From ec8517b33c137c48c38b74ba5be21815763a50f5 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 24 Dec 2023 19:31:22 -0800
Subject: [PATCH] Add tuple comma tests

---
 tests/test_expr.rs | 59 ++++++++++++++++++++++++++++++++++++++++++++--
 tests/test_pat.rs  | 56 +++++++++++++++++++++++++++++++++++++++++--
 tests/test_ty.rs   | 58 +++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 167 insertions(+), 6 deletions(-)

diff --git a/tests/test_expr.rs b/tests/test_expr.rs
index fef2e9b95d..daf0d63c3b 100644
--- a/tests/test_expr.rs
+++ b/tests/test_expr.rs
@@ -4,8 +4,9 @@
 mod macros;
 
 use proc_macro2::{Delimiter, Group};
-use quote::quote;
-use syn::{Expr, ExprRange, Stmt};
+use quote::{quote, ToTokens as _};
+use syn::punctuated::Punctuated;
+use syn::{parse_quote, token, Expr, ExprRange, ExprTuple, Stmt, Token};
 
 #[test]
 fn test_expr_parse() {
@@ -483,3 +484,57 @@ fn test_extended_interpolated_path() {
     }
     "###);
 }
+
+#[test]
+fn test_tuple_comma() {
+    let mut expr = ExprTuple {
+        attrs: Vec::new(),
+        paren_token: token::Paren::default(),
+        elems: Punctuated::new(),
+    };
+    snapshot!(expr.to_token_stream() as Expr, @"Expr::Tuple");
+
+    expr.elems.push_value(parse_quote!(continue));
+    // Must not parse to Expr::Paren
+    snapshot!(expr.to_token_stream() as Expr, @r###"
+    Expr::Tuple {
+        elems: [
+            Expr::Continue,
+            Token![,],
+        ],
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Expr, @r###"
+    Expr::Tuple {
+        elems: [
+            Expr::Continue,
+            Token![,],
+        ],
+    }
+    "###);
+
+    expr.elems.push_value(parse_quote!(continue));
+    snapshot!(expr.to_token_stream() as Expr, @r###"
+    Expr::Tuple {
+        elems: [
+            Expr::Continue,
+            Token![,],
+            Expr::Continue,
+        ],
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Expr, @r###"
+    Expr::Tuple {
+        elems: [
+            Expr::Continue,
+            Token![,],
+            Expr::Continue,
+            Token![,],
+        ],
+    }
+    "###);
+}
diff --git a/tests/test_pat.rs b/tests/test_pat.rs
index cab7aa7f6d..89033083c3 100644
--- a/tests/test_pat.rs
+++ b/tests/test_pat.rs
@@ -4,9 +4,10 @@
 mod macros;
 
 use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
-use quote::quote;
+use quote::{quote, ToTokens as _};
 use syn::parse::Parser;
-use syn::{Item, Pat, Stmt};
+use syn::punctuated::Punctuated;
+use syn::{parse_quote, token, Item, Pat, PatTuple, Stmt, Token};
 
 #[test]
 fn test_pat_ident() {
@@ -95,3 +96,54 @@ fn test_ranges() {
     Pat::parse_single.parse_str("[_, (..=hi), _]").unwrap();
     Pat::parse_single.parse_str("[_, lo..=hi, _]").unwrap();
 }
+
+#[test]
+fn test_tuple_comma() {
+    let mut expr = PatTuple {
+        attrs: Vec::new(),
+        paren_token: token::Paren::default(),
+        elems: Punctuated::new(),
+    };
+    snapshot!(expr.to_token_stream() as Pat, @"Pat::Tuple");
+
+    expr.elems.push_value(parse_quote!(_));
+    // FIXME: must parse to Pat::Tuple, not Pat::Paren
+    snapshot!(expr.to_token_stream() as Pat, @r###"
+    Pat::Paren {
+        pat: Pat::Wild,
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Pat, @r###"
+    Pat::Tuple {
+        elems: [
+            Pat::Wild,
+            Token![,],
+        ],
+    }
+    "###);
+
+    expr.elems.push_value(parse_quote!(_));
+    snapshot!(expr.to_token_stream() as Pat, @r###"
+    Pat::Tuple {
+        elems: [
+            Pat::Wild,
+            Token![,],
+            Pat::Wild,
+        ],
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Pat, @r###"
+    Pat::Tuple {
+        elems: [
+            Pat::Wild,
+            Token![,],
+            Pat::Wild,
+            Token![,],
+        ],
+    }
+    "###);
+}
diff --git a/tests/test_ty.rs b/tests/test_ty.rs
index 16f2665d03..06453934f8 100644
--- a/tests/test_ty.rs
+++ b/tests/test_ty.rs
@@ -4,8 +4,9 @@
 mod macros;
 
 use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
-use quote::quote;
-use syn::Type;
+use quote::{quote, ToTokens as _};
+use syn::punctuated::Punctuated;
+use syn::{parse_quote, token, Token, Type, TypeTuple};
 
 #[test]
 fn test_mut_self() {
@@ -341,3 +342,56 @@ fn test_trailing_plus() {
     }
     "###);
 }
+
+#[test]
+fn test_tuple_comma() {
+    let mut expr = TypeTuple {
+        paren_token: token::Paren::default(),
+        elems: Punctuated::new(),
+    };
+    snapshot!(expr.to_token_stream() as Type, @"Type::Tuple");
+
+    expr.elems.push_value(parse_quote!(_));
+    // Must not parse to Type::Paren
+    snapshot!(expr.to_token_stream() as Type, @r###"
+    Type::Tuple {
+        elems: [
+            Type::Infer,
+            Token![,],
+        ],
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Type, @r###"
+    Type::Tuple {
+        elems: [
+            Type::Infer,
+            Token![,],
+        ],
+    }
+    "###);
+
+    expr.elems.push_value(parse_quote!(_));
+    snapshot!(expr.to_token_stream() as Type, @r###"
+    Type::Tuple {
+        elems: [
+            Type::Infer,
+            Token![,],
+            Type::Infer,
+        ],
+    }
+    "###);
+
+    expr.elems.push_punct(<Token![,]>::default());
+    snapshot!(expr.to_token_stream() as Type, @r###"
+    Type::Tuple {
+        elems: [
+            Type::Infer,
+            Token![,],
+            Type::Infer,
+            Token![,],
+        ],
+    }
+    "###);
+}