Use newer ES syntax where possible

As detected via XO. Also apply other XO fixes.

api.js

@@ -45,9 +45,8 @@ class Api extends Emittery {
 		this._precompiler = null;
 	}
 
-	run(files, runtimeOptions) {
+	run(files, runtimeOptions = {}) {
 		const apiOptions = this.options;
-		runtimeOptions = runtimeOptions || {};
 
 		// Each run will have its own status. It can only be created when test files
 		// have been found.
@@ -161,9 +160,10 @@ class Api extends Emittery {
 											if (cachePath) {
 												acc[realpath] = cachePath;
 											}
-										} catch (err) {
-											throw Object.assign(err, {file});
+										} catch (error) {
+											throw Object.assign(error, {file});
 										}
+
 										return acc;
 									}, {})
 								};
@@ -175,6 +175,7 @@ class Api extends Emittery {
 						if (apiOptions.concurrency > 0) {
 							concurrency = apiOptions.concurrency;
 						}
+
 						if (apiOptions.serial) {
 							concurrency = 1;
 						}
@@ -198,6 +199,7 @@ class Api extends Emittery {
 								} else {
 									options.precompiled = {};
 								}
+
 								if (runtimeOptions.updateSnapshots) {
 									// Don't use in Object.assign() since it'll override options.updateSnapshots even when false.
 									options.updateSnapshots = true;
@@ -245,6 +247,7 @@ class Api extends Emittery {
 			filename => {
 				throw new Error(`Cannot apply full precompilation, possible bad usage: ${filename}`);
 			};
+
 		let precompileEnhancementsOnly = () => null;
 		if (compileEnhancements) {
 			precompileEnhancementsOnly = this.options.extensions.enhancementsOnly.length > 0 ?

bench/run.js

@@ -101,7 +101,7 @@ for (let i = 0; i < 11; i++) {
 const results = {};
 
 Promise.each(combined, definition => {
-	const args = definition.args;
+	const {args} = definition;
 
 	return runTests(args).then(result => {
 		const key = result.args.join(' ');

lib/assert.js

@@ -221,10 +221,7 @@ function assertExpectations({assertion, actual, expectations, message, prefix, s
 }
 
 function wrapAssertions(callbacks) {
-	const pass = callbacks.pass;
-	const pending = callbacks.pending;
-	const fail = callbacks.fail;
-
+	const {pass, pending, fail} = callbacks;
 	const noop = () => {};
 
 	const assertions = {
@@ -336,6 +333,7 @@ function wrapAssertions(callbacks) {
 					try {
 						retval.catch(noop);
 					} catch (_) {}
+
 					fail(this, new AssertionError({
 						assertion: 'throws',
 						message,
@@ -539,6 +537,7 @@ function wrapAssertions(callbacks) {
 			} else if (optionsOrMessage) {
 				options.id = optionsOrMessage.id;
 			}
+
 			options.expected = expected;
 			options.message = message;
 
@@ -633,6 +632,7 @@ function wrapAssertions(callbacks) {
 					values: [formatWithLabel('Called with:', string)]
 				});
 			}
+
 			if (!(regex instanceof RegExp)) {
 				throw new AssertionError({
 					assertion: 'regex',
@@ -663,6 +663,7 @@ function wrapAssertions(callbacks) {
 					values: [formatWithLabel('Called with:', string)]
 				});
 			}
+
 			if (!(regex instanceof RegExp)) {
 				throw new AssertionError({
 					assertion: 'notRegex',
@@ -687,4 +688,5 @@ function wrapAssertions(callbacks) {
 
 	return Object.assign(assertions, enhancedAssertions);
 }
+
 exports.wrapAssertions = wrapAssertions;

lib/ava-files.js

@@ -101,9 +101,7 @@ const getDefaultIgnorePatterns = () => defaultIgnore.map(dir => `${dir}/**/*`);
 const matchable = process.platform === 'win32' ? slash : (path => path);
 
 class AvaFiles {
-	constructor(options) {
-		options = options || {};
-
+	constructor(options = {}) {
 		let files = (options.files || []).map(file => {
 			// `./` should be removed from the beginning of patterns because
 			// otherwise they won't match change events from Chokidar
@@ -121,6 +119,7 @@ class AvaFiles {
 		if (files.length === 0) {
 			files = defaultIncludePatterns(this.extensionPattern);
 		}
+
 		this.files = files;
 		this.sources = options.sources || [];
 		this.cwd = options.cwd || process.cwd();
@@ -202,7 +201,7 @@ class AvaFiles {
 	}
 
 	isTest(filePath) {
-		const excludePatterns = this.excludePatterns;
+		const {excludePatterns} = this;
 		const initialPatterns = this.files.concat(excludePatterns);
 
