Proptest testing!

src/syntax.rs

@@ -2,6 +2,7 @@ use codespan_reporting::{diagnostic::Diagnostic, files::SimpleFiles};
 use lalrpop_util::lalrpop_mod;
 use logos::Logos;
 
+mod arbitrary;
 pub mod ast;
 mod location;
 mod simplify;
@@ -18,8 +19,12 @@ pub use crate::syntax::ast::*;
 pub use crate::syntax::location::Location;
 use crate::syntax::parser::ProgramParser;
 pub use crate::syntax::tokens::{LexerError, Token};
+#[cfg(test)]
+use ::pretty::{Arena, Pretty};
 use lalrpop_util::ParseError;
 #[cfg(test)]
+use proptest::{prop_assert, prop_assert_eq};
+#[cfg(test)]
 use std::str::FromStr;
 use thiserror::Error;
 
@@ -236,3 +241,32 @@ fn order_of_operations() {
         }
     );
 }
+
+proptest::proptest! {
+    #[test]
+    fn random_render_parses_equal(program: Program) {
+        let mut file_database = SimpleFiles::new();
+        let writer = ::pretty::termcolor::StandardStream::stderr(::pretty::termcolor::ColorChoice::Auto);
+        let config = codespan_reporting::term::Config::default();
+        let allocator = Arena::<()>::new();
+
+        let mut out_vector = vec![];
+        prop_assert!(program.pretty(&allocator).render(80, &mut out_vector).is_ok());
+        let string = std::str::from_utf8(&out_vector).expect("emitted valid string");
+        let file_handle = file_database.add("test", string);
+        let file_db_info = file_database.get(file_handle).expect("find thing just inserted");
+        let parsed = Program::parse(file_handle, file_db_info.source());
+
+        if let Err(e) = &parsed {
+            eprintln!("failed to parse:\n{}", string);
+            codespan_reporting::term::emit(&mut writer.lock(), &config, &file_database, &e.into()).unwrap();
+        }
+        prop_assert_eq!(program, parsed.unwrap());
+     }
+
+     #[test]
+     fn random_syntaxes_validate(program: Program) {
+        let (errors, _) = program.validate();
+        prop_assert!(errors.is_empty());
+     }
+}