fix #17: add a stream output option

README.md

@@ -45,14 +45,33 @@ b.plugin(require('css-modulesify'), {
 b.bundle();
 ```
 
+```js
+// or, get the output as a stream
+var b = require('browserify')();
+var fs = require('fs');
+
+b.add('./main.js');
+b.plugin(require('css-modulesify'), {
+  rootDir: __dirname
+});
+
+var bundle = b.bundle()
+bundle.on('css stream', function (css) {
+  css.pipe(fs.createWriteStream('mycss.css'));
+});
+```
+
 ### Options:
 
 - `rootDir`: absolute path to your project's root directory. This is optional but providing it will result in better generated classnames.
-- `output`: path to write the generated css.
+- `output`: path to write the generated css. If not provided, you'll need to listen to the `'css stream'` event on the bundle to get the output.
 - `jsonOutput`: optional path to write a json manifest of classnames.
 - `use`: optional array of postcss plugins (by default we use the css-modules core plugins).
 - `generateScopedName`: (API only) a function to override the default behaviour of creating locally scoped classnames.
 
+### Events
+- `b.bundle().on('css stream', callback)` The callback is called with a readable stream containing the compiled CSS. You can write this to a file.
+
 ## Using CSS Modules on the backend
 
 If you want to use CSS Modules in server-generated templates there are a couple of options:

index.js

@@ -5,6 +5,7 @@ var Core = require('css-modules-loader-core');
 var FileSystemLoader = require('css-modules-loader-core/lib/file-system-loader');
 var assign = require('object-assign');
 var stringHash = require('string-hash');
+var ReadableStream = require('stream').Readable;
 
 
 /*
@@ -96,10 +97,6 @@ module.exports = function (browserify, options) {
   if (!rootDir) { rootDir = process.cwd(); }
 
   var cssOutFilename = options.output || options.o;
-  if (!cssOutFilename) {
-    throw new Error('css-modulesify needs the --output / -o option (path to output css file)');
-  }
-
   var jsonOutFilename = options.json || options.jsonOutput;
 
   // PostCSS plugins passed to FileSystemLoader
@@ -143,6 +140,10 @@ module.exports = function (browserify, options) {
     return plugin;
   });
 
+  // the compiled CSS stream needs to be avalible to the transform,
+  // but re-created on each bundle call.
+  var compiledCssStream;
+
   function transform (filename) {
     // only handle .css files
     if (!cssExt.test(filename)) {
@@ -164,6 +165,8 @@ module.exports = function (browserify, options) {
         // store this file's source to be written out to disk later
         sourceByFile[filename] = loader.finalSource;
 
+        compiledCssStream.push(loader.finalSource);
+
         self.queue(output);
         self.queue(null);
       }, function (err) {
@@ -177,17 +180,32 @@ module.exports = function (browserify, options) {
   });
 
   browserify.on('bundle', function (bundle) {
+    // on each bundle, create a new stream b/c the old one might have ended
+    compiledCssStream = new ReadableStream();
+    compiledCssStream._read = function () {};
+
+    bundle.emit('css stream', compiledCssStream);
+
     bundle.on('end', function () {
       // Combine the collected sources into a single CSS file
-      var css = Object.keys(sourceByFile).map(function (file) {
-        return sourceByFile[file];
-      }).join('\n');
-
-      fs.writeFile(cssOutFilename, css, function (err) {
-        if (err) {
-          browserify.emit('error', err);
-        }
-      });
+      var files = Object.keys(sourceByFile);
+      var css;
+
+      // end the output stream
+      compiledCssStream.push(null);
+
+      // write the css file
+      if (cssOutFilename) {
+        css = files.map(function (file) {
+          return sourceByFile[file];
+        }).join('\n');
+
+        fs.writeFile(cssOutFilename, css, function (err) {
+          if (err) {
+            browserify.emit('error', err);
+          }
+        });
+      }
 
       // write the classname manifest
       if (jsonOutFilename) {

tests/cases/multiple-js-files/expected.css

@@ -0,0 +1,3 @@
+._simple_styles__foo {
+  color: #F00;
+}

tests/cases/multiple-js-files/main.js

@@ -0,0 +1 @@
+module.exports = require('../simple/main.js');

tests/index.js

@@ -34,8 +34,7 @@ function runTestCase (dir) {
 
     b.bundle(function (err) {
       if (err) {
-        console.error(err);
-        return t.fail('Unexpected error');
+        t.error(err, 'should not error');
       }
 
       t.end();

tests/stream-output.js

@@ -0,0 +1,59 @@
+var tape = require('tape');
+
+var browserify = require('browserify');
+var proxyquire = require('proxyquire');
+var fs = require('fs');
+var path = require('path');
+
+var casesDir = path.join(__dirname, 'cases');
+var simpleCaseDir = path.join(casesDir, 'simple');
+var cssFilesTotal = 1;
+var cssOutFilename = 'out.css';
+
+tape('stream output', function (t) {
+  var fakeFs = {
+    writeFile: function (filename, content, cb) {
+      var expected = fs.readFileSync(path.join(simpleCaseDir, 'expected.css'), 'utf8');
+
+      t.equal(filename, cssOutFilename, 'correct output filename');
+      t.equal(content, expected, 'output matches expected');
+      cb();
+    }
+  };
+
+  var cssModulesify = proxyquire('../', {
+    fs: fakeFs
+  });
+
+  t.plan(cssFilesTotal * 2 + 1);
+
+  var cssFilesCount = 0;
+  browserify(path.join(simpleCaseDir, 'main.js'))
+    .plugin(cssModulesify, {
+      rootDir: path.join(simpleCaseDir)
+    })
+    .on('error', t.error)
+    .bundle(function noop () {})
+      .on('css stream', function (stream) {
+        stream
+          .on('data', function onData (css) {
+            var cssString = css.toString();
+            // just get the first class name, use that as an id
+            var cssId = cssString.split('\n')[0].split(' ')[0];
+
+            t.ok(
+              ++cssFilesCount <= cssFilesTotal
+            , 'emits data for ' + cssId
+            );
+
+            t.ok(
+              cssString.indexOf('._styles') === 0
+            , 'emits compiled css for ' + cssId
+            );
+          })
+          .on('end', function onEnd () {
+            t.pass('ends the stream');
+          })
+          .on('error', t.error);
+      });
+});