 		// Like in `api.js`, tests must be `.js` files and not start with `_`

lib/babel-pipeline.js

@@ -114,6 +114,7 @@ function hashPartialTestConfig({babelrc, config, options: {plugins, presets}}, p
 			inputs.push(stripBomBuf(fs.readFileSync(babelrc)));
 		}
 	}
+
 	if (config) {
 		inputs.push(config, stripBomBuf(fs.readFileSync(config)));
 	}
@@ -196,16 +197,20 @@ function build(projectDir, cacheDir, userOptions, compileEnhancements) {
 		if (!testOptions.plugins.some(containsAsyncGenerators)) { // TODO: Remove once Babel can parse this syntax unaided.
 			testOptions.plugins.unshift(createConfigItem('@babel/plugin-syntax-async-generators', 'plugin'));
 		}
+
 		if (!testOptions.plugins.some(containsObjectRestSpread)) { // TODO: Remove once Babel can parse this syntax unaided.
 			testOptions.plugins.unshift(createConfigItem('@babel/plugin-syntax-object-rest-spread', 'plugin'));
 		}
+
 		if (!testOptions.plugins.some(containsOptionalCatchBinding)) { // TODO: Remove once Babel can parse this syntax unaided.
 			testOptions.plugins.unshift(createConfigItem('@babel/plugin-syntax-optional-catch-binding', 'plugin'));
 		}
+
 		if (ensureStage4 && !testOptions.presets.some(containsStage4)) {
 			// Apply last.
 			testOptions.presets.unshift(createConfigItem('../stage-4', 'preset'));
 		}
+
 		if (compileEnhancements && !testOptions.presets.some(containsTransformTestFiles)) {
 			// Apply first.
 			testOptions.presets.push(createConfigItem('@ava/babel-preset-transform-test-files', 'preset', {powerAssert: true}));

lib/chalk.js

@@ -6,12 +6,15 @@ exports.get = () => {
 	if (!ctx) {
 		throw new Error('Chalk has not yet been configured');
 	}
+
 	return ctx;
 };
+
 exports.set = options => {
 	if (ctx) {
 		throw new Error('Chalk has already been configured');
 	}
+
 	ctx = new Chalk(options);
 	return ctx;
 };

lib/code-excerpt.js

@@ -8,15 +8,12 @@ const chalk = require('./chalk').get();
 const formatLineNumber = (lineNumber, maxLineNumber) =>
 	' '.repeat(Math.max(0, String(maxLineNumber).length - String(lineNumber).length)) + lineNumber;
 
-module.exports = (source, options) => {
+module.exports = (source, options = {}) => {
 	if (!source.isWithinProject || source.isDependency) {
 		return null;
 	}
 
-	const file = source.file;
-	const line = source.line;
-
-	options = options || {};
+	const {file, line} = source;
 	const maxWidth = options.maxWidth || 80;
 
 	let contents;

lib/context-ref.js

@@ -31,6 +31,7 @@ class LateBinding extends ContextRef {
 		if (!this.bound) {
 			this.set(clone(this.ref.get()));
 		}
+
 		return super.get();
 	}
 

lib/create-chain.js

@@ -2,9 +2,10 @@
 const chainRegistry = new WeakMap();
 
 function startChain(name, call, defaults) {
-	const fn = function () {
-		call(Object.assign({}, defaults), Array.from(arguments));
+	const fn = (...args) => {
+		call(Object.assign({}, defaults), args);
 	};
+
 	Object.defineProperty(fn, 'name', {value: name});
 	chainRegistry.set(fn, {call, defaults, fullName: name});
 	return fn;
@@ -15,9 +16,10 @@ function extendChain(prev, name, flag) {
 		flag = name;
 	}
 
