infra-sk/karma_mocha_test/karma.conf.js - buildbot - Git at Google

 // Karma configuration
 // GENERATED BY Bazel
 try {
   const fs = require('fs');
   const path = require('path');
   const tmp = require('tmp');
   const child_process = require('child_process');
   const runfiles = require(process.env['BAZEL_NODE_RUNFILES_HELPER']);

   const VERBOSE_LOGS = !!process.env['VERBOSE_LOGS'];

   function log_verbose(...m) {
     // This is a template file so we use __filename to output the actual filename
     if (VERBOSE_LOGS) console.error(`[${path.basename(__filename)}]`, ...m);
   }

   // BEGIN ENV VARS
   TMPL_env_vars
   // END ENV VARS

   const configPath = 'TMPL_config_file';

   log_verbose(`running with
     cwd: ${process.cwd()}
     configPath: ${configPath}`);

   /**
    * Helper function to find a particular namedFile
    * within the webTestMetadata webTestFiles
    */
   function findNamedFile(webTestMetadata, key) {
     let result;
     webTestMetadata['webTestFiles'].forEach(entry => {
       const webTestNamedFiles = entry['namedFiles'];
       if (webTestNamedFiles && webTestNamedFiles[key]) {
         result = webTestNamedFiles[key];
       }
     });
     return result;
   }

   /**
    * Helper function to extract a browser archive
    * and return the path to extract executable
    */
   function extractWebArchive(extractExe, archiveFile, executablePath) {
     try {
       // Paths are relative to the root runfiles folder
       extractExe = extractExe ? path.join('..', extractExe) : extractExe;
       archiveFile = path.join('..', archiveFile);
       const extractedExecutablePath = path.join(process.cwd(), executablePath);
       if (!extractExe) {
         throw new Error('No EXTRACT_EXE found');
       }
       child_process.execFileSync(
           extractExe, [archiveFile, '.'], {stdio: [process.stdin, process.stdout, process.stderr]});
       log_verbose(
           `Extracting web archive ${archiveFile} with ${extractExe} to ${extractedExecutablePath}`);
       return extractedExecutablePath;
     } catch (e) {
       console.error(`Failed to extract ${archiveFile}`);
       throw e;
     }
   }

   /**
    * Check if Chrome sandboxing is supported on the current platform.
    */
   function supportChromeSandboxing() {
     if (process.platform === 'darwin') {
       // Chrome 73+ fails to initialize the sandbox on OSX when running under Bazel.
       // ```
       // ERROR [launcher]: Cannot start ChromeHeadless
       // ERROR:crash_report_database_mac.mm(96)] mkdir
       // /private/var/tmp/_bazel_greg/62ef096b0da251c6d093468a1efbfbd3/execroot/angular/bazel-out/darwin-fastbuild/bin/external/io_bazel_rules_webtesting/third_party/chromium/chromium.out/chrome-mac/Chromium.app/Contents/Versions/73.0.3683.0/Chromium
       // Framework.framework/Versions/A/new: Permission denied (13) ERROR:file_io.cc(89)]
       // ReadExactly: expected 8, observed 0 ERROR:crash_report_database_mac.mm(96)] mkdir
       // /private/var/tmp/_bazel_greg/62ef096b0da251c6d093468a1efbfbd3/execroot/angular/bazel-out/darwin-fastbuild/bin/external/io_bazel_rules_webtesting/third_party/chromium/chromium.out/chrome-mac/Chromium.app/Contents/Versions/73.0.3683.0/Chromium
       // Framework.framework/Versions/A/new: Permission denied (13) Chromium Helper[94642] <Error>:
       // SeatbeltExecServer: Failed to initialize sandbox: -1 Operation not permitted Failed to
       // initialize sandbox. [0213/201206.137114:FATAL:content_main_delegate.cc(54)] Check failed:
       // false. 0   Chromium Framework                  0x000000010c078bc9 ChromeMain + 43788137 1
       // Chromium Framework                  0x000000010bfc0f43 ChromeMain + 43035363
       // ...
       // ```
       return false;
     }

