fix(tests): Remove unnecessary test

Testing that a bad completion directive was being replaced by the
default one was actually testing Cobra's behaviour.  This is unnecessary
especially since that behaviour changed in the 1.2.0 release.  Helm
tests should focus on testing Helm's behaviour.

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

cmd/helm/plugin_test.go

@@ -277,11 +277,6 @@ func TestPluginDynamicCompletion(t *testing.T) {
 		cmd:    "__complete echo -n mynamespace ''",
 		golden: "output/plugin_echo_no_directive.txt",
 		rels:   []*release.Release{},
-	}, {
-		name:   "completion for plugin bad directive",
-		cmd:    "__complete echo ''",
-		golden: "output/plugin_echo_bad_directive.txt",
-		rels:   []*release.Release{},
 	}}
 	for _, test := range tests {
 		settings.PluginsDirectory = "testdata/helmhome/helm/plugins"

cmd/helm/testdata/helmhome/helm/plugins/echo/plugin.complete

@@ -7,8 +7,7 @@ echo "Args received: ${@}"
 
 # Final printout is the optional completion directive of the form :<directive>
 if [ "$HELM_NAMESPACE" = "default" ]; then
-    # Output an invalid directive, which should be ignored
-    echo ":2222"
+    echo ":0"
 # else
     # Don't include the directive, to test it is really optional
 fi

cmd/helm/testdata/output/plugin_echo_bad_directive.txt

@@ -1,6 +0,0 @@
-echo plugin.complete was called
-Namespace: default
-Num args received: 1
-Args received:
-:0
-Completion ended with directive: ShellCompDirectiveDefault