Option to reuse build output during plugin development

README.md

@@ -64,6 +64,12 @@ None
 
 * yarn test
 
+## Faster iteration while authoring deploy plugins & configs
+
+When you're working on a deploy plugin or tweaking your deploy config, you often run `ember deploy` repeatedly, and each run usually invokes this plugin to do a full rebuild of your app, even though your app has not changed and the build options are identical.
+
+You can instead reuse the build from the previous `ember deploy` by setting the environment variable `EMBER_CLI_DEPLOY_REUSE_BUILD`. This may make your interactive testing much faster. It's safe to use during development as long as you aren't actively changing your app or altering this module's `environment` or `outputPath`.
+
 ## Why `ember test` doesn't work
 
 Since this is a node-only ember-cli addon, we use mocha for testing and this package does not include many files and devDependencies which are part of ember-cli's typical `ember test` processes.

index.js

@@ -20,6 +20,13 @@ module.exports = {
       build: function(/* context */) {
         var self       = this;
         var outputPath = this.readConfig('outputPath');
+        if (process.env.EMBER_CLI_DEPLOY_REUSE_BUILD) {
+          this.log('reusing build from `' + outputPath, { verbose: true });
+          return RSVP.resolve({
+            distDir: outputPath,
+            distFiles: glob.sync('**/*', { cwd: outputPath, nodir: true })
+          });
+        }
         var buildEnv   = this.readConfig('environment');
 
         var Builder  = this.project.require('ember-cli/lib/models/builder');

tests/.eslintrc.js

@@ -2,6 +2,7 @@ module.exports = {
   globals: {
     "describe": true,
     "beforeEach": true,
+    "afterEach": true,
     "it": true
   },
   env: {

tests/fixtures/fake-build-output/assets/inner-example.css

@@ -0,0 +1 @@
+/* hello world */

tests/fixtures/fake-build-output/top-file-example.js

@@ -0,0 +1 @@
+/* hello world */

tests/index-test.js

@@ -135,11 +135,16 @@ describe('build plugin', function() {
           }
         }
       };
-      plugin.beforeHook(context);
     });
 
+    afterEach(function() {
+      delete process.env.EMBER_CLI_DEPLOY_REUSE_BUILD;
+    });
+
+
     it('builds the app and resolves with distDir and distFiles', function(done) {
       this.timeout(50000);
+      plugin.beforeHook(context);
       assert.isFulfilled(plugin.build(context))
         .then(function(result) {
           assert.deepEqual(result, {
@@ -167,5 +172,26 @@ describe('build plugin', function() {
           done(reason);
         });
     });
+
+    it('can reuse build results and resolve with distDir and distFiles', function(done) {
+      process.env.EMBER_CLI_DEPLOY_REUSE_BUILD = 'true';
+      context.config.build.outputPath = __dirname + '/fixtures/fake-build-output';
+      plugin.beforeHook(context);
+
+      assert.isFulfilled(plugin.build(context))
+        .then(function(result) {
+          assert.deepEqual(result, {
+            distDir: __dirname + '/fixtures/fake-build-output',
+            distFiles: [
+              'assets/inner-example.css',
+              'top-file-example.js'
+            ]
+          });
+          done();
+        }).catch(function(reason){
+          done(reason);
+        });
+    });
+
   });
 });