Add option urlTransform

- Allow to pass a function to tranform file path to url
   - can transform WSL path to windows path if needed
- url provided to `open` instead of local path to allow usage of http (output files could be written to a served directory)

should fix #18

Author: Léo Bonnargent

src/index.js

@@ -28,6 +28,7 @@ const previewEmail = async (message, options) => {
     id: uuid.v4(),
     open: { wait: false },
     template: templateFilePath,
+    urlTransform: path => `file://${path}`,
     ...options
   };
   debug('message', message, 'options', options);
@@ -52,9 +53,10 @@ const previewEmail = async (message, options) => {
   debug('filePath', filePath);
   await writeFile(filePath, html);
 
-  if (options.open) await open(filePath, options.open);
+  const url = options.urlTransform(filePath);
+  if (options.open) await open(url, options.open);
 
-  return `file://${filePath}`;
+  return url;
 };
 
 module.exports = previewEmail;

test/test.js

@@ -62,3 +62,14 @@ test('does not open in browser', async t => {
   const url = await previewEmail({}, { open: false });
   t.true(typeof url === 'string');
 });
+
+test('transform URL', async t => {
+  const url = await previewEmail(
+    {},
+    {
+      open: false,
+      urlTransform: path => `http://localhost:8000/${path}`
+    }
+  );
+  t.regex(url, /^http:\/\/localhost:8000\//);
+});