cache babel-transpiled code

lib/babel.js

@@ -1,6 +1,13 @@
 'use strict';
 
+var cacheDir = require('xdg-basedir').cache;
+var tmpDir = require('os-tmpdir');
 var debug = require('debug')('ava');
+var hasha = require('hasha');
+var cacha = require('cacha');
+var join = require('path').join;
+
+var cache = cacha(join(cacheDir || tmpdir(), 'ava'));
 
 var opts = JSON.parse(process.argv[2]);
 
@@ -36,24 +43,17 @@ sourceMapSupport.install({
 	}
 });
 
-var createEspowerPlugin = require('babel-plugin-espower/create');
 var requireFromString = require('require-from-string');
 var loudRejection = require('loud-rejection/api')(process);
 var serializeError = require('serialize-error');
-var babel = require('babel-core');
 var send = require('./send');
 
 var testPath = opts.file;
 
-// initialize power-assert
-var powerAssert = createEspowerPlugin(babel, {
-	patterns: require('./enhance-assert').PATTERNS
-});
-
 // if generators are not supported, use regenerator
 var options = {
 	presets: ['stage-2', 'es2015'],
-	plugins: [powerAssert, 'transform-runtime'],
+	plugins: ['transform-runtime'],
 	sourceMaps: true
 };
 
@@ -70,11 +70,43 @@ if (inputSourceMap) {
 }
 
 // include test file
-var transpiled = babel.transformFileSync(testPath, options);
-sourceMapCache[testPath] = transpiled.map;
-requireFromString(transpiled.code, testPath, {
-	appendPaths: module.paths
-});
+var cachePath = hasha(testPath);
+var hashPath = hasha(testPath) + '_hash';
+
+var prevHash = cache.getSync(hashPath, {encoding: 'utf8'});
+var currHash = hasha.fromFileSync(testPath);
+
+if (prevHash === currHash) {
+	var cached = JSON.parse(cache.getSync(cachePath));
+
+	sourceMapCache[testPath] = cached.map;
+	requireFromString(cached.code, testPath, {
+		appendPaths: module.paths
+	});
+} else {
+	var createEspowerPlugin = require('babel-plugin-espower/create');
+	var babel = require('babel-core');
+
+	// initialize power-assert
+	var powerAssert = createEspowerPlugin(babel, {
+		patterns: require('./enhance-assert').PATTERNS
+	});
+
+	options.plugins.push(powerAssert);
+
+	var transpiled = babel.transformFileSync(testPath, options);
+
+	cache.setSync(hashPath, currHash);
+	cache.setSync(cachePath, JSON.stringify({
+		code: transpiled.code,
+		map: transpiled.map
+	}));
+
+	sourceMapCache[testPath] = transpiled.map;
+	requireFromString(transpiled.code, testPath, {
+		appendPaths: module.paths
+	});
+}
 
 process.on('uncaughtException', function (exception) {
 	send('uncaughtException', {exception: serializeError(exception)});

package.json

@@ -88,6 +88,7 @@
     "babel-preset-stage-2": "^6.3.13",
     "babel-runtime": "^6.3.19",
     "bluebird": "^3.0.0",
+    "cacha": "^1.0.3",
     "chalk": "^1.0.0",
     "co-with-promise": "^4.6.0",
     "core-assert": "^0.1.0",
@@ -97,6 +98,7 @@
     "figures": "^1.4.0",
     "fn-name": "^2.0.0",
     "globby": "^4.0.0",
+    "hasha": "^2.0.2",
     "is-generator-fn": "^1.0.0",
     "is-observable": "^0.1.0",
     "is-promise": "^2.1.0",
@@ -105,6 +107,7 @@
     "meow": "^3.6.0",
     "object-assign": "^4.0.1",
     "observable-to-promise": "^0.1.0",
+    "os-tmpdir": "^1.0.1",
     "plur": "^2.0.0",
     "power-assert-formatter": "^1.3.0",
     "power-assert-renderers": "^0.1.0",
@@ -116,7 +119,8 @@
     "source-map-support": "^0.4.0",
     "squeak": "^1.2.0",
     "time-require": "^0.1.2",
-    "update-notifier": "^0.5.0"
+    "update-notifier": "^0.5.0",
+    "xdg-basedir": "^2.0.0"
   },
   "devDependencies": {
     "coveralls": "^2.11.4",