make "prepare" command configurable

fixes #5

Author: Niall O'Higgins

config/config.html

@@ -1,3 +1,9 @@
+<input type="text" ng-model="config.prepare" />
+<p class="help-text">
+  Select which command should be used to prepare your project. The default is
+  "pip -r requirements.txt". For example, this could be "python setup.py
+  develop" for some projects.
+</p>
 <select ng-model="config.test">
   <option value="python setup.py test">python setup.py test</option>
   <option value="make test">make test</option>

webapp.js

@@ -11,6 +11,10 @@ module.exports = {
       type: String,
       enum: ['none', 'py.test', 'python setup.py test', 'make test'],
       default: 'python setup.py test'
+    },
+    prepare: {
+      type: String,
+      default: 'pip install -r requirements.txt'
     }
   }
 }

worker.js

@@ -9,17 +9,24 @@ module.exports = {
     if (config && config.test !== 'none') {
       test = config.test
     }
+    var defaultPrepare = "pip install -r requirements.txt"
+    var prepare = defaultPrepare
+    if (config && config.prepare) {
+      prepare = config.prepare
+    }
     done(null, {
       path: [path.join(__dirname, 'thirdparty'),
              path.join(venvDir, 'bin')],
       environment: 'virtualenv.py ' + venvDir,
       prepare: function (context, done) {
-        if (fs.existsSync(path.join(context.dataDir, 'requirements.txt'))) {
-          return context.cmd('pip install -r requirements.txt', function (err) {
-            done(err, true)
-          })
+        if (prepare === defaultPrepare && !fs.existsSync(path.join(context.dataDir, 'requirements.txt'))) {
+          // skip if default and no requirements.txt exists
+          // we assume that if you're configuring your own, you'll ensure the file exists
+          return done(null, true)
         }
-        done(null, false)
+        context.cmd(prepare, function (err) {
+          done(err, true)
+        })
       },
       test: test
     })