Add specific packages into coverageEnv

lib/app.js

@@ -42,6 +42,7 @@ class App {
     this.port = config.port || 8555;             // Port testrpc should listen on
 
     this.copyNodeModules = config.copyNodeModules || false;  // Copy node modules into coverageEnv?
+    this.copyPackages = config.copyPackages || [];           // Only copy specific node_modules packages into coverageEnv
     this.testrpcOptions = config.testrpcOptions || null;     // Options for testrpc-sc
     this.testCommand = config.testCommand || null;           // Optional test command
 
@@ -72,6 +73,14 @@ class App {
       shell.mkdir(this.coverageDir);
       shell.cp('-R', files, this.coverageDir);
 
+      // Add specific node_modules packages.
+      if (!this.copyNodeModules && this.copyPackages.length) {
+        shell.mkdir(this.coverageDir + '/node_modules');
+        this.copyNodeModulesPackages.forEach((nodePackage) => {
+          shell.cp('-rf', 'node_modules/' + nodePackage, this.coverageDir + '/node_modules/');
+        });
+      }
+
       // Load config if present, accomodate common windows naming.
       let truffleConfig;