From e8ab131a2b54aa4252ccda3261a0a6a2ade6a273 Mon Sep 17 00:00:00 2001
From: Arnaud Bailly <arnaud.bailly@iohk.io>
Date: Tue, 8 Oct 2024 22:32:44 +0200
Subject: Generate nested binary applications

Also factor out common strategies into functions
---
 rust/src/lambda.rs | 22 ++++++++++++++++++----
 rust/src/web.rs    | 16 ++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/rust/src/lambda.rs b/rust/src/lambda.rs
index e22d210..406aebf 100644
--- a/rust/src/lambda.rs
+++ b/rust/src/lambda.rs
@@ -111,19 +111,33 @@ pub fn generate_expr(size: u32, runner: &mut TestRunner) -> Value {
             Value::Num(n.into())
         }
         2 => Value::Sym(ascii_identifier().new_tree(runner).unwrap().current()),
-        3 => Value::Sym(identifier().new_tree(runner).unwrap().current()),
+        3 => any_sym().new_tree(runner).unwrap().current(),
         4 => simple_app().new_tree(runner).unwrap().current(),
+        5 => nested_simple_app().new_tree(runner).unwrap().current(),
         _ => todo!(),
     }
 }
 
 fn simple_app() -> impl Strategy<Value = Value> {
-    let any_num = any::<i32>().prop_map(Value::Num);
-    let any_sym = identifier().prop_map(Value::Sym);
-    let leaf = prop_oneof![any_num, any_sym];
+    let leaf = prop_oneof![any_num(), any_sym()];
     (leaf.clone(), leaf.clone()).prop_map(|(l, r)| Value::App(Box::new(l), Box::new(r)))
 }
 
+fn any_num() -> impl Strategy<Value = Value> {
+    any::<i32>().prop_map(Value::Num)
+}
+
+fn nested_simple_app() -> impl Strategy<Value = Value> {
+    let leaf = prop_oneof![any_num(), any_sym()];
+    leaf.prop_recursive(4, 128, 5, move |inner| {
+        (inner.clone(), inner.clone()).prop_map(|(l, r)| Value::App(Box::new(l), Box::new(r)))
+    })
+}
+
+fn any_sym() -> impl Strategy<Value = Value> {
+    identifier().prop_map(Value::Sym)
+}
+
 #[cfg(test)]
 mod lambda_test {
     use crate::parser::parse;
diff --git a/rust/src/web.rs b/rust/src/web.rs
index af27eda..3d9fcda 100644
--- a/rust/src/web.rs
+++ b/rust/src/web.rs
@@ -431,6 +431,22 @@ mod app_tests {
         }
     }
 
+    #[test]
+    async fn client_generates_nested_applications_and_constants_at_level_5() {
+        let mut client = client();
+        client.grade = 5;
+
+        let (input, _) = client.generate_expr();
+
+        let parsed = parse(&input);
+        match &parsed[..] {
+            [Value::App(_, _)] => (),
+            [Value::Sym(_)] => (),
+            [Value::Num(_)] => (),
+            _ => panic!("Expected symbol, got {:?}", parsed),
+        }
+    }
+
     #[test]
     async fn client_increases_grade_on_successful_test() {
         let mut client = client();
-- 
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