Newtype: add tests for deserialization from sequence

(review this commit with "ignore whitespace changes" option on)

test_suite/tests/test_enum_adjacently_tagged.rs

@@ -302,11 +302,14 @@ mod unit {
     }
 }
 
+mod newtype {
+    use super::*;
+
     #[test]
-fn newtype() {
+    fn map_tag_content() {
         let value = AdjacentlyTagged::Newtype::<u8>(1);
 
-    // newtype with tag first
+        // Map: tag + content
         assert_tokens(
             &value,
             &[
@@ -325,7 +328,7 @@ fn newtype() {
             ],
         );
 
-    // newtype with content first
+        // Map: content + tag
         assert_de_tokens(
             &value,
             &[
@@ -343,7 +346,10 @@ fn newtype() {
                 Token::StructEnd,
             ],
         );
+    }
 
+    #[test]
+    fn map_tag_only() {
         // optional newtype with no content field
         assert_de_tokens(
             &AdjacentlyTagged::Newtype::<Option<u8>>(None),
@@ -362,6 +368,48 @@ fn newtype() {
         );
     }
 
+    #[test]
+    fn seq() {
+        let value = AdjacentlyTagged::Newtype::<u8>(1);
+
+        // Seq: tag and content
+        assert_de_tokens(
+            &value,
+            &[
+                Token::Seq { len: Some(2) },
+                Token::UnitVariant {
+                    name: "AdjacentlyTagged",
+                    variant: "Newtype",
+                },
+                Token::U8(1),
+                Token::SeqEnd,
+            ],
+        );
+
+        // Seq: tag (as string) and content
+        assert_de_tokens(
+            &value,
+            &[
+                Token::Seq { len: None },
+                Token::Str("Newtype"), // tag
+                Token::U8(1),          // content
+                Token::SeqEnd,
+            ],
+        );
+
+        // Seq: tag (as borrowed string) and content
+        assert_de_tokens(
+            &value,
+            &[
+                Token::Seq { len: None },
+                Token::BorrowedStr("Newtype"), // tag
+                Token::U8(1),                  // content
+                Token::SeqEnd,
+            ],
+        );
+    }
+}
+
 #[test]
 fn newtype_with_newtype() {
     #[derive(Debug, PartialEq, Serialize, Deserialize)]