1 files changed, 29 insertions, 1 deletions
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index 9c78fbc3..22f51d82 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -12,5 +12,33 @@ pub use node::*;
 pub use span::*;
 pub use token::*;
 
-/// A collection of nodes which form a tree together with their children.
+use crate::pretty::{Pretty, Printer};
+
+/// The abstract syntax tree.
 pub type Tree = SpanVec<Node>;
+
+impl Pretty for Tree {
+    fn pretty(&self, p: &mut Printer) {
+        for node in self {
+            node.v.pretty(p);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::parse::parse;
+    use crate::pretty::pretty;
+
+    #[track_caller]
+    pub fn test_pretty(src: &str, exp: &str) {
+        let tree = parse(src).output;
+        let found = pretty(&tree);
+        if exp != found {
+            println!("tree:     {:#?}", tree);
+            println!("expected: {}", exp);
+            println!("found:    {}", found);
+            panic!("test failed");
+        }
+    }
+}