Allow trailing commas in inline snapshots (#472)

cargo-insta/src/inline.rs

@@ -171,6 +171,14 @@ impl FilePatcher {
             }
 
             fn try_extract_snapshot(&mut self, tokens: &[TokenTree], indentation: usize) -> bool {
+                // ignore optional trailing comma
+                let tokens = match tokens.last() {
+                    Some(TokenTree::Punct(ref punct)) if punct.as_char() == ',' => {
+                        &tokens[..tokens.len() - 1]
+                    }
+                    _ => tokens,
+                };
+
                 if tokens.len() < 2 {
                     return false;
                 }

cargo-insta/tests/snapshots/main__test_basic_utf8_inline.snap

@@ -1,7 +1,6 @@
 ---
-source: src/main.rs
+source: cargo-insta/tests/main.rs
 expression: "&fs::read_to_string(gen_file).unwrap()"
-input_file: tests/test_basic_utf8_inline.rs
 ---
 #[test]
 #[rustfmt::skip]
@@ -22,3 +21,10 @@ fn test_remove_existing_value_multiline() {
     );
 }
 
+#[test]
+fn test_trailing_comma_in_inline_snapshot() {
+    insta::assert_snapshot!(
+        "new value",
+        @"new value",  // comma here
+    );
+}

cargo-insta/tests/snapshots/main__test_json_inline.snap

@@ -1,7 +1,6 @@
 ---
-source: src/main.rs
+source: cargo-insta/tests/main.rs
 expression: "&fs::read_to_string(gen_file).unwrap()"
-input_file: tests/test_json_inline.rs
 ---
 use serde::Serialize;
 
@@ -27,3 +26,34 @@ fn test_json_snapshot() {
     "###);
 }
 
+#[test]
+fn test_json_snapshot_trailing_comma() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_compact_json_snapshot!(
+        &user,
+        @r###"{"id": 42, "email": "john.doe@example.com"}"###,
+    );
+}
+
+#[test]
+fn test_json_snapshot_trailing_comma_redaction() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_json_snapshot!(
+        &user,
+        {
+            ".id" => "[user_id]",
+        },
+        @r###"
+    {
+      "id": "[user_id]",
+      "email": "[email protected]"
+    }
+    "###,
+    );
+}

cargo-insta/tests/snapshots/main__test_yaml_inline.snap

@@ -1,7 +1,6 @@
 ---
-source: src/main.rs
+source: cargo-insta/tests/main.rs
 expression: "&fs::read_to_string(gen_file).unwrap()"
-input_file: tests/test_yaml_inline.rs
 ---
 use serde::Serialize;
 
@@ -26,3 +25,21 @@ fn test_yaml_snapshot() {
     "###);
 }
 
+#[test]
+fn test_yaml_snapshot_trailing_comma() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_yaml_snapshot!(
+        &user,
+        {
+            ".id" => "[user_id]",
+        },
+        @r###"
+    ---
+    id: "[user_id]"
+    email: john.doe@example.com
+    "###,
+    );
+}

cargo-insta/tests/test-input/test_basic_utf8_inline.rs

@@ -18,3 +18,11 @@ fn test_remove_existing_value_multiline() {
         it really is"
     );
 }
+
+#[test]
+fn test_trailing_comma_in_inline_snapshot() {
+    insta::assert_snapshot!(
+        "new value",
+        @"old value",  // comma here
+    );
+}

cargo-insta/tests/test-input/test_json_inline.rs

@@ -16,3 +16,30 @@ fn test_json_snapshot() {
         ".id" => "[user_id]",
     }, @"");
 }
+
+#[test]
+fn test_json_snapshot_trailing_comma() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_compact_json_snapshot!(
+        &user,
+        @"",
+    );
+}
+
+#[test]
+fn test_json_snapshot_trailing_comma_redaction() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_json_snapshot!(
+        &user,
+        {
+            ".id" => "[user_id]",
+        },
+        @"",
+    );
+}

cargo-insta/tests/test-input/test_yaml_inline.rs

@@ -16,3 +16,18 @@ fn test_yaml_snapshot() {
         ".id" => "[user_id]",
     }, @"");
 }
+
+#[test]
+fn test_yaml_snapshot_trailing_comma() {
+    let user = User {
+        id: 42,
+        email: "[email protected]".into(),
+    };
+    insta::assert_yaml_snapshot!(
+        &user,
+        {
+            ".id" => "[user_id]",
+        },
+        @"",
+    );
+}

insta/src/macros.rs

@@ -219,7 +219,7 @@ macro_rules! assert_compact_json_snapshot {
     };
 }
 
-// The macro handles optional trailing commas for file snapshots.
+// This macro handles optional trailing commas.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! _assert_serialized_snapshot {
@@ -228,8 +228,7 @@ macro_rules! _assert_serialized_snapshot {
     //
     // Note that if we could unify the Inline & File representations of snapshots
     // redactions we could unify some of these branches.
-
-    (format=$format:ident, $value:expr, $(match ..)? {$($k:expr => $v:expr),* $(,)?}, @$snapshot:literal) => {{
+    (format=$format:ident, $value:expr, $(match ..)? {$($k:expr => $v:expr),* $(,)?}, @$snapshot:literal $(,)?) => {{
         let transform = |value| {
             let (_, value) = $crate::_prepare_snapshot_for_redaction!(value, {$($k => $v),*}, $format, Inline);
             value
@@ -250,8 +249,7 @@ macro_rules! _assert_serialized_snapshot {
     }};
     // If there's an inline snapshot, capture serialization function and pass to
     // `_assert_snapshot_base`, specifying `Inline`
-    //
-    (format=$format:ident, $($arg:expr),*, @$snapshot:literal) => {{
+    (format=$format:ident, $($arg:expr),*, @$snapshot:literal $(,)?) => {{
         let transform = |value| {$crate::_macro_support::serialize_value(
             &value,
             $crate::_macro_support::SerializationFormat::$format,
@@ -321,7 +319,7 @@ macro_rules! assert_debug_snapshot {
 // the value. This allows us to implement other macros with a small wrapper. All
 // snapshot macros eventually call this macro.
 //
-// The macro handles optional trailing commas in file snapshots.
+// This macro handles optional trailing commas.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! _assert_snapshot_base {

insta/tests/test_inline.rs

@@ -24,6 +24,14 @@ fn test_simple() {
     "###);
 }
 
+#[test]
+fn test_trailing_commas() {
+    assert_snapshot!(
+        "Testing",
+        @"Testing",
+    );
+}
+
 #[test]
 fn test_single_line() {
     assert_snapshot!("Testing", @"Testing");

insta/tests/test_redaction.rs

@@ -111,6 +111,24 @@ fn test_with_random_value_and_match_comma() {
             ".id" => "[id]",
         }, // comma here
     );
+    assert_yaml_snapshot!(
+        &User {
+            id: 11,
+            username: "john_doe".to_string(),
+            email: Email("[email protected]".to_string()),
+            extra: "".to_string(),
+        },
+        match .. {
+            ".id" => "[id]",
+        },
+        @r###"
+        ---
+        id: "[id]"
+        username: john_doe
+        email: [email protected]
+        extra: ""
+        "###, // comma here
+    );
 }
 
 #[cfg(feature = "csv")]