Rollup merge of #151384 - pm-tokenstream-tests, r=Kivooeo

add basic `TokenStream` api tests

There were none so far. Especially helpful for #130856.

Author: Zalathar

tests/ui/proc-macro/auxiliary/api/proc_macro_api_tests.rs

@@ -8,6 +8,7 @@ extern crate proc_macro;
 mod cmp;
 mod ident;
 mod literal;
+mod tokenstream;
 
 use proc_macro::TokenStream;
 
@@ -18,6 +19,7 @@ pub fn run(input: TokenStream) -> TokenStream {
     cmp::test();
     ident::test();
     literal::test();
+    tokenstream::test();
 
     TokenStream::new()
 }

tests/ui/proc-macro/auxiliary/api/tokenstream.rs

@@ -0,0 +1,28 @@
+use proc_macro::*;
+
+fn assert_eq(l: TokenStream, r: TokenStream) {
+    assert_eq!(l.to_string(), r.to_string());
+    for (lt, rt) in l.into_iter().zip(r) {
+        assert_eq!(lt.to_string(), rt.to_string());
+    }
+}
+
+pub fn test() {
+    assert_eq(TokenStream::new(), TokenStream::new());
+    let mut stream = TokenStream::new();
+    assert!(stream.is_empty());
+    stream.extend(TokenStream::new());
+    assert_eq(stream.clone(), TokenStream::new());
+
+    let old = stream.clone();
+    stream.extend(vec![TokenTree::Ident(Ident::new("foo", Span::call_site()))]);
+    assert!(!stream.is_empty());
+    assert!(old.is_empty());
+
+    let stream2 = stream
+        .clone()
+        .into_iter()
+        .inspect(|tree| assert_eq!(tree.to_string(), "foo"))
+        .collect::<TokenStream>();
+    assert_eq(stream.clone(), stream2);
+}