refs #482: Adds an --engine=.. option

It will allow to choice different browser engines, instead of phantomjs

@@ -9,7 +9,9 @@ def resolve(path):
         return resolve(path)
     return path
 
-PHANTOMJS_NATIVE_ARGS = [
+SUPPORTED_ENGINES = {
+    'phantomjs' : {
+        'native_args': [
             'cookies-file',
             'config',
             'debug',
@@ -30,23 +32,47 @@ PHANTOMJS_NATIVE_ARGS = [
             'script-encoding',
             'ssl-protocol',
             'web-security',
-]
+        ],
+        'env_varname': 'PHANTOMJS_EXECUTABLE',
+        'default_exec' : 'phantomjs'
+    }
+}
+
+ENGINE = 'phantomjs'
+ENGINE_ARGS = []
+ENGINE_NATIVE_ARGS = []
+ENGINE_EXECUTABLE = ''
+
 CASPER_ARGS = []
 CASPER_PATH = os.path.abspath(os.path.join(os.path.dirname(resolve(__file__)), '..'))
-PHANTOMJS_ARGS = []
 SYS_ARGS = sys.argv[1:]
 
+# retrieve the engine name
+for arg in SYS_ARGS:
+    if arg.startswith('--engine='):
+        ENGINE = arg[9:].lower()
+        break
+
+if ENGINE in SUPPORTED_ENGINES:
+    ENGINE_NATIVE_ARGS = SUPPORTED_ENGINES[ENGINE]['native_args']
+    ENGINE_EXECUTABLE = os.environ.get(SUPPORTED_ENGINES[ENGINE]['env_varname'], SUPPORTED_ENGINES[ENGINE]['default_exec'])
+else:
+    print('Bad engine name. Only phantomjs and slimerjs are supported')
+    sys.exit(1)
+
+
 for arg in SYS_ARGS:
     found = False
-    for native in PHANTOMJS_NATIVE_ARGS:
+    for native in ENGINE_NATIVE_ARGS:
         if arg.startswith('--%s' % native):
-            PHANTOMJS_ARGS.append(arg)
+            ENGINE_ARGS.append(arg)
             found = True
     if not found:
+        if arg.startswith('--engine=') == False:
             CASPER_ARGS.append(arg)
 
-CASPER_COMMAND = os.environ.get('PHANTOMJS_EXECUTABLE', 'phantomjs').split(' ')
-CASPER_COMMAND.extend(PHANTOMJS_ARGS)
+CASPER_COMMAND = ENGINE_EXECUTABLE.split(' ')
+CASPER_COMMAND.extend(ENGINE_ARGS)
 CASPER_COMMAND.extend([
     os.path.join(CASPER_PATH, 'bin', 'bootstrap.js'),
     '--casper-path=%s' % CASPER_PATH,

@@ -10,5 +10,6 @@ Options:
 --log-level Sets logging level
 --help      Prints this help
 --version   Prints out CasperJS version
+--engine=name Use the given engine. Current supported engine: phantomjs
 
 Read the docs http://docs.casperjs.org/