Unit: add tests for deserialization from sequence

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

test_suite/tests/test_enum_adjacently_tagged.rs

@@ -18,9 +18,12 @@ enum AdjacentlyTagged<T> {
     Struct { f: u8 },
 }
 
+mod unit {
+    use super::*;
+
     #[test]
-fn unit() {
+    fn map_str_tag_only() {
-    // unit with no content
+        // Map: tag only
         assert_tokens(
             &AdjacentlyTagged::Unit::<u8>,
             &[
@@ -37,7 +40,7 @@ fn unit() {
             ],
         );
 
-    // unit with no content and incorrect hint for number of elements
+        // Map: tag only and incorrect hint for number of elements
         assert_de_tokens(
             &AdjacentlyTagged::Unit::<u8>,
             &[
@@ -53,8 +56,11 @@ fn unit() {
                 Token::StructEnd,
             ],
         );
+    }
 
-    // unit with tag first
+    #[test]
+    fn map_str_tag_content() {
+        // Map: tag + content
         assert_de_tokens(
             &AdjacentlyTagged::Unit::<u8>,
             &[
@@ -72,8 +78,7 @@ fn unit() {
                 Token::StructEnd,
             ],
         );
-
+        // Map: content + tag
-    // unit with content first
         assert_de_tokens(
             &AdjacentlyTagged::Unit::<u8>,
             &[
@@ -92,7 +97,7 @@ fn unit() {
             ],
         );
 
-    // unit with excess content (f, g, h)
+        // Map: tag + content + excess fields (f, g, h)
         assert_de_tokens(
             &AdjacentlyTagged::Unit::<u8>,
             &[
@@ -118,6 +123,46 @@ fn unit() {
         );
     }
 
+    #[test]
+    fn seq_tag_content() {
+        // Seq: tag and content
+        assert_de_tokens(
+            &AdjacentlyTagged::Unit::<u8>,
+            &[
+                Token::Seq { len: Some(2) },
+                Token::UnitVariant {
+                    name: "AdjacentlyTagged",
+                    variant: "Unit",
+                },
+                Token::Unit,
+                Token::SeqEnd,
+            ],
+        );
+
+        // Seq: tag (as string) and content
+        assert_de_tokens(
+            &AdjacentlyTagged::Unit::<u8>,
+            &[
+                Token::Seq { len: None },
+                Token::Str("Unit"), // tag
+                Token::Unit,        // content
+                Token::SeqEnd,
+            ],
+        );
+
+        // Seq: tag (as borrowed string) and content
+        assert_de_tokens(
+            &AdjacentlyTagged::Unit::<u8>,
+            &[
+                Token::Seq { len: None },
+                Token::BorrowedStr("Unit"), // tag
+                Token::Unit,                // content
+                Token::SeqEnd,
+            ],
+        );
+    }
+}
+
 #[test]
 fn newtype() {
     let value = AdjacentlyTagged::Newtype::<u8>(1);