json-pawarser: make return of object grammar easier to understand

crates/json-pawarser/src/grammar.rs

@@ -1,10 +1,17 @@
 use array::array;
 use enumset::{enum_set, EnumSet};
+use pawarser::parser::ParserBuilder;
 
-use crate::{syntax_error::SyntaxError, syntax_kind::SyntaxKind};
+use crate::{
+    syntax_error::SyntaxError,
+    syntax_kind::{lex, SyntaxKind},
+};
 
 use self::object::object;
 
+mod array;
+mod object;
+
 pub(crate) type Parser<'src> = pawarser::Parser<'src, SyntaxKind, SyntaxError>;
 pub(crate) type CompletedMarker = pawarser::CompletedMarker<SyntaxKind, SyntaxError>;
 
@@ -20,5 +27,52 @@ pub fn value(p: &mut Parser) -> bool {
     }
 }
 
-mod array;
-mod object;
+#[cfg(test)]
+mod tests {
+    use super::{
+        test_utils::{check_parser, gen_checks},
+        value,
+    };
+
+    #[test]
+    fn value_lit() {
+        gen_checks! {value;
+            r#""helo world""# => r#"ROOT { STRING "\"helo world\""; }"#,
+            "42" => r#"ROOT { NUMBER "42"; }"#,
+            "null" => r#"ROOT { NULL "null"; }"#,
+            "true" => r#"ROOT { BOOL "true"; }"#,
+            "false" => r#"ROOT { BOOL "false"; }"#
+        };
+    }
+}
+
+#[cfg(test)]
+mod test_utils {
+    use pawarser::parser::ParserBuilder;
+
+    use crate::syntax_kind::{lex, SyntaxKind};
+
+    use super::Parser;
+
+    macro_rules! gen_checks {
+        ($fn_to_test:ident; $($in:literal => $out:literal),+) => {
+            $(crate::grammar::test_utils::check_parser($in, |p| { $fn_to_test(p); }, $out);)+
+        }
+    }
+
+    pub(super) use gen_checks;
+
+    pub(super) fn check_parser(input: &str, parser_fn: fn(&mut Parser), expected_output: &str) {
+        let toks = lex(input);
+        let mut p: Parser = ParserBuilder::new(toks)
+            .add_meaningless(SyntaxKind::WHITESPACE)
+            .add_meaningless(SyntaxKind::NEWLINE)
+            .build();
+
+        parser_fn(&mut p);
+
+        let out = p.finish();
+
+        assert_eq!(format!("{out:?}").trim_end(), expected_output);
+    }
+}

crates/json-pawarser/src/grammar/object.rs

@@ -23,10 +23,10 @@ pub(super) fn object(p: &mut Parser) -> Option<CompletedMarker> {
         }
     }
 
-    Some(if !p.eat(SyntaxKind::BRACE_CLOSE) {
-        obj_start.error(p, SyntaxError::UnclosedObject)
-    } else {
+    Some(if p.eat(SyntaxKind::BRACE_CLOSE) {
         obj_start.complete(p, SyntaxKind::OBJECT)
+    } else {
+        obj_start.error(p, SyntaxError::UnclosedObject)
     })
 }