     if (process.platform === 'linux') {
       // Chrome on Linux uses sandboxing, which needs user namespaces to be enabled.
       // This is not available on all kernels and it might be turned off even if it is available.
       // Notable examples where user namespaces are not available include:
       // - In Debian it is compiled-in but disabled by default.
       // - The Docker daemon for Windows or OSX does not support user namespaces.
       // We can detect if user namespaces are supported via
       // /proc/sys/kernel/unprivileged_userns_clone. For more information see:
       // https://github.com/Googlechrome/puppeteer/issues/290
       // https://superuser.com/questions/1094597/enable-user-namespaces-in-debian-kernel#1122977
       // https://github.com/karma-runner/karma-chrome-launcher/issues/158
       // https://github.com/angular/angular/pull/24906
       try {
         const res = child_process.execSync('cat /proc/sys/kernel/unprivileged_userns_clone')
                         .toString()
                         .trim();
         return res === '1';
       } catch (error) {
       }
       return false;
     }

     return true;
   }

   /**
    * Helper function to override base karma config values.
    */
   function overrideConfigValue(conf, name, value) {
     if (conf.hasOwnProperty(name)) {
       console.warn(
           `Your karma configuration specifies '${name}' which will be overwritten by Bazel`);
     }
     conf[name] = value;
   }

   /**
    * Helper function to merge base karma config values that are arrays.
    */
   function mergeConfigArray(conf, name, values) {
     if (!conf[name]) {
       conf[name] = [];
     }
     values.forEach(v => {
       if (!conf[name].includes(v)) {
         conf[name].push(v);
       }
     })
   }

   /**
    * Configuration settings for karma under Bazel common to karma_web_test
    * and karma_web_test_suite.
    */
   function configureBazelConfig(config, conf) {
     // list of karma plugins
     mergeConfigArray(conf, 'plugins', [
       // Loads 'concat_js'
       require('@bazel/karma'),
       // Load plugins that are peer deps. These packages are used in this config file.
       require('karma-chrome-launcher'),
       require('karma-firefox-launcher'),
       require('karma-mocha'),
       require('karma-requirejs'),
       require('karma-sourcemap-loader'),
       // Loads user-installed karma-* packages in the root node_modules.
       'karma-*',
     ]);

     // list of karma preprocessors
     if (!conf.preprocessors) {
       conf.preprocessors = {}
     }
     conf.preprocessors['**/*.js'] = ['sourcemap'];

     // list of test frameworks to use
     overrideConfigValue(conf, 'frameworks', ['mocha', 'concat_js']);

     // test results reporter to use
     // possible values: 'dots', 'progress'
     // available reporters: https://npmjs.org/browse/keyword/karma-reporter
     mergeConfigArray(conf, 'reporters', ['progress']);

     // enable / disable colors in the output (reporters and logs)
     if (!conf.colors) {
       conf.colors = true;
     }

     // level of logging
     // possible values: config.LOG_DISABLE || config.LOG_ERROR ||
     // config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
     conf.logLevel = VERBOSE_LOGS ? config.LOG_DEBUG : config.LOG_INFO;

     // enable / disable watching file and executing tests whenever
     // any file changes
     overrideConfigValue(conf, 'autoWatch', process.env['IBAZEL_NOTIFY_CHANGES'] === 'y');

     // Continuous Integration mode
     // if true, Karma captures browsers, runs the tests and exits
     // note: run_karma.sh may override this as a command-line option.
     overrideConfigValue(conf, 'singleRun', false);

     // Concurrency level
     // how many browser should be started simultaneous
     overrideConfigValue(conf, 'concurrency', Infinity);

     // base path that will be used to resolve all patterns
     // (eg. files, exclude)
     overrideConfigValue(conf, 'basePath', 'TMPL_runfiles_path');

     // Do not show "no timestamp" errors from "karma-requirejs" for proxied file
     // requests. Files which are passed as "static_files" are proxied by default and
     // therefore should not cause such an exception when loaded as expected.
     // See: https://github.com/karma-runner/karma-requirejs/issues/6
     const requireJsShowNoTimestampsError = '^(?!/base/).*$';

     if (conf.client) {
       overrideConfigValue(
           conf.client, 'requireJsShowNoTimestampsError', requireJsShowNoTimestampsError);
     } else {
       conf.client = {requireJsShowNoTimestampsError};
     }
   }

