul to generate JavaScript unit test coverage reports through Gulp. Is there a way to configure Istanbul to generate a full coverage report of all the JS files in my gulp stream, and not just the files touched by a test case.

I'm working on a project with a lot of JS, but no unit tests, and we are trying to increase the test coverage. I would like to have a coverage report that starts by show 0% coverage for most of our files, but over time will present an increasing coverage percentage.

gulp.task( 'test', function () {
    gulp.src( [ my source glob ] )
        .pipe( istanbul() )
        .on( 'end', function () {
            gulp.src( [ my test spec glob ] )
                .pipe( mocha( {
                    reporter: 'spec'
                } ) )
                .pipe( istanbul.writeReports(
                    [ output location ]
                ) );
        } );
} );

Answer 1

It actually is much more simple now and you just have to add includeUntested to your istanbul() call.

gulp.task('test', function () {
    return gulp.src('./assets/**/js/*.js')
      // Right there
      .pipe(istanbul({includeUntested: true}))
      .on('finish', function () {
        gulp.src('./assets/js/test/test.js')
          .pipe(mocha({reporter: 'spec'}))
          .pipe(istanbul.writeReports({
            dir: './assets/unit-test-coverage',
            reporters: [ 'lcov' ],
            reportOpts: { dir: './assets/unit-test-coverage'}
          }));
      });
  });

Source : https://github.com/SBoudrias/gulp-istanbul#includeuntested

Answer 2

Istanbul hook is executed when the file is required. So, you need to require all files in order for them to be included in the final coverage report. You can achieve this by injecting a tap inside your gulp task and call require on all selected files:

gulp.task( 'test', function () {
    gulp.src( [ my source glob ] )
        .pipe( istanbul() )
        .pipe(tap(function(f) {
            // Make sure all files are loaded to get accurate coverage data
            require(f.path);
        }))
        .on( 'end', function () {
            gulp.src( [ my test spec glob ] )
                .pipe( mocha( {
                    reporter: 'spec'
                } ) )
                .pipe( istanbul.writeReports(
                    [ output location ]
                ) );
        } );
} );