Add test for #18 (missing constructed bit when serializing [2] IMPLICIT)

tests/issue-18-constructed-bit-sequence.rs

@@ -0,0 +1,26 @@
+#![cfg(feature = "std")]
+
+use std::borrow::Cow;
+
+use asn1_rs::*;
+
+#[derive(DerSequence, Debug, PartialEq)]
+struct Person {
+    name: String,
+    age: u16,
+}
+
+#[test]
+fn issue_18_1() {
+    // create a sequence from random data
+    let seq = Sequence::new(Cow::Borrowed(&[2, 2, 18, 52, 2, 2, 86, 12]));
+
+    // now serialize a [2] IMPLICIT Person
+    type T2<'a> = TaggedValue<Sequence<'a>, Error, Implicit, { Class::UNIVERSAL }, 2>;
+    let tagged = T2::implicit(seq);
+
+    let result = tagged.to_der_vec().expect("Could not serialize sequence");
+
+    let (_, header) = Header::from_der(&result).expect("could not parse serialized data");
+    assert!(header.is_constructed());
+}