   /**
    * Configure the 'files' and 'proxies' configuration attributes.
    * These are concatenated into a single file by karma-concat-js.
    */
   function configureFiles(conf) {
     overrideConfigValue(conf, 'files', []);
     overrideConfigValue(conf, 'exclude', []);
     overrideConfigValue(conf, 'proxies', {});

     // Static files are added to the files array but configured to not be included,
     // so karma-concat-js does not included them in the bundle. Note that we need
     // to add the static files before adding the included files as we don't want
     // to overwrite included files (changing from included to not included).
     [
         // BEGIN STATIC FILES
         TMPL_static_files
         // END STATIC FILES
     ].forEach((f) => {
       // In Windows, the runfile will probably not be symlinked. Se we need to
       // serve the real file through karma, and proxy calls to the expected file
       // location in the runfiles to the real file.
       const resolvedFile = runfiles.resolve(f);
       conf.files.push({pattern: resolvedFile, included: false});
       // Prefixing the proxy path with '/absolute' allows karma to load local
       // files. This doesn't see to be an official API.
       // https://github.com/karma-runner/karma/issues/2703
       conf.proxies['/base/' + f] = '/absolute' + resolvedFile;
     });

     [
       // BEGIN BOOTSTRAP FILES
       TMPL_bootstrap_files
     // END BOOTSTRAP FILES
     // BEGIN USER FILES
       TMPL_user_files
       // END USER FILES
     ].forEach(f => conf.files.push(runfiles.resolve(f)))

       var requireConfigContent = `
       // A simplified version of Karma's requirejs.config.tpl.js for use with Karma under Bazel.
       // This does an explicit \`require\` on each test script in the files, otherwise nothing will be loaded.
       (function(){
         var runtimeFiles = [
           // BEGIN RUNTIME FILES
           TMPL_runtime_files
           // END RUNTIME FILES
         ].map(function(file) { return file.replace(/\\.js$/, ''); });
         var allFiles = [
             // BEGIN USER FILES
             TMPL_user_files
             // END USER FILES
         ];
         var allTestFiles = [];
         allFiles.forEach(function (file) {
           if (/[^a-zA-Z0-9](spec|test)\\.js$/i.test(file) && !/\\/node_modules\\//.test(file)) {
             allTestFiles.push(file.replace(/\\.js$/, ''))
           }
         });
         require(runtimeFiles, function() { return require(allTestFiles, window.__karma__.start); });
       })();
     `;

       const requireConfigFile =
           tmp.fileSync({keep: false, postfix: '.js', dir: process.env['TEST_TMPDIR']});
       fs.writeFileSync(requireConfigFile.name, requireConfigContent);
       conf.files.push(requireConfigFile.name);
   }

   /**
    * Configure karma under karma_web_test_suite.
    * `browsers` and `customLaunchers` are setup by Bazel.
    */
   function configureTsWebTestSuiteConfig(conf) {
     // WEB_TEST_METADATA is configured in rules_webtesting based on value
     // of the browsers attribute passed to karms_web_test_suite
     // We setup the karma configuration based on the values in this object
     if (!process.env['WEB_TEST_METADATA']) {
       // This is a karma_web_test rule since there is no WEB_TEST_METADATA
       return;
     }

     overrideConfigValue(conf, 'browsers', []);
     overrideConfigValue(conf, 'customLaunchers', null);

