Fixes #247 - Allow init function in writer plugins.

Author: austinkelleher

src/writers/Writer.js

@@ -10,9 +10,20 @@ var reader = require('../reader');
 var ok = require('assert').ok;
 var equal = require('assert').equal;
 
+async function initWriter (writer, lassoContext) {
+    if (!writer._initialized && writer.impl.init) {
+        await writer.impl.init(lassoContext);
+        writer._initialized = true;
+    }
+}
+
 function Writer(impl) {
     Writer.$super.call(this);
     this.impl = impl || {};
+
+    // Lasso writer `init` function should only be called once. We call it the
+    // first time that either writing a resource or bundle is attempted.
+    this._initialized = false;
 }
 
 Writer.prototype = {
@@ -193,6 +204,7 @@ Writer.prototype = {
         const resourceReader = reader.createResourceReader(path, lassoContext);
 
         try {
+            await initWriter(this, lassoContext);
             const writeResult = await this.impl.writeResource(resourceReader, lassoContext);
             return done(writeResult);
         } catch (err) {
@@ -245,6 +257,7 @@ Writer.prototype = {
     async writeBundles (iteratorFunc, onBundleWrittenCallback, lassoContext) {
         ok(lassoContext, 'lassoContext is required');
 
+        await initWriter(this, lassoContext);
         let promise = Promise.resolve();
 
         iteratorFunc((bundle) => {

test/autotests/plugins/write-bundle/browser.json

@@ -0,0 +1,8 @@
+{
+    "dependencies": [
+        {
+            "type": "js",
+            "path": "./foo.js"
+        }
+    ]
+}

test/autotests/plugins/write-bundle/foo.js

@@ -0,0 +1 @@
+var a = 5;

test/autotests/plugins/write-bundle/package.json

@@ -0,0 +1,4 @@
+{
+    "name": "autotest",
+    "version": "0.0.0"
+}

test/autotests/plugins/write-bundle/plugin.js

@@ -0,0 +1,21 @@
+module.exports = function(lasso, config) {
+    lasso.config.writer = {
+        async init (lassoContext) {
+            module.exports.counter.push('init');
+            await Promise.resolve();
+        },
+
+        async writeBundle (reader, lassoContext) {
+            const bundle = lassoContext.bundle;
+            bundle.url = 'test.com';
+            module.exports.counter.push('writeBundle');
+        },
+
+        async writeResource (reader, lassoContext) {
+            module.exports.counter.push('writeResource');
+            return { url: 'test.com' };
+        }
+    };
+};
+
+module.exports.counter = [];

test/autotests/plugins/write-bundle/test.js

@@ -0,0 +1,24 @@
+var expect = require('chai').expect;
+const plugin = require('./plugin');
+
+exports.getLassoConfig = function() {
+    return {
+        fingerprintsEnabled: false,
+        bundlingEnabled: true,
+        plugins: [plugin]
+    };
+};
+
+exports.getLassoOptions = function() {
+    return {
+        dependencies: [
+            './browser.json'
+        ]
+    };
+};
+
+exports.check = function(lassoPageResult, writerTracker) {
+    expect(plugin.counter).to.deep.equal(['init', 'writeBundle']);
+    expect(lassoPageResult.getJavaScriptFiles().length).to.equal(0);
+    expect(lassoPageResult.getJavaScriptUrls()).to.deep.equal(['test.com']);
+};