feat(rslint_parser): check for missing children in parser tests

crates/rslint_parser/src/tests.rs

@@ -6,7 +6,7 @@ use rslint_errors::file::SimpleFile;
 use rslint_errors::termcolor::Buffer;
 use rslint_errors::{file::SimpleFiles, Emitter};
 use rslint_syntax::JsSyntaxKind;
-use std::fmt::Write;
+use std::fmt::Debug;
 use std::panic::catch_unwind;
 use std::path::{Path, PathBuf};
 
@@ -163,11 +163,12 @@ fn has_unknown_nodes(node: &SyntaxNode) -> bool {
         .any(|descendant| descendant.kind().is_unknown())
 }
 
-fn assert_errors_are_absent<T: AstNode>(program: &Parse<T>, path: &Path) {
+fn assert_errors_are_absent<T: AstNode + Debug>(program: &Parse<T>, path: &Path) {
     let syntax = program.syntax();
-    let syntax_errors: Vec<_> = program.tree().missing_children().collect();
+    let debug_tree = format!("{:?}", program.tree());
+    let has_missing_children = debug_tree.contains("missing (required)");
 
-    if !program.has_errors() && !has_unknown_nodes(&syntax) && syntax_errors.is_empty() {
+    if !program.has_errors() && !has_unknown_nodes(&syntax) && has_missing_children {
         return;
     }
 
@@ -179,15 +180,9 @@ fn assert_errors_are_absent<T: AstNode>(program: &Parse<T>, path: &Path) {
         emitter.emit_with_writer(diagnostic, &mut buffer).unwrap();
     }
 
-    let buffer = buffer.into_inner();
-    let mut buffer = String::from_utf8(buffer).unwrap();
-    for syntax_error in syntax_errors {
-        writeln!(buffer, "{}", syntax_error).expect("writing to a String cannot fail");
-    }
-
     panic!("There should be no errors in the file {:?} but the following errors where present:\n{}\n\nParsed tree:\n{:#?}",
         path.display(),
-        buffer,
+        std::str::from_utf8(buffer.as_slice()).unwrap(),
         &syntax
 	);
 }