feat: Automatically dereference pointer types in deepGet

This matches the behavior of Go, and makes it possible to use `groupBy` and
friends on a slice of `*RuntimeContainers`.

Author: rhansen

internal/template/reflect.go

@@ -14,6 +14,13 @@ func deepGetImpl(v reflect.Value, path []string) interface{} {
 	if len(path) == 0 {
 		return v.Interface()
 	}
+	if v.Kind() == reflect.Pointer {
+		v = v.Elem()
+	}
+	if v.Kind() == reflect.Pointer {
+		log.Printf("unable to descend into pointer of a pointer\n")
+		return nil
+	}
 	switch v.Kind() {
 	case reflect.Struct:
 		return deepGetImpl(v.FieldByName(path[0]), path[1:])

internal/template/reflect_test.go

@@ -53,6 +53,9 @@ func TestDeepGetMap(t *testing.T) {
 }
 
 func TestDeepGet(t *testing.T) {
+	s := struct{ X string }{"foo"}
+	sp := &s
+
 	for _, tc := range []struct {
 		desc string
 		item interface{}
@@ -71,6 +74,9 @@ func TestDeepGet(t *testing.T) {
 			"...",
 			"foo",
 		},
+		{"struct", s, "X", "foo"},
+		{"pointer to struct", sp, "X", "foo"},
+		{"double pointer to struct", &sp, ".X", nil},
 	} {
 		t.Run(tc.desc, func(t *testing.T) {
 			got := deepGet(tc.item, tc.path)