Added unit test for _get_cword

test/unit/_get_cword.exp

@@ -0,0 +1,25 @@
+proc setup {} {
+    save_env
+}; # setup()
+
+
+proc teardown {} {
+    assert_env_unmodified
+}; # teardown()
+
+
+setup
+
+
+set test "_get_cword should run without errors"
+assert_bash_exec {_get_cword > /dev/null} $test
+
+
+sync_after_int
+
+
+# See also ./lib/completions/alias.exp.  Here `_get_cword' is actually tested
+# by moving the cursor left into the current word.
+
+
+teardown