2 files changed, 23 insertions, 0 deletions
diff --git a/tvix/eval/src/tests/mod.rs b/tvix/eval/src/tests/mod.rs
index 98c93ba27084..aeec75b2ae9d 100644
--- a/tvix/eval/src/tests/mod.rs
+++ b/tvix/eval/src/tests/mod.rs
@@ -2,6 +2,10 @@ use builtin_macros::builtins;
 use pretty_assertions::assert_eq;
 use test_generator::test_resources;
 
+/// Module for one-off tests which do not follow the rest of the
+/// test layout.
+mod one_offs;
+
 #[builtins]
 mod mock_builtins {
     //! Builtins which are required by language tests, but should not
diff --git a/tvix/eval/src/tests/one_offs.rs b/tvix/eval/src/tests/one_offs.rs
new file mode 100644
index 000000000000..63bb8f7af378
--- /dev/null
+++ b/tvix/eval/src/tests/one_offs.rs
@@ -0,0 +1,19 @@
+use crate::*;
+
+#[test]
+fn test_source_builtin() {
+    // Test an evaluation with a source-only builtin. The test ensures
+    // that the artificially constructed thunking is correct.
+
+    let mut eval = Evaluation::new_impure("builtins.testSourceBuiltin", None);
+    eval.src_builtins.push(("testSourceBuiltin", "42"));
+
+    let result = eval.evaluate();
+    assert!(
+        result.errors.is_empty(),
+        "evaluation failed: {:?}",
+        result.errors
+    );
+
+    assert!(matches!(result.value.unwrap(), Value::Integer(42)));
+}