fix(aiken-lang): assignment as last expr in when and if

crates/aiken-lang/src/tests/check.rs

@@ -204,6 +204,85 @@ fn anonymous_function_dupicate_args() {
     ))
 }
 
+#[test]
+fn assignement_last_expr_when() {
+    let source_code = r#"
+        pub fn foo() {
+          let bar = None
+
+          when bar is {
+            Some(_) -> {
+              let wow = 1
+            }
+            None -> {
+              2
+            }
+          }
+        }
+    "#;
+
+    assert!(matches!(
+        check(parse(source_code)),
+        Err((_, Error::LastExpressionIsAssignment { .. }))
+    ))
+}
+
+#[test]
+fn assignement_last_expr_if_first_branch() {
+    let source_code = r#"
+        pub fn foo() {
+          if True {
+            let thing = 1
+          } else {
+            1
+          }
+        }
+    "#;
+
+    assert!(matches!(
+        check(parse(source_code)),
+        Err((_, Error::LastExpressionIsAssignment { .. }))
+    ))
+}
+
+#[test]
+fn assignement_last_expr_if_branches() {
+    let source_code = r#"
+        pub fn foo() {
+          if True {
+            2
+          } else if False {
+            let thing = 1
+          } else {
+            1
+          }
+        }
+    "#;
+
+    assert!(matches!(
+        check(parse(source_code)),
+        Err((_, Error::LastExpressionIsAssignment { .. }))
+    ))
+}
+
+#[test]
+fn assignement_last_expr_if_final_else() {
+    let source_code = r#"
+        pub fn foo() {
+          if True {
+            1
+          } else {
+            let thing = 1
+          }
+        }
+    "#;
+
+    assert!(matches!(
+        check(parse(source_code)),
+        Err((_, Error::LastExpressionIsAssignment { .. }))
+    ))
+}
+
 #[test]
 fn if_scoping() {
     let source_code = r#"