allow nosetests without env setup

.travis.yml

@@ -34,7 +34,7 @@ install:
   - pip install .
 script:
   - if [ $CI_TARGET = tests ]; then
-      NVIM_CHILD_ARGV='["nvim", "-u", "NONE", "--embed"]' nosetests;
+      nosetests;
     else
       flake8 neovim;
     fi

README.md

@@ -118,10 +118,16 @@ to use it for the plugin host.
 To run the tests execute
 
 ```sh
-NVIM_CHILD_ARGV='["nvim", "-u", "NONE", "--embed"]' nosetests
+nosetests
+```
+
+This will run the tests in an embedded instance of nvim.
+If you want to test a different version than `nvim` in `$PATH` use
+```sh
+NVIM_CHILD_ARGV='["/path/to/nvim", "-u", "NONE", "--embed"]' nosetests
 ```
 
-Alternatively, if you want to see the state of nvim, you could
+Alternatively, if you want to see the state of nvim, you could use
 
 ```sh
 export NVIM_LISTEN_ADDRESS=/tmp/nvimtest

test/test_common.py

@@ -8,10 +8,15 @@
 
 neovim.setup_logging()
 
-if 'NVIM_CHILD_ARGV' in os.environ:
-    vim = neovim.attach('child', argv=json.loads(os.environ['NVIM_CHILD_ARGV']))
+child_argv = os.environ.get('NVIM_CHILD_ARGV')
+listen_address = os.environ.get('NVIM_LISTEN_ADDRESS')
+if child_argv is None and listen_address is None:
+    child_argv = '["nvim", "-u", "NONE", "--embed"]'
+
+if child_argv is not None:
+    vim = neovim.attach('child', argv=json.loads(child_argv))
 else:
-    vim = neovim.attach('socket', path=os.environ['NVIM_LISTEN_ADDRESS'])
+    vim = neovim.attach('socket', path=listen_address)
 
 if sys.version_info >= (3, 0):
     # For Python3 we decode binary strings as Unicode for compatibility