Add allowance for 'use strict', addresses issue #85

lib/main.js

@@ -269,6 +269,7 @@ Lambda.prototype._setEnvironmentVars = function (program, codeDirectory) {
   var configValues = fs.readFileSync(program.configFile);
   var prefix = '////////////////////////////////////\n// "Environment Variables"\n';
   var config = dotenv.parse(configValues);
+  var contentStr = contents.toString();
 
   for (var k in config) {
     if (!config.hasOwnProperty(k)) {
@@ -280,7 +281,14 @@ Lambda.prototype._setEnvironmentVars = function (program, codeDirectory) {
   }
   prefix += '////////////////////////////////////\n\n';
 
-  fs.writeFileSync(handlerFileName, prefix + contents.toString());
+  // If the first line of the file is 'use strict', append after
+  if (contentStr.trim().indexOf('use strict') === 1) {
+    contentStr = contentStr.replace(/([`'"]use strict[`'"][;]?)/, '$1\n' + prefix);
+  } else {
+    contentStr = prefix + contentStr;
+  }
+
+  fs.writeFileSync(handlerFileName, contentStr);
 };
 
 Lambda.prototype._uploadExisting = function(lambda, params, cb) {

test/main.js

@@ -240,4 +240,31 @@ describe('node-lambda', function () {
     });
 
   });
+
+  describe('environment variable injection - "use strict" allowance', function () {
+    beforeEach(function () {
+      // Prep...
+      fs.writeFileSync('tmp.env', 'FOO=bar\nBAZ=bing\n');
+      fs.writeFileSync('test.js', '\'use strict\';');
+    });
+
+    afterEach(function () {
+      fs.unlinkSync('tmp.env');
+      fs.unlinkSync('test.js');
+    });
+
+    it('should inject environment variables at the top of the entry point file', function () {
+
+      // Run it...
+      lambda._setEnvironmentVars({
+        configFile: 'tmp.env',
+        handler: 'test.handler',
+      }, process.cwd());
+
+      assert.equal(fs.readFileSync('test.js').toString(), '\'use strict\';\n////////////////////////////////////\n' +
+        '// "Environment Variables"\nprocess.env["FOO"]="bar";\n' +
+        'process.env["BAZ"]="bing";\n////////////////////////////////////\n\n');
+    });
+
+  });
 });