feat: make Module.transform configurable from evaluate (#247)

Replacement of #246

src/babel/evaluate.js

@@ -5,6 +5,22 @@ const generator = require('@babel/generator').default;
 const babel = require('@babel/core');
 const Module = require('./module');
 
+function defaultTransformModule(text) {
+  return babel.transformSync(text, {
+    filename: this.filename,
+    plugins: [
+      // Include this plugin to avoid extra config when using { module: false } for webpack
+      '@babel/plugin-transform-modules-commonjs',
+      '@babel/plugin-proposal-export-namespace-from',
+      // We don't support dynamic imports when evaluating, but don't wanna syntax error
+      // This will replace dynamic imports with an object that does nothing
+      require.resolve('./dynamic-import-noop'),
+      [require.resolve('./extract'), { evaluate: true }],
+    ],
+    exclude: /node_modules/,
+  });
+}
+
 const resolve = (path, t, requirements) => {
   const binding = path.scope.getBinding(path.node.name);
 
@@ -58,7 +74,8 @@ const resolve = (path, t, requirements) => {
 module.exports = function evaluate(
   path /* : any */,
   t /* : any */,
-  filename /* : string */
+  filename /* : string */,
+  transformModule /* : (text: string) => { code: string } */ = defaultTransformModule
 ) {
   const requirements = [];
 
@@ -147,21 +164,7 @@ module.exports = function evaluate(
 
   const m = new Module(filename);
 
-  m.transform = function transform(text) {
-    return babel.transformSync(text, {
-      filename: this.filename,
-      plugins: [
-        // Include this plugin to avoid extra config when using { module: false } for webpack
-        '@babel/plugin-transform-modules-commonjs',
-        '@babel/plugin-proposal-export-namespace-from',
-        // We don't support dynamic imports when evaluating, but don't wanna syntax error
-        // This will replace dynamic imports with an object that does nothing
-        require.resolve('./dynamic-import-noop'),
-        [require.resolve('./extract'), { evaluate: true }],
-      ],
-      exclude: /node_modules/,
-    });
-  };
+  m.transform = transformModule;
 
   m.evaluate(
     dedent`