gecko-dev/testing/modules/CoverageUtils.jsm

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

var EXPORTED_SYMBOLS = ["CoverageCollector"];

/* globals Debugger */
const { addDebuggerToGlobal } = ChromeUtils.import(
  "resource://gre/modules/jsdebugger.jsm"
);
// eslint-disable-next-line mozilla/reject-globalThis-modification
addDebuggerToGlobal(globalThis);

/**
 * Records coverage for each test by way of the js debugger.
 */
var CoverageCollector = function(prefix) {
  this._prefix = prefix;
  this._dbg = new Debugger();
  this._dbg.collectCoverageInfo = true;
  this._dbg.addAllGlobalsAsDebuggees();
  this._scripts = this._dbg.findScripts();

  this._dbg.onNewScript = script => {
    this._scripts.push(script);
  };

  // Source -> coverage data;
  this._allCoverage = {};
  this._encoder = new TextEncoder();

  this._testIndex = 0;
};

CoverageCollector.prototype._getLinesCovered = function() {
  let coveredLines = {};
  let currentCoverage = {};
  this._scripts.forEach(s => {
    let scriptName = s.url;
    let cov = s.getOffsetsCoverage();
    if (!cov) {
      return;
    }

    cov.forEach(covered => {
      let { lineNumber, columnNumber, offset, count } = covered;
      if (!count) {
        return;
      }

      if (!currentCoverage[scriptName]) {
        currentCoverage[scriptName] = {};
      }
      if (!this._allCoverage[scriptName]) {
        this._allCoverage[scriptName] = {};
      }

      let key = [lineNumber, columnNumber, offset].join("#");
      if (!currentCoverage[scriptName][key]) {
        currentCoverage[scriptName][key] = count;
      } else {
        currentCoverage[scriptName][key] += count;
      }
    });
  });

  // Covered lines are determined by comparing every offset mentioned as of the
  // the completion of a test to the last time we measured coverage. If an
  // offset in a line is novel as of this test, or a count has increased for
  // any offset on a particular line, that line must have been covered.
  for (let scriptName in currentCoverage) {
    for (let key in currentCoverage[scriptName]) {
      if (
        !this._allCoverage[scriptName] ||
        !this._allCoverage[scriptName][key] ||
        this._allCoverage[scriptName][key] < currentCoverage[scriptName][key]
      ) {
        // eslint-disable-next-line no-unused-vars
        let [lineNumber, colNumber, offset] = key.split("#");
        if (!coveredLines[scriptName]) {
          coveredLines[scriptName] = new Set();
        }
        coveredLines[scriptName].add(parseInt(lineNumber, 10));
        this._allCoverage[scriptName][key] = currentCoverage[scriptName][key];
      }
    }
  }

  return coveredLines;
};

CoverageCollector.prototype._getUncoveredLines = function() {
  let uncoveredLines = {};
  this._scripts.forEach(s => {
    let scriptName = s.url;
    let scriptOffsets = s.getAllOffsets();

    if (!uncoveredLines[scriptName]) {
      uncoveredLines[scriptName] = new Set();
    }

    // Get all lines in the script
    scriptOffsets.forEach(function(element, index) {
      if (!element) {
        return;
      }
      uncoveredLines[scriptName].add(index);
    });
  });

  // For all covered lines, delete their entry
  for (let scriptName in this._allCoverage) {
    for (let key in this._allCoverage[scriptName]) {
      // eslint-disable-next-line no-unused-vars
      let [lineNumber, columnNumber, offset] = key.split("#");
      uncoveredLines[scriptName].delete(parseInt(lineNumber, 10));
    }
  }

  return uncoveredLines;
};

CoverageCollector.prototype._getMethodNames = function() {
  let methodNames = {};
  this._scripts.forEach(s => {
    let method = s.displayName;
    // If the method name is undefined, we return early
    if (!method) {
      return;
    }

    let scriptName = s.url;
    let tempMethodCov = [];
    let scriptOffsets = s.getAllOffsets();

    if (!methodNames[scriptName]) {
      methodNames[scriptName] = {};
    }

    /**
     * Get all lines contained within the method and
     * push a record of the form:
     * <method name> : <lines covered>
     */
    scriptOffsets.forEach(function(element, index) {
      if (!element) {
        return;
      }
      tempMethodCov.push(index);
    });
    methodNames[scriptName][method] = tempMethodCov;
  });

  return methodNames;
};

/**
 * Records lines covered since the last time coverage was recorded,
 * associating them with the given test name. The result is written
 * to a json file in a specified directory.
 */
CoverageCollector.prototype.recordTestCoverage = function(testName) {
  const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");

  dump("Collecting coverage for: " + testName + "\n");
  let rawLines = this._getLinesCovered(testName);
  let methods = this._getMethodNames();
  let uncoveredLines = this._getUncoveredLines();
  let result = [];
  let versionControlBlock = { version: 1.0 };
  result.push(versionControlBlock);

  for (let scriptName in rawLines) {
    let rec = {
      testUrl: testName,
      sourceFile: scriptName,
      methods: {},
      covered: [],
      uncovered: [],
    };

    if (
      typeof methods[scriptName] != "undefined" &&
      methods[scriptName] != null
    ) {
      for (let [methodName, methodLines] of Object.entries(
        methods[scriptName]
      )) {
        rec.methods[methodName] = methodLines;
      }
    }

    for (let line of rawLines[scriptName]) {
      rec.covered.push(line);
    }

    for (let line of uncoveredLines[scriptName]) {
      rec.uncovered.push(line);
    }

    result.push(rec);
  }
  let arr = this._encoder.encode(JSON.stringify(result, null, 2));
  let path = this._prefix + "/jscov_" + Date.now() + ".json";
  dump("Writing coverage to: " + path + "\n");
  return OS.File.writeAtomic(path, arr, { tmpPath: path + ".tmp" });
};

/**
 * Tear down the debugger after all tests are complete.
 */
CoverageCollector.prototype.finalize = function() {
  this._dbg.removeAllDebuggees();
  this._dbg.enabled = false;
};