fix empty array cornercase

allows empty param if explicit with forced quotes

pkg/summon/run.go

@@ -171,17 +171,20 @@ func (d *Driver) RenderArgs(args ...string) ([]string, error) {
 			continue
 		}
 
-		inner := rt
 		var renderedTargets = []string{rt}
 		if strings.HasPrefix(rt, "[") && strings.HasSuffix(rt, "]") {
-			inner = strings.Trim(rt, "[]")
+			inner := strings.Trim(rt, "[]")
 
 			if inner == "" {
-				renderedTargets = []string{""}
+				continue
 			} else {
-				renderedTargets, err = shlex.Split(inner, true)
-				if err != nil {
-					return nil, err
+				if inner == `""` {
+					renderedTargets = []string{""}
+				} else {
+					renderedTargets, err = shlex.Split(inner, true)
+					if err != nil {
+						return nil, err
+					}
 				}
 			}
 		}

pkg/summon/run_test.go

@@ -296,6 +296,11 @@ func TestFlattenStrings(t *testing.T) {
 			args: []interface{}{},
 			want: []string{},
 		},
+		{
+			name: "empty-slice",
+			args: []interface{}{[]interface{}{}},
+			want: []string{},
+		},
 		{
 			name: "slice-of-slice-of-string",
 			args: []interface{}{[]string{"elem"}},
@@ -620,8 +625,8 @@ func TestFlagUsages(t *testing.T) {
 			expected: []string{"arg"},
 		},
 		{
-			name:     "empty-array-used-to-insert-empty-arg-pos",
-			args:     []string{`[{{flagValue "inexistant"}}]`, "arg"},
+			name:     "empty-array-with-quotes-used-to-insert-empty-arg-pos",
+			args:     []string{`["{{flagValue "inexistant"}}"]`, "arg"},
 			expected: []string{"", "arg"},
 		},
 	}