     const webTestMetadata = require(runfiles.resolve(process.env['WEB_TEST_METADATA']));
     log_verbose(`WEB_TEST_METADATA: ${JSON.stringify(webTestMetadata, null, 2)}`);
     if (webTestMetadata['environment'] === 'local') {
       // When a local chrome or firefox browser is chosen such as
       // "@io_bazel_rules_webtesting//browsers:chromium-local" or
       // "@io_bazel_rules_webtesting//browsers:firefox-local"
       // then the 'environment' will equal 'local' and
       // 'webTestFiles' will contain the path to the binary to use
       const extractExe = findNamedFile(webTestMetadata, 'EXTRACT_EXE');
       webTestMetadata['webTestFiles'].forEach(webTestFiles => {
         const webTestNamedFiles = webTestFiles['namedFiles'];
         const archiveFile = webTestFiles['archiveFile'];
         if (webTestNamedFiles['CHROMIUM']) {
           // When karma is configured to use Chrome it will look for a CHROME_BIN
           // environment variable.
           if (archiveFile) {
             process.env.CHROME_BIN =
                 extractWebArchive(extractExe, archiveFile, webTestNamedFiles['CHROMIUM']);
           } else {
             try {
               process.env.CHROME_BIN = runfiles.resolve(webTestNamedFiles['CHROMIUM']);
             } catch {
               // Fail as this file is expected to be in runfiles
               throw new Error(`Failed to resolve rules_webtesting Chromium binary '${
                   webTestNamedFiles['CHROMIUM']}' in runfiles`);
             }
           }
           const browser = process.env['DISPLAY'] ? 'Chrome' : 'ChromeHeadless';
           if (!supportChromeSandboxing()) {
             const launcher = 'CustomChromeWithoutSandbox';
             conf.customLaunchers = {[launcher]: {base: browser, flags: ['--no-sandbox']}};
             conf.browsers.push(launcher);
           } else {
             conf.browsers.push(browser);
           }
         }
         if (webTestNamedFiles['FIREFOX']) {
           // When karma is configured to use Firefox it will look for a
           // FIREFOX_BIN environment variable.
           if (archiveFile) {
             process.env.FIREFOX_BIN =
                 extractWebArchive(extractExe, archiveFile, webTestNamedFiles['FIREFOX']);
           } else {
             try {
               process.env.FIREFOX_BIN = runfiles.resolve(webTestNamedFiles['FIREFOX']);
             } catch {
               // Fail as this file is expected to be in runfiles
               throw new Error(`Failed to resolve rules_webtesting Firefox binary '${
                   webTestNamedFiles['FIREFOX']}' in runfiles`);
             }
           }
           conf.browsers.push(process.env['DISPLAY'] ? 'Firefox' : 'FirefoxHeadless');
         }
       });
     } else {
       throw new Error(`Unknown WEB_TEST_METADATA environment '${webTestMetadata['environment']}'`);
     }

     if (!conf.browsers.length) {
       throw new Error('No browsers configured in web test suite');
     }
   }

   function configureTsWebTestConfig(conf) {
     if (process.env['WEB_TEST_METADATA']) {
       // This is a karma_web_test_suite rule since there is a WEB_TEST_METADATA
       return;
     }

     // Fallback to using the system local chrome if no valid browsers have been
     // configured above
     if (!conf.browsers || !conf.browsers.length) {
       console.warn('No browsers configured. Configuring Karma to use system Chrome.');
       conf.browsers = [process.env['DISPLAY'] ? 'Chrome' : 'ChromeHeadless'];
     }
   }

   function configureFormatError(conf) {
     conf.formatError = (msg) => {
       // This is a bazel specific formatError that removes the workspace
       // name from stack traces.
       // Look for filenames of the format "(<filename>:<row>:<column>"
       const FILENAME_REGEX = /\(([^:\n\r]+)(:\d+:\d+)/gm;
       msg = msg.replace(FILENAME_REGEX, (_, p1, p2) => {
         if (p1.startsWith('../')) {
           // Remove all leading "../"
           while (p1.startsWith('../')) {
             p1 = p1.substr(3);
           }
         } else {
           // Remove workspace name(angular, ngdeps etc.) from the beginning.
           const index = p1.indexOf('/');
           if (index >= 0) {
             p1 = p1.substr(index + 1);
           }
         }
         return '(' + p1 + p2;
       });
       return msg + '\n\n';
     };
   }

   module.exports = function(config) {
     let conf = {};

     // Import the user's base karma configuration if specified
     if (configPath) {
       const baseConf = require(runfiles.resolve(configPath));
       if (typeof baseConf !== 'function') {
         throw new Error(
             'Invalid base karma configuration. Expected config function to be exported.');
       }
       const originalSetConfig = config.set;
       config.set = function(c) {
         conf = c;
       };
       baseConf(config);
       config.set = originalSetConfig;
       log_verbose(`base karma configuration: ${JSON.stringify(conf, null, 2)}`);
     }

     configureBazelConfig(config, conf);
     configureFiles(conf);
     configureTsWebTestSuiteConfig(conf);
     configureTsWebTestConfig(conf);
     configureFormatError(conf);

     log_verbose(`karma configuration: ${JSON.stringify(conf, null, 2)}`);

     config.set(conf);
   }
 } catch (e) {
   console.error('Error in karma configuration', e.toString());
   throw e;
 }
	// Karma configuration
	// GENERATED BY Bazel
	try {
	const fs = require('fs');
	const path = require('path');
	const tmp = require('tmp');
	const child_process = require('child_process');
	const runfiles = require(process.env['BAZEL_NODE_RUNFILES_HELPER']);

	const VERBOSE_LOGS = !!process.env['VERBOSE_LOGS'];

	function log_verbose(...m) {
	// This is a template file so we use __filename to output the actual filename
	if (VERBOSE_LOGS) console.error(`[${path.basename(__filename)}]`, ...m);
	}

