Test count value in command decoration

This adds tests to ensure the appropriate functioning of the count
option of the _nvim_rpc_spec when using the command decorator.

test/test_decorators.py

@@ -0,0 +1,30 @@
+from nose.tools import with_setup, eq_ as eq, ok_ as ok
+
+from neovim.plugin.decorators import command
+
+
+def test_command_count():
+    def function():
+        "A dummy function to decorate."
+        return
+
+    # ensure absence with default value of None
+    decorated = command('test')(function)
+    ok('count' not in decorated._nvim_rpc_spec['opts'])
+
+    # ensure absence with explicit value of None
+    count_value = None
+    decorated = command('test', count=count_value)(function)
+    ok('count' not in decorated._nvim_rpc_spec['opts'])
+
+    # Test presesence with value of 0
+    count_value = 0
+    decorated = command('test', count=count_value)(function)
+    ok('count' in decorated._nvim_rpc_spec['opts'])
+    eq(decorated._nvim_rpc_spec['opts']['count'], count_value)
+
+    # Test presence with value of 1
+    count_value = 1
+    decorated = command('test', count=count_value)(function)
+    ok('count' in decorated._nvim_rpc_spec['opts'])
+    eq(decorated._nvim_rpc_spec['opts']['count'], count_value)