Add local babel workflow (#25)

* Add local babel workflow

* update README

README.md

@@ -30,6 +30,12 @@ If you want to run **all** the tests, run
 node lib/run-tests I_AM_SURE
 ```
 
+If you want to run against a local copy of babel repo (useful for debugging):
+
+```
+BABEL_PATH=../babel node lib/run-tests [pattern]
+```
+
 ## Download babel/babel master test262 artifact
 
 ```

lib/run-tests/contextualize-require.js

@@ -0,0 +1,13 @@
+const path = require('path');
+
+const babelPath = process.env.BABEL_PATH ?
+    path.resolve(process.cwd(), process.env.BABEL_PATH) :
+    undefined;
+
+module.exports = function contextualizeRequire(path) {
+    if (!babelPath) {
+        return require(path);
+    }
+    const newPath = `${babelPath}/${path.replace('@babel/', 'packages/babel-')}`;
+    return require(newPath);
+};

lib/run-tests/get-babel-plugins.js

@@ -1,10 +1,12 @@
 "use strict";
 
+const requireBabel = require('./contextualize-require');
+
 const featuresToPlugins = {
-  "class-fields-public": require("@babel/plugin-proposal-class-properties"),
-  "class-methods-private": require("@babel/plugin-proposal-private-methods"),
-  "numeric-separator-literal": require("@babel/plugin-proposal-numeric-separator"),
-  //"import.meta": require("@babel/plugin-syntax-import-meta"),
+  "class-fields-public": requireBabel("@babel/plugin-proposal-class-properties"),
+  "class-methods-private": requireBabel("@babel/plugin-proposal-private-methods"),
+  "numeric-separator-literal": requireBabel("@babel/plugin-proposal-numeric-separator"),
+  //"import.meta": requireBabel("@babel/plugin-syntax-import-meta"),
 };
 
 const defaultPlugins = [

lib/run-tests/transpile.js

@@ -1,7 +1,8 @@
 "use strict";
 
-const { transformSync, loadOptions } = require("@babel/core");
-const presetEnv = require("@babel/preset-env");
+const requireBabel = require('./contextualize-require');
+const { transformSync, loadOptions } = requireBabel("@babel/core");
+const presetEnv = requireBabel("@babel/preset-env");
 
 const getBabelPlugins = require("./get-babel-plugins");