	// BEGIN ENV VARS
	TMPL_env_vars
	// END ENV VARS

	const configPath = 'TMPL_config_file';

	log_verbose(`running with
	cwd: ${process.cwd()}
	configPath: ${configPath}`);

	/**
	* Helper function to find a particular namedFile
	* within the webTestMetadata webTestFiles
	*/
	function findNamedFile(webTestMetadata, key) {
	let result;
	webTestMetadata['webTestFiles'].forEach(entry => {
	const webTestNamedFiles = entry['namedFiles'];
	if (webTestNamedFiles && webTestNamedFiles[key]) {
	result = webTestNamedFiles[key];
	}
	});
	return result;
	}

	/**
	* Helper function to extract a browser archive
	* and return the path to extract executable
	*/
	function extractWebArchive(extractExe, archiveFile, executablePath) {
	try {
	// Paths are relative to the root runfiles folder
	extractExe = extractExe ? path.join('..', extractExe) : extractExe;
	archiveFile = path.join('..', archiveFile);
	const extractedExecutablePath = path.join(process.cwd(), executablePath);
	if (!extractExe) {
	throw new Error('No EXTRACT_EXE found');
	}
	child_process.execFileSync(
	extractExe, [archiveFile, '.'], {stdio: [process.stdin, process.stdout, process.stderr]});
	log_verbose(
	`Extracting web archive ${archiveFile} with ${extractExe} to ${extractedExecutablePath}`);
	return extractedExecutablePath;
	} catch (e) {
	console.error(`Failed to extract ${archiveFile}`);
	throw e;
	}
	}

	/**
	* Check if Chrome sandboxing is supported on the current platform.
	*/
	function supportChromeSandboxing() {
	if (process.platform === 'darwin') {
	// Chrome 73+ fails to initialize the sandbox on OSX when running under Bazel.
	// ```
	// ERROR [launcher]: Cannot start ChromeHeadless
	// ERROR:crash_report_database_mac.mm(96)] mkdir
	// /private/var/tmp/_bazel_greg/62ef096b0da251c6d093468a1efbfbd3/execroot/angular/bazel-out/darwin-fastbuild/bin/external/io_bazel_rules_webtesting/third_party/chromium/chromium.out/chrome-mac/Chromium.app/Contents/Versions/73.0.3683.0/Chromium
	// Framework.framework/Versions/A/new: Permission denied (13) ERROR:file_io.cc(89)]
	// ReadExactly: expected 8, observed 0 ERROR:crash_report_database_mac.mm(96)] mkdir
	// /private/var/tmp/_bazel_greg/62ef096b0da251c6d093468a1efbfbd3/execroot/angular/bazel-out/darwin-fastbuild/bin/external/io_bazel_rules_webtesting/third_party/chromium/chromium.out/chrome-mac/Chromium.app/Contents/Versions/73.0.3683.0/Chromium
	// Framework.framework/Versions/A/new: Permission denied (13) Chromium Helper[94642] <Error>:
	// SeatbeltExecServer: Failed to initialize sandbox: -1 Operation not permitted Failed to
	// initialize sandbox. [0213/201206.137114:FATAL:content_main_delegate.cc(54)] Check failed:
	// false. 0 Chromium Framework 0x000000010c078bc9 ChromeMain + 43788137 1
	// Chromium Framework 0x000000010bfc0f43 ChromeMain + 43035363
	// ...
	// ```
	return false;
	}

