src/component/coverage-component.js

'use strict';

/* eslint no-useless-call: 0 */

const DependencyBasedComponent = require('./dependency-based-component');
const istanbul = require('istanbul');
const testEvents = require('./test/events');
const events = require('./coverage/events');
const ContainerTransformer = require('./helper/container-transformer');
const path = require('path');
const fs = require('fs');
const pify = require('pify');
const StorageFactory = require('./coverage/factory');
const ModuleCompile = require('./helper/module-compile');

/**
 * Coverage component
 */
class CoverageComponent extends DependencyBasedComponent {
  /**
   * @param {*} args
   */
  constructor(...args) {
    super(...args);
    
    this._storage = null;
  }
  
  /**
   * @returns {string}
   */
  get name() {
    return 'coverage';
  }
  
  /**
   * @returns {string[]}
   */
  get dependencies() {
    return [ 'test' ];
  }
  
  /**
   * @returns {AbstractDriver}
   *
   * @private
   */
  get _comparatorStorage() {
    if (this._storage) {
      return this._storage;
    }
    
    const driver = this.container.get('compare.storage.driver', 'volatile');
    const options = this.container.get('compare.storage.options', []);
    
    this._storage = StorageFactory.create(driver, ...options);
    
    return this._storage;
  }
  
  /**
   * @param {istanbul.Collector} collector
   *
   * @returns {Promise}
   * 
   * @private
   */
  _doCompare(collector) {
    const allowedDelta = Math.abs(parseFloat(
      this.container.get('compare.negative-delta', 100)
    ));
    
    if (!allowedDelta || allowedDelta >= 100) {
      return Promise.resolve();
    }
    
    const storage = this._comparatorStorage;
    
    if (storage.constructor.name === 'VolatileDriver') {
      this.logger.debug(
        `Coverage stored in ${ storage._storageFile(CoverageComponent.COVERAGE_FILE) }`
      );
    }
    
    return storage.read(CoverageComponent.COVERAGE_FILE)
      .then(coverage => {
        const newCoverage = collector.getFinalCoverage();
        
        if (!coverage) {
          this.logger.info(
            this.logger.emoji.bicycle,
            'No previous coverage info saved...'
          );
          
          return storage.write(
            CoverageComponent.COVERAGE_FILE, 
            newCoverage
          );
        }
        
        const delta = this._calculateDelta(coverage, newCoverage);
        
        if (delta > allowedDelta) {          
          return Promise.reject(new Error(
            `Coverage delta decreased ${ delta.toFixed(2) } > ${ allowedDelta.toFixed(2) }`
          ));
        }
        
        this.logger.info(
          this.logger.emoji.bicycle,
          `Coverage delta checked ${ delta.toFixed(2) } >= ${ allowedDelta.toFixed(2) }`
        );
        
        return storage.write(
          CoverageComponent.COVERAGE_FILE, 
          newCoverage
        );
      });
  }
  
  /**
   * @param {*} coverage
   * @param {*} newCoverage
   *
   * @returns {number}
   *
   * @private
   */
  _calculateDelta(coverage, newCoverage) {
    const summary = this._summarizeCoverage(coverage);
    const newSummary = this._summarizeCoverage(newCoverage);
    
    return CoverageComponent.COVERAGE_KEYS
      .reduce((accumulator, key) => {
        return accumulator + 
          parseFloat(summary[key]) - 
          parseFloat((newSummary[key] || 0));
      }, 0) / CoverageComponent.COVERAGE_KEYS.length;
  }
  
  /**
   * @param {*} coverage
   *
   * @returns {*}
   *
   * @private
   */
  _summarizeCoverage(coverage) {
    const summary = {};
    
    const summaries = Object.keys(coverage)
      .map(file => {
        return istanbul.utils
          .summarizeFileCoverage(coverage[file]);
      });
    
    const summaryObj = istanbul.utils
      .mergeSummaryObjects
      .apply(null, summaries);
    
    Object.keys(summaryObj)
      .map(key => {
        summary[key] = summaryObj[key].pct;
      });
      
    return summary;
  }
  
  /**
   * @param {*} assetsToInstrument
   * @param {*} dispatchedAssets
   * @param {EmitModule} module
   *
   * @returns {Promise}
   * 
   * @private
   */
  _persistModuleBlankCoverage(assetsToInstrument, dispatchedAssets, module) {
    if (!assetsToInstrument[module.name]) {
      return Promise.resolve();
    }
    
    const coverageVariable = this._coverageVariable(module);
    
    return Promise.all(
      assetsToInstrument[module.name]
        .filter(asset => {
          return (dispatchedAssets[module.name] || []).indexOf(asset) === -1;
        })
        .map(asset => {
          return pify(fs.readFile)(asset)
            .then(content => {
              const instrumenter = new istanbul.Instrumenter({ coverageVariable });

              instrumenter.instrumentSync(
                content.toString(), 
                asset
              );
              
              global[coverageVariable] = global[coverageVariable] || {};
              global[coverageVariable][asset] = instrumenter.lastFileCoverage();

              return Promise.resolve();  
            });
        })
    );
  }
  
  /**
   * @param {Emitter} emitter
   * @returns {Promise}
   * @todo split into several abstractions
   */
  run(emitter) {
    return new Promise((resolve, reject) => {
      const collector = new istanbul.Collector();
      const reporter = new istanbul.Reporter();
      const reporters = this.container.get('reporters', {});
      const coverageVariables = [];
      const assetsToInstrument = {};
      const dispatchedAssets = {};
      
