Enable V8 supported stage-3 syntax, as well as stage-4 syntax

* Enable Babel parser options directly, rather than through Babel syntax plugins
* Enable stage-3 syntax supported in V8
* Enable stage-4 dynamic import syntax

Author: novemberborn

lib/babel-pipeline.js

@@ -58,6 +58,26 @@ function validate(conf) {
 	};
 }
 
+function enableParserPlugins(api) {
+	api.assertVersion(7);
+
+	return {
+		name: 'ava-babel-pipeline-enable-parser-plugins',
+		manipulateOptions(_, parserOpts) {
+			parserOpts.plugins.push(
+				'asyncGenerators',
+				'bigInt',
+				'classPrivateProperties',
+				'classProperties',
+				'dynamicImport',
+				'numericSeparator',
+				'objectRestSpread',
+				'optionalCatchBinding'
+			);
+		}
+	};
+}
+
 // Compare actual values rather than file paths, which should be
 // more reliable.
 function makeValueChecker(ref) {
@@ -118,7 +138,12 @@ function hashPartialTestConfig({babelrc, config, options: {plugins, presets}}, p
 		inputs.push(config, stripBomBuf(fs.readFileSync(config)));
 	}
 
-	for (const {file: {resolved: filename}} of [...plugins, ...presets]) {
+	for (const item of [...plugins, ...presets]) {
+		if (!item.file) {
+			continue;
+		}
+
+		const {file: {resolved: filename}} = item;
 		if (pluginAndPresetHashes.has(filename)) {
 			inputs.push(pluginAndPresetHashes.get(filename));
 			continue;
@@ -168,9 +193,6 @@ function build(projectDir, cacheDir, userOptions, compileEnhancements) {
 	const pluginAndPresetHashes = new Map();
 
 	const ensureStage4 = wantsStage4(userOptions, projectDir);
-	const containsAsyncGenerators = makeValueChecker('@babel/plugin-syntax-async-generators');
-	const containsObjectRestSpread = makeValueChecker('@babel/plugin-syntax-object-rest-spread');
-	const containsOptionalCatchBinding = makeValueChecker('@babel/plugin-syntax-optional-catch-binding');
 	const containsStage4 = makeValueChecker('../stage-4');
 	const containsTransformTestFiles = makeValueChecker('@ava/babel-preset-transform-test-files');
 
@@ -193,17 +215,7 @@ function build(projectDir, cacheDir, userOptions, compileEnhancements) {
 		}
 
 		const {options: testOptions} = partialTestConfig;
-		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'));
-		}
+		testOptions.plugins.push(enableParserPlugins);
 
 		if (ensureStage4 && !testOptions.presets.some(containsStage4)) {
 			// Apply last.

package-lock.json

@@ -61,9 +61,6 @@
 		"@ava/babel-preset-transform-test-files": "^6.0.0",
 		"@babel/core": "^7.5.5",
 		"@babel/generator": "^7.5.5",
-		"@babel/plugin-syntax-async-generators": "^7.2.0",
-		"@babel/plugin-syntax-object-rest-spread": "^7.2.0",
-		"@babel/plugin-syntax-optional-catch-binding": "^7.2.0",
 		"@concordance/react": "^2.0.0",
 		"ansi-escapes": "^4.2.1",
 		"ansi-styles": "^4.0.0",

package.json

@@ -46,12 +46,3 @@ test('includes relative paths in source map', t => {
 		t.end();
 	});
 });
-
-for (const plugin of ['async-generators', 'object-rest-spread', 'optional-catch-binding']) {
-	test(`avoids applying '@babel/plugin-syntax-${plugin}' if already in config`, t => {
-		execCli([], {dirname: `fixture/babel/with-explicit-syntax-plugins/${plugin}`}, err => {
-			t.ifError(err);
-			t.end();
-		});
-	});
-}