Add additional checks for unit and newtype_unit tests

- check that unit variant can be deserialized from a map
- check that newtype variant with unit can be deserialized from a struct

Author: Mingun

test_suite/tests/test_enum_internally_tagged.rs

@@ -73,6 +73,25 @@ fn unit() {
         ],
     );
 
+    assert_de_tokens(
+        &InternallyTagged::Unit,
+        &[
+            Token::Map { len: Some(1) },
+            Token::Str("tag"),
+            Token::Str("Unit"),
+            Token::MapEnd,
+        ],
+    );
+    assert_de_tokens(
+        &InternallyTagged::Unit,
+        &[
+            Token::Map { len: Some(1) },
+            Token::BorrowedStr("tag"),
+            Token::BorrowedStr("Unit"),
+            Token::MapEnd,
+        ],
+    );
+
     assert_de_tokens(
         &InternallyTagged::Unit,
         &[
@@ -113,6 +132,31 @@ fn newtype_unit() {
             Token::MapEnd,
         ],
     );
+
+    assert_de_tokens(
+        &value,
+        &[
+            Token::Struct {
+                name: "InternallyTagged",
+                len: 1,
+            },
+            Token::Str("tag"),
+            Token::Str("NewtypeUnit"),
+            Token::StructEnd,
+        ],
+    );
+    assert_de_tokens(
+        &value,
+        &[
+            Token::Struct {
+                name: "InternallyTagged",
+                len: 1,
+            },
+            Token::BorrowedStr("tag"),
+            Token::BorrowedStr("NewtypeUnit"),
+            Token::StructEnd,
+        ],
+    );
 }
 
 #[test]