3 files changed, 48 insertions, 3 deletions
diff --git a/rust/src/ast.rs b/rust/src/ast.rs
index 3f8b772..e70f323 100644
--- a/rust/src/ast.rs
+++ b/rust/src/ast.rs
@@ -38,6 +38,10 @@ pub fn identifier() -> RegexGeneratorStrategy<String> {
     string_regex(IDENTIFIER).unwrap()
 }
 
+pub fn ascii_identifier() -> RegexGeneratorStrategy<String> {
+    string_regex("[a-zA-Z][a-zA-Z0-9]*").unwrap()
+}
+
 impl Arbitrary for Value {
     type Parameters = ();
     type Strategy = BoxedStrategy<Self>;
diff --git a/rust/src/lambda.rs b/rust/src/lambda.rs
index 9b7045f..e22d210 100644
--- a/rust/src/lambda.rs
+++ b/rust/src/lambda.rs
@@ -1,5 +1,6 @@
 use proptest::{
     arbitrary::{any, any_with, arbitrary_with},
+    prelude::*,
     strategy::{Strategy, ValueTree},
     test_runner::TestRunner,
 };
@@ -109,11 +110,20 @@ pub fn generate_expr(size: u32, runner: &mut TestRunner) -> Value {
             let n = any::<u16>().new_tree(runner).unwrap().current();
             Value::Num(n.into())
         }
-        2 => Value::Sym(identifier().new_tree(runner).unwrap().current()),
+        2 => Value::Sym(ascii_identifier().new_tree(runner).unwrap().current()),
+        3 => Value::Sym(identifier().new_tree(runner).unwrap().current()),
+        4 => 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];
+    (leaf.clone(), leaf.clone()).prop_map(|(l, r)| Value::App(Box::new(l), Box::new(r)))
+}
+
 #[cfg(test)]
 mod lambda_test {
     use crate::parser::parse;
diff --git a/rust/src/web.rs b/rust/src/web.rs
index 62dea22..af27eda 100644
--- a/rust/src/web.rs
+++ b/rust/src/web.rs
@@ -387,20 +387,51 @@ mod app_tests {
     }
 
     #[test]
-    async fn client_generates_variables_at_level_2() {
+    async fn client_generates_ascii_variables_at_level_2() {
         let mut client = client();
         client.grade = 2;
 
         let (input, _) = client.generate_expr();
 
         let parsed = parse(&input);
-        match parsed[..] {
+        match &parsed[..] {
+            [Value::Sym(name)] => {
+                println!("{}", name);
+                assert!(name.chars().all(|c| c.is_ascii_alphanumeric()));
+            }
+            _ => panic!("Expected symbol, got {:?}", parsed),
+        }
+    }
+
+    #[test]
+    async fn client_generates_unicode_variables_at_level_3() {
+        let mut client = client();
+        client.grade = 3;
+
+        let (input, _) = client.generate_expr();
+
+        let parsed = parse(&input);
+        match &parsed[..] {
             [Value::Sym(_)] => (),
             _ => panic!("Expected symbol, got {:?}", parsed),
         }
     }
 
     #[test]
+    async fn client_generates_binary_application_at_level_4() {
+        let mut client = client();
+        client.grade = 4;
+
+        let (input, _) = client.generate_expr();
+
+        let parsed = parse(&input);
+        match &parsed[..] {
+            [Value::App(_, _)] => (),
+            _ => panic!("Expected symbol, got {:?}", parsed),
+        }
+    }
+
+    #[test]
     async fn client_increases_grade_on_successful_test() {
         let mut client = client();
         let expected = "1".to_string();