[WIP] Language plugin

package.json

@@ -1,7 +1,7 @@
 {
   "name": "relay",
   "description": "A framework for building data-driven React applications.",
-  "version": "1.4.1",
+  "version": "1.4.1-plugin.2",
   "license": "MIT",
   "homepage": "https://facebook.github.io/relay/",
   "bugs": "https://github.com/facebook/relay/issues",

packages/babel-plugin-relay/BabelPluginRelay.js

@@ -40,6 +40,8 @@ export type RelayPluginOptions = {
   snakeCase?: boolean,
   substituteVariables?: boolean,
   validator?: Validator<any>,
+  // Directory as specified by outputDir when running relay-compiler
+  artifactDirectory?: string,
 };
 
 export type BabelState = {

packages/babel-plugin-relay/__tests__/BabelPluginRelay-test.js

@@ -26,14 +26,15 @@ describe('BabelPluginRelay', () => {
   function transformerWithOptions(
     options: RelayPluginOptions,
     environment: 'development' | 'production' = 'production',
+    filename?: string,
   ): string => string {
-    return (text, filename) => {
+    return (text, providedFileName) => {
       const previousEnv = process.env.BABEL_ENV;
       try {
         process.env.BABEL_ENV = environment;
         return babel.transform(text, {
           compact: false,
-          filename,
+          filename: filename || providedFileName,
           parserOpts: {plugins: ['jsx']},
           plugins: [[BabelPluginRelay, options]],
         }).code;
@@ -84,6 +85,17 @@ describe('BabelPluginRelay', () => {
     }),
   );
 
+  generateTestsFromFixtures(
+    `${__dirname}/fixtures-modern-artifact-directory`,
+    transformerWithOptions(
+      {
+        artifactDirectory: '/test/artifacts',
+      },
+      'production',
+      '/testing/Container.js',
+    ),
+  );
+
   describe('`development` option', () => {
     it('tests the hash when `development` is set', () => {
       expect(