Improve support unit types (#76)

* fix unit type serialization issue

`()` and `A` returned a no key error previously. This is very
unergonimic if you just have a trait bound for Serialize and want to
generate an empty querystring `?`

* add support for deserializing unit structs

* Comment updates for serializer methods

2 files changed, 61 insertions, 0 deletions

diff --git a/tests/test_deserialize.rs b/tests/test_deserialize.rs
index 92e5f53..b2f9dc8 100644
--- a/tests/test_deserialize.rs
+++ b/tests/test_deserialize.rs
@@ -699,3 +699,26 @@ fn deserialize_map_with_int_keys() {
     serde_qs::from_str::<Mapping>("mapping[1]=2&mapping[1]=4")
         .expect_err("should error with repeated key");
 }
+
+#[test]
+fn deserialize_unit_types() {
+    #[derive(Debug, Deserialize, PartialEq)]
+    struct A;
+    #[derive(Debug, Deserialize, PartialEq)]
+    struct B<'a> {
+        t: (),
+        a: &'a str,
+    }
+
+    let test: () = serde_qs::from_str("").unwrap();
+    assert_eq!(test, ());
+
+    let test: A = serde_qs::from_str("").unwrap();
+    assert_eq!(test, A);
+
+    let test: B = serde_qs::from_str("a=test&t=").unwrap();
+    assert_eq!(test, B { t: (), a: "test" });
+
+    let test: B = serde_qs::from_str("t=&a=test").unwrap();
+    assert_eq!(test, B { t: (), a: "test" });
+}
diff --git a/tests/test_serialize.rs b/tests/test_serialize.rs
index b7c4a21..0b9f0c6 100644
--- a/tests/test_serialize.rs
+++ b/tests/test_serialize.rs
@@ -236,3 +236,41 @@ fn test_serializer() {
 
     assert_eq!(writer, b"a[0]=3&a[1]=2&b=a");
 }
+
+#[test]
+fn test_serializer_unit() {
+    use serde::Serialize;
+    #[derive(Serialize)]
+    struct A;
+    #[derive(Serialize)]
+    struct B {
+        t: (),
+    }
+
+    let mut writer = Vec::new();
+    {
+        let serializer = &mut qs::Serializer::new(&mut writer);
+        let q = ();
+        q.serialize(serializer).unwrap();
+    }
+
+    assert_eq!(writer, b"", "we are testing ()");
+    writer.clear();
+
+    {
+        let serializer = &mut qs::Serializer::new(&mut writer);
+        let q = A;
+        q.serialize(serializer).unwrap();
+    }
+
+    assert_eq!(writer, b"", "we are testing A");
+    writer.clear();
+
+    {
+        let serializer = &mut qs::Serializer::new(&mut writer);
+        let q = B { t: () };
+        q.serialize(serializer).unwrap();
+    }
+
+    assert_eq!(writer, b"t=", "we are testing B{{t: ()}}");
+}