	if (process.platform === 'linux') {
	// Chrome on Linux uses sandboxing, which needs user namespaces to be enabled.
	// This is not available on all kernels and it might be turned off even if it is available.
	// Notable examples where user namespaces are not available include:
	// - In Debian it is compiled-in but disabled by default.
	// - The Docker daemon for Windows or OSX does not support user namespaces.
	// We can detect if user namespaces are supported via
	// /proc/sys/kernel/unprivileged_userns_clone. For more information see:
	// https://github.com/Googlechrome/puppeteer/issues/290
	// https://superuser.com/questions/1094597/enable-user-namespaces-in-debian-kernel#1122977
	// https://github.com/karma-runner/karma-chrome-launcher/issues/158
	// https://github.com/angular/angular/pull/24906
	try {
	const res = child_process.execSync('cat /proc/sys/kernel/unprivileged_userns_clone')
	.toString()
	.trim();
	return res === '1';
	} catch (error) {
	}
	return false;
	}

	return true;
	}

	/**
	* Helper function to override base karma config values.
	*/
	function overrideConfigValue(conf, name, value) {
	if (conf.hasOwnProperty(name)) {
	console.warn(
	`Your karma configuration specifies '${name}' which will be overwritten by Bazel`);
	}
	conf[name] = value;
	}

	/**
	* Helper function to merge base karma config values that are arrays.
	*/
	function mergeConfigArray(conf, name, values) {
	if (!conf[name]) {
	conf[name] = [];
	}
	values.forEach(v => {
	if (!conf[name].includes(v)) {
	conf[name].push(v);
	}
	})
	}

	/**
	* Configuration settings for karma under Bazel common to karma_web_test
	* and karma_web_test_suite.
	*/
	function configureBazelConfig(config, conf) {
	// list of karma plugins
	mergeConfigArray(conf, 'plugins', [
	// Loads 'concat_js'
	require('@bazel/karma'),
	// Load plugins that are peer deps. These packages are used in this config file.
	require('karma-chrome-launcher'),
	require('karma-firefox-launcher'),
	require('karma-mocha'),
	require('karma-requirejs'),
	require('karma-sourcemap-loader'),
	// Loads user-installed karma-* packages in the root node_modules.
	'karma-*',
	]);

	// list of karma preprocessors
	if (!conf.preprocessors) {
	conf.preprocessors = {}
	}
	conf.preprocessors['*/.js'] = ['sourcemap'];

	// list of test frameworks to use
	overrideConfigValue(conf, 'frameworks', ['mocha', 'concat_js']);

	// test results reporter to use
	// possible values: 'dots', 'progress'
	// available reporters: https://npmjs.org/browse/keyword/karma-reporter
	mergeConfigArray(conf, 'reporters', ['progress']);

	// enable / disable colors in the output (reporters and logs)
	if (!conf.colors) {
	conf.colors = true;
	}

	// level of logging
	// possible values: config.LOG_DISABLE \|\| config.LOG_ERROR \|\|
	// config.LOG_WARN \|\| config.LOG_INFO \|\| config.LOG_DEBUG
	conf.logLevel = VERBOSE_LOGS ? config.LOG_DEBUG : config.LOG_INFO;

	// enable / disable watching file and executing tests whenever
	// any file changes
	overrideConfigValue(conf, 'autoWatch', process.env['IBAZEL_NOTIFY_CHANGES'] === 'y');

	// Continuous Integration mode
	// if true, Karma captures browsers, runs the tests and exits
	// note: run_karma.sh may override this as a command-line option.
	overrideConfigValue(conf, 'singleRun', false);

	// Concurrency level
	// how many browser should be started simultaneous
	overrideConfigValue(conf, 'concurrency', Infinity);

	// base path that will be used to resolve all patterns
	// (eg. files, exclude)
	overrideConfigValue(conf, 'basePath', 'TMPL_runfiles_path');

	// Do not show "no timestamp" errors from "karma-requirejs" for proxied file
	// requests. Files which are passed as "static_files" are proxied by default and
	// therefore should not cause such an exception when loaded as expected.
	// See: https://github.com/karma-runner/karma-requirejs/issues/6
	const requireJsShowNoTimestampsError = '^(?!/base/).*$';

	if (conf.client) {
	overrideConfigValue(
	conf.client, 'requireJsShowNoTimestampsError', requireJsShowNoTimestampsError);
	} else {
	conf.client = {requireJsShowNoTimestampsError};
	}
	}

