1 files changed, 105 insertions, 0 deletions
diff --git a/tests/comments.rs b/tests/comments.rs
new file mode 100644
index 0000000..4f7236d
--- /dev/null
+++ b/tests/comments.rs
@@ -0,0 +1,105 @@
+#![allow(clippy::assertions_on_result_states)]
+
+use proc_macro2::{Delimiter, Literal, Spacing, TokenStream, TokenTree};
+
+// #[doc = "..."] -> "..."
+fn lit_of_outer_doc_comment(tokens: &TokenStream) -> Literal {
+    lit_of_doc_comment(tokens, false)
+}
+
+// #![doc = "..."] -> "..."
+fn lit_of_inner_doc_comment(tokens: &TokenStream) -> Literal {
+    lit_of_doc_comment(tokens, true)
+}
+
+fn lit_of_doc_comment(tokens: &TokenStream, inner: bool) -> Literal {
+    let mut iter = tokens.clone().into_iter();
+    match iter.next().unwrap() {
+        TokenTree::Punct(punct) => {
+            assert_eq!(punct.as_char(), '#');
+            assert_eq!(punct.spacing(), Spacing::Alone);
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    if inner {
+        match iter.next().unwrap() {
+            TokenTree::Punct(punct) => {
+                assert_eq!(punct.as_char(), '!');
+                assert_eq!(punct.spacing(), Spacing::Alone);
+            }
+            _ => panic!("wrong token {:?}", tokens),
+        }
+    }
+    iter = match iter.next().unwrap() {
+        TokenTree::Group(group) => {
+            assert_eq!(group.delimiter(), Delimiter::Bracket);
+            assert!(iter.next().is_none(), "unexpected token {:?}", tokens);
+            group.stream().into_iter()
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    };
+    match iter.next().unwrap() {
+        TokenTree::Ident(ident) => assert_eq!(ident.to_string(), "doc"),
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    match iter.next().unwrap() {
+        TokenTree::Punct(punct) => {
+            assert_eq!(punct.as_char(), '=');
+            assert_eq!(punct.spacing(), Spacing::Alone);
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    match iter.next().unwrap() {
+        TokenTree::Literal(literal) => {
+            assert!(iter.next().is_none(), "unexpected token {:?}", tokens);
+            literal
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+}
+
+#[test]
+fn closed_immediately() {
+    let stream = "/**/".parse::<TokenStream>().unwrap();
+    let tokens = stream.into_iter().collect::<Vec<_>>();
+    assert!(tokens.is_empty(), "not empty -- {:?}", tokens);
+}
+
+#[test]
+fn incomplete() {
+    assert!("/*/".parse::<TokenStream>().is_err());
+}
+
+#[test]
+fn lit() {
+    let stream = "/// doc".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\" doc\"");
+
+    let stream = "//! doc".parse::<TokenStream>().unwrap();
+    let lit = lit_of_inner_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\" doc\"");
+
+    let stream = "/** doc */".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\" doc \"");
+
+    let stream = "/*! doc */".parse::<TokenStream>().unwrap();
+    let lit = lit_of_inner_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\" doc \"");
+}
+
+#[test]
+fn carriage_return() {
+    let stream = "///\r\n".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\"\"");
+
+    let stream = "/**\r\n*/".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(&stream);
+    assert_eq!(lit.to_string(), "\"\\r\\n\"");
+
+    "///\r".parse::<TokenStream>().unwrap_err();
+    "///\r \n".parse::<TokenStream>().unwrap_err();
+    "/**\r \n*/".parse::<TokenStream>().unwrap_err();
+}