      Object.keys(reporters).map(reporterName => {
        reporter.reports[reporterName] = istanbul.Report.create(reporterName, reporters[reporterName] || {});
      });
      
      emitter.onBlocking(testEvents.asset.test.skip, payload => {
        if (!this._match(payload.file)) {
          return Promise.resolve();
        }
        
        const { module, fileAbs } = payload;
        
        assetsToInstrument[module.name] = assetsToInstrument[module.name] || [];
        assetsToInstrument[module.name].push(fileAbs);
        
        return Promise.resolve();
      });
      
      emitter.onBlocking(testEvents.asset.tests.end, (mocha, module) => {
        return this._persistModuleBlankCoverage(assetsToInstrument, dispatchedAssets, module).then(() => {
          delete assetsToInstrument[module.name];
          delete dispatchedAssets[module.name];
          
          return Promise.resolve();
        });
      });
      
      emitter.onBlocking(testEvents.asset.tests.start, (mocha, module) => {
        return new Promise(resolve => {
          const instrumenterCache = {};
          const coverageVariable = this._coverageVariable(module);
          const instrumenter = new istanbul.Instrumenter({ coverageVariable });
          
          coverageVariables.push(coverageVariable);
          
          if (mocha) {
            mocha.loadFiles = (fn => {
              const self = this;
              const moduleRoot = module.container.get('root');
              const coverableAssets = assetsToInstrument[module.name] || [];

              const preprocessor = (source, filename) => {
                if (coverableAssets.indexOf(filename) !== -1
                  && self._match(path.relative(moduleRoot, filename))) {

                  if (instrumenterCache.hasOwnProperty(filename)) {
                    return instrumenterCache[filename];
                  }
                  
                  instrumenterCache[filename] = instrumenter.instrumentSync.call(instrumenter, source, filename);
                  dispatchedAssets[module.name] = dispatchedAssets[module.name] || [];
                  dispatchedAssets[module.name].push(filename);
                  
                  return instrumenterCache[filename];
                }
                
                return source;
              };
              
              mocha.files.map(file => {
                file = path.resolve(file);
                
                mocha.suite.emit('pre-require', global, file, mocha);
                mocha.suite.emit('require', ModuleCompile.require(file, {}, preprocessor), file, mocha);
                mocha.suite.emit('post-require', global, file, mocha);
              });
              
              fn && fn();
            });
          }
          
          resolve();
        });
      });
      
      emitter.onBlocking(testEvents.assets.test.end, () => {        
        coverageVariables.map(coverageVariable => {
          collector.add(global[coverageVariable] || {});
        });
        
        return emitter.emitBlocking(events.coverage.report.create, istanbul, reporter, collector)
          .then(() => this._dumpCoverageStats(collector, reporter))
          .then(() => emitter.emitBlocking(events.coverage.report.compare, istanbul, reporter, collector))
          .then(() => this._doCompare(collector));
      });
      
      emitter.on(testEvents.assets.test.end, () => resolve());
    });
  }
  
  /**
   * @param {istanbul.Collector} collector
   * @param {istanbul.Reporter} reporter
   *
   * @returns {Promise}
   * 
   * @private
   */
  _dumpCoverageStats(collector, reporter) {
    return new Promise(resolve => {
      reporter.write(collector, false, () => {
        
        // @todo find a smarter way to indent the output (buffer it?)
        process.stdout.write('\n\n');
        
        resolve();
      });
    });
  }
  
  /**
   * @param {EmitModule} module
   *
   * @returns {string}
   *
   * @private
   */
  _coverageVariable(module) {
    const cleanModuleName = module.name.replace(/[^a-z0-9]/g, '_');
    
    return `__recink_coverage__${ cleanModuleName }__`;
  }
  
  /**
   * @param {string} file
   *
   * @returns {boolean}
   * 
   * @private
   */
  _match(file) {
    const pattern = this.container.get('pattern', []);
    const ignore = this.container.get('ignore', []);

    const result = pattern.filter(p => this._test(p, file)).length > 0
      && ignore.filter(i => this._test(i, file)).length <= 0;
      
    return result;
  }
  
  /**
   * @param {string|RegExp} pattern
   * @param {string} value
   *
   * @returns {boolean}
   *
   * @private
   */
  _test(pattern, value) {
    if (!(pattern instanceof RegExp)) {
      return value.indexOf(pattern.toString()) !== -1;
    }
    
    return pattern.test(value);
  }
  
  /**
   * @param {*} config
   * @param {string} configFile
   *
   * @returns {Container}
   */
  prepareConfig(config, configFile) {
    return super.prepareConfig(config, configFile)
      .then(container => {
        return (new ContainerTransformer(container))
          .addPattern('pattern')
          .addPattern('ignore')
          .transform();
      });
  }
  
  /**
   * @returns {Array}
   */
  static get COVERAGE_KEYS() {
    return [ 'lines', 'statements', 'functions', 'branches' ];
  }
  
  /**
   * @returns {string}
   */
  static get COVERAGE_FILE() {
    return 'coverage.json';
  }
}

module.exports = CoverageComponent;