Tuple: add tests for deserialization from sequence

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

test_suite/tests/test_enum_adjacently_tagged.rs

@@ -437,11 +437,14 @@ fn newtype_with_newtype() {
     );
 }
 
+mod tuple {
+    use super::*;
+
     #[test]
-fn tuple() {
+    fn map() {
         let value = AdjacentlyTagged::Tuple::<u8>(1, 1);
 
-    // tuple with tag first
+        // Map: tag + content
         assert_tokens(
             &value,
             &[
@@ -463,7 +466,7 @@ fn tuple() {
             ],
         );
 
-    // tuple with content first
+        // Map: content + tag
         assert_de_tokens(
             &value,
             &[
@@ -486,6 +489,29 @@ fn tuple() {
         );
     }
 
+    #[test]
+    fn seq() {
+        let value = AdjacentlyTagged::Tuple::<u8>(1, 1);
+
+        // Seq: tag + content
+        assert_de_tokens(
+            &value,
+            &[
+                Token::Seq { len: Some(2) },
+                Token::UnitVariant {
+                    name: "AdjacentlyTagged",
+                    variant: "Tuple",
+                },
+                Token::Tuple { len: 2 },
+                Token::U8(1),
+                Token::U8(1),
+                Token::TupleEnd,
+                Token::SeqEnd,
+            ],
+        );
+    }
+}
+
 #[test]
 fn struct_() {
     let value = AdjacentlyTagged::Struct::<u8> { f: 1 };