Add test_001_Output_STRERR() test.

NativeScript/nativescript-cli#793

Author: Vasil Chimev

helpers/_os_lib.py

@@ -1,5 +1,4 @@
-import fileinput
-import os, threading, psutil, time, shutil
+import os, errno, fileinput, time, threading, psutil, shutil
 import platform
 import tarfile
 from time import sleep
@@ -164,6 +163,13 @@ def catAppFile(platform, appName, filePath):
         output = runAUT("ddb device get-file \"Library/Application Support/LiveSync/" + filePath +"\" --app org.nativescript." + appName)
     return output
 
+def remove(file_path):
+    try:
+        os.remove(file_path)
+    except OSError as e:
+        if e.errno != errno.ENOENT: # errno.ENOENT = no such file or directory
+            raise
+
 def uninstall_app(appName):
     output = runAUT("ddb device uninstall org.nativescript." + appName)
     if ("[Uninstalling] Status: RemovingApplication" in output):

tests/output_stderr.py

@@ -0,0 +1,24 @@
+import os, unittest
+
+from helpers._os_lib import remove, runAUT
+from helpers._tns_lib import tnsPath
+
+class Output_STRERR(unittest.TestCase):
+
+    def setUp(self):
+
+        print ""
+        print "#####"
+        print self.id()
+        print "#####"
+        print ""
+
+        remove('stderr.txt');
+
+    def tearDown(self):
+        remove('stderr.txt');
+
+    def test_001_Output_STRERR(self):
+        os.system(tnsPath + " emulate asdf 2>stderr.txt")
+        output = runAUT("cat stderr.txt")
+        assert ("The input is not valid sub-command for 'emulate' command" in output)