	/**
	* Configure the 'files' and 'proxies' configuration attributes.
	* These are concatenated into a single file by karma-concat-js.
	*/
	function configureFiles(conf) {
	overrideConfigValue(conf, 'files', []);
	overrideConfigValue(conf, 'exclude', []);
	overrideConfigValue(conf, 'proxies', {});

	// Static files are added to the files array but configured to not be included,
	// so karma-concat-js does not included them in the bundle. Note that we need
	// to add the static files before adding the included files as we don't want
	// to overwrite included files (changing from included to not included).
	[
	// BEGIN STATIC FILES
	TMPL_static_files
	// END STATIC FILES
	].forEach((f) => {
	// In Windows, the runfile will probably not be symlinked. Se we need to
	// serve the real file through karma, and proxy calls to the expected file
	// location in the runfiles to the real file.
	const resolvedFile = runfiles.resolve(f);
	conf.files.push({pattern: resolvedFile, included: false});
	// Prefixing the proxy path with '/absolute' allows karma to load local
	// files. This doesn't see to be an official API.
	// https://github.com/karma-runner/karma/issues/2703
	conf.proxies['/base/' + f] = '/absolute' + resolvedFile;
	});

	[
	// BEGIN BOOTSTRAP FILES
	TMPL_bootstrap_files
	// END BOOTSTRAP FILES
	// BEGIN USER FILES
	TMPL_user_files
	// END USER FILES
	].forEach(f => conf.files.push(runfiles.resolve(f)))

	var requireConfigContent = `
	// A simplified version of Karma's requirejs.config.tpl.js for use with Karma under Bazel.
	// This does an explicit \`require\` on each test script in the files, otherwise nothing will be loaded.
	(function(){
	var runtimeFiles = [
	// BEGIN RUNTIME FILES
	TMPL_runtime_files
	// END RUNTIME FILES
	].map(function(file) { return file.replace(/\\.js$/, ''); });
	var allFiles = [
	// BEGIN USER FILES
	TMPL_user_files
	// END USER FILES
	];
	var allTestFiles = [];
	allFiles.forEach(function (file) {
	if (/[^a-zA-Z0-9](spec\|test)\\.js$/i.test(file) && !/\\/node_modules\\//.test(file)) {
	allTestFiles.push(file.replace(/\\.js$/, ''))
	}
	});
	require(runtimeFiles, function() { return require(allTestFiles, window.__karma__.start); });
	})();
	`;

	const requireConfigFile =
	tmp.fileSync({keep: false, postfix: '.js', dir: process.env['TEST_TMPDIR']});
	fs.writeFileSync(requireConfigFile.name, requireConfigContent);
	conf.files.push(requireConfigFile.name);
	}

	/**
	* Configure karma under karma_web_test_suite.
	* `browsers` and `customLaunchers` are setup by Bazel.
	*/
	function configureTsWebTestSuiteConfig(conf) {
	// WEB_TEST_METADATA is configured in rules_webtesting based on value
	// of the browsers attribute passed to karms_web_test_suite
	// We setup the karma configuration based on the values in this object
	if (!process.env['WEB_TEST_METADATA']) {
	// This is a karma_web_test rule since there is no WEB_TEST_METADATA
	return;
	}

	overrideConfigValue(conf, 'browsers', []);
	overrideConfigValue(conf, 'customLaunchers', null);