-	const fn = function () {
-		callWithFlag(prev, flag, Array.from(arguments));
+	const fn = (...args) => {
+		callWithFlag(prev, flag, args);
 	};
+
 	const fullName = `${chainRegistry.get(prev).fullName}.${name}`;
 	Object.defineProperty(fn, 'name', {value: fullName});
 	prev[name] = fn;
@@ -55,6 +57,7 @@ function createHookChain(hook, isAfterHook) {
 		extendChain(hook.always, 'skip', 'skipped');
 		extendChain(hook.always.cb, 'skip', 'skipped');
 	}
+
 	return hook;
 }
 
@@ -107,4 +110,5 @@ function createChain(fn, defaults) {
 
 	return root;
 }
+
 module.exports = createChain;

lib/enhance-assert.js

@@ -37,10 +37,11 @@ const enhanceAssert = (pass, fail, assertions) => {
 	return empower(assertions, {
 		destructive: true,
 		onError(event) {
-			const error = event.error;
+			const {error} = event;
 			if (event.powerAssertContext) { // Context may be missing in internal tests.
 				error.statements = formatter(event.powerAssertContext);
 			}
+
 			fail(this, error);
 		},
 		onSuccess() {
@@ -50,4 +51,5 @@ const enhanceAssert = (pass, fail, assertions) => {
 		bindReceiver: false
 	});
 };
+
 module.exports = enhanceAssert;

lib/extensions.js

@@ -19,6 +19,7 @@ module.exports = (enhancementsOnly, babelConfig) => {
 			seen.add('js');
 			full.push('js');
 		}
+
 		if (!babelConfig && enhancementsOnly.length === 0) {
 			seen.add('js');
 			enhancementsOnly.push('js');

lib/load-config.js

@@ -39,6 +39,7 @@ function loadConfig(defaults = {}) {
 		if (fileConf && typeof fileConf.then === 'function') {
 			throw new TypeError('ava.config.js must not export a promise');
 		}
+
 		if (!isPlainObject(fileConf) && typeof fileConf !== 'function') {
 			throw new TypeError('ava.config.js must export a plain object or factory function');
 		}
@@ -48,15 +49,18 @@ function loadConfig(defaults = {}) {
 			if (fileConf && typeof fileConf.then === 'function') {
 				throw new TypeError('Factory method exported by ava.config.js must not return a promise');
 			}
+
 			if (!isPlainObject(fileConf)) {
 				throw new TypeError('Factory method exported by ava.config.js must return a plain object');
 			}
 		}
+
 		if ('ava' in fileConf) {
 			throw new Error('Encountered \'ava\' property in ava.config.js; avoid wrapping the configuration');
 		}
 	}
 
 	return Object.assign({}, defaults, fileConf, packageConf, {projectDir});
 }
+
 module.exports = loadConfig;

lib/reporters/format-serialized-error.js

@@ -23,4 +23,5 @@ function formatSerializedError(error) {
 	formatted = trimOffNewlines(formatted);
 	return {formatted, printMessage};
 }
+
 module.exports = formatSerializedError;

lib/reporters/improper-usage-messages.js

@@ -7,7 +7,7 @@ exports.forError = error => {
 		return null;
 	}
 
-	const assertion = error.assertion;
+	const {assertion} = error;
 	if (assertion === 'throws' || assertion === 'notThrows') {
 		return `Try wrapping the first argument to \`t.${assertion}()\` in a function:
 
@@ -19,8 +19,7 @@ Visit the following URL for more details:
 	}
 
 	if (assertion === 'snapshot') {
-		const name = error.improperUsage.name;
-		const snapPath = error.improperUsage.snapPath;
+		const {name, snapPath} = error.improperUsage;
 
 		if (name === 'ChecksumError') {
 			return `The snapshot file is corrupted.
@@ -39,8 +38,7 @@ Please run AVA again with the ${chalk.cyan('--update-snapshots')} flag to upgrad
 		}
 
 		if (name === 'VersionMismatchError') {
-			const snapVersion = error.improperUsage.snapVersion;
-			const expectedVersion = error.improperUsage.expectedVersion;
+			const {snapVersion, expectedVersion} = error.improperUsage;
 			const upgradeMessage = snapVersion < expectedVersion ?
 				`Please run AVA again with the ${chalk.cyan('--update-snapshots')} flag to upgrade.` :
 				'You should upgrade AVA.';