	const webTestMetadata = require(runfiles.resolve(process.env['WEB_TEST_METADATA']));
	log_verbose(`WEB_TEST_METADATA: ${JSON.stringify(webTestMetadata, null, 2)}`);
	if (webTestMetadata['environment'] === 'local') {
	// When a local chrome or firefox browser is chosen such as
	// "@io_bazel_rules_webtesting//browsers:chromium-local" or
	// "@io_bazel_rules_webtesting//browsers:firefox-local"
	// then the 'environment' will equal 'local' and
	// 'webTestFiles' will contain the path to the binary to use
	const extractExe = findNamedFile(webTestMetadata, 'EXTRACT_EXE');
	webTestMetadata['webTestFiles'].forEach(webTestFiles => {
	const webTestNamedFiles = webTestFiles['namedFiles'];
	const archiveFile = webTestFiles['archiveFile'];
	if (webTestNamedFiles['CHROMIUM']) {
	// When karma is configured to use Chrome it will look for a CHROME_BIN
	// environment variable.
	if (archiveFile) {
	process.env.CHROME_BIN =
	extractWebArchive(extractExe, archiveFile, webTestNamedFiles['CHROMIUM']);
	} else {
	try {
	process.env.CHROME_BIN = runfiles.resolve(webTestNamedFiles['CHROMIUM']);
	} catch {
	// Fail as this file is expected to be in runfiles
	throw new Error(`Failed to resolve rules_webtesting Chromium binary '${
	webTestNamedFiles['CHROMIUM']}' in runfiles`);
	}
	}
	const browser = process.env['DISPLAY'] ? 'Chrome' : 'ChromeHeadless';
	if (!supportChromeSandboxing()) {
	const launcher = 'CustomChromeWithoutSandbox';
	conf.customLaunchers = {[launcher]: {base: browser, flags: ['--no-sandbox']}};
	conf.browsers.push(launcher);
	} else {
	conf.browsers.push(browser);
	}
	}
	if (webTestNamedFiles['FIREFOX']) {
	// When karma is configured to use Firefox it will look for a
	// FIREFOX_BIN environment variable.
	if (archiveFile) {
	process.env.FIREFOX_BIN =
	extractWebArchive(extractExe, archiveFile, webTestNamedFiles['FIREFOX']);
	} else {
	try {
	process.env.FIREFOX_BIN = runfiles.resolve(webTestNamedFiles['FIREFOX']);
	} catch {
	// Fail as this file is expected to be in runfiles
	throw new Error(`Failed to resolve rules_webtesting Firefox binary '${
	webTestNamedFiles['FIREFOX']}' in runfiles`);
	}
	}
	conf.browsers.push(process.env['DISPLAY'] ? 'Firefox' : 'FirefoxHeadless');
	}
	});
	} else {
	throw new Error(`Unknown WEB_TEST_METADATA environment '${webTestMetadata['environment']}'`);
	}

	if (!conf.browsers.length) {
	throw new Error('No browsers configured in web test suite');
	}
	}

	function configureTsWebTestConfig(conf) {
	if (process.env['WEB_TEST_METADATA']) {
	// This is a karma_web_test_suite rule since there is a WEB_TEST_METADATA
	return;
	}

	// Fallback to using the system local chrome if no valid browsers have been
	// configured above
	if (!conf.browsers \|\| !conf.browsers.length) {
	console.warn('No browsers configured. Configuring Karma to use system Chrome.');
	conf.browsers = [process.env['DISPLAY'] ? 'Chrome' : 'ChromeHeadless'];
	}
	}

	function configureFormatError(conf) {
	conf.formatError = (msg) => {
	// This is a bazel specific formatError that removes the workspace
	// name from stack traces.
	// Look for filenames of the format "(<filename>:<row>:<column>"
	const FILENAME_REGEX = /\(([^:\n\r]+)(:\d+:\d+)/gm;
	msg = msg.replace(FILENAME_REGEX, (_, p1, p2) => {
	if (p1.startsWith('../')) {
	// Remove all leading "../"
	while (p1.startsWith('../')) {
	p1 = p1.substr(3);
	}
	} else {
	// Remove workspace name(angular, ngdeps etc.) from the beginning.
	const index = p1.indexOf('/');
	if (index >= 0) {
	p1 = p1.substr(index + 1);
	}
	}
	return '(' + p1 + p2;
	});
	return msg + '\n\n';
	};
	}

	module.exports = function(config) {
	let conf = {};

	// Import the user's base karma configuration if specified
	if (configPath) {
	const baseConf = require(runfiles.resolve(configPath));
	if (typeof baseConf !== 'function') {
	throw new Error(
	'Invalid base karma configuration. Expected config function to be exported.');
	}
	const originalSetConfig = config.set;
	config.set = function(c) {
	conf = c;
	};
	baseConf(config);
	config.set = originalSetConfig;
	log_verbose(`base karma configuration: ${JSON.stringify(conf, null, 2)}`);
	}

	configureBazelConfig(config, conf);
	configureFiles(conf);
	configureTsWebTestSuiteConfig(conf);
	configureTsWebTestConfig(conf);
	configureFormatError(conf);

	log_verbose(`karma configuration: ${JSON.stringify(conf, null, 2)}`);

	config.set(conf);
	}
	} catch (e) {
	console.error('Error in karma configuration', e.toString());
	throw e;
	}