1 files changed, 106 insertions, 0 deletions
diff --git a/tvix/eval/src/value/arbitrary.rs b/tvix/eval/src/value/arbitrary.rs
new file mode 100644
index 000000000000..bf53f4fcb28a
--- /dev/null
+++ b/tvix/eval/src/value/arbitrary.rs
@@ -0,0 +1,106 @@
+//! Support for configurable generation of arbitrary nix values
+
+use imbl::proptest::{ord_map, vector};
+use proptest::{prelude::*, strategy::BoxedStrategy};
+use std::ffi::OsString;
+
+use super::{attrs::AttrsRep, NixAttrs, NixList, NixString, Value};
+
+#[derive(Clone)]
+pub enum Parameters {
+    Strategy(BoxedStrategy<Value>),
+    Parameters {
+        generate_internal_values: bool,
+        generate_functions: bool,
+        generate_nested: bool,
+    },
+}
+
+impl Default for Parameters {
+    fn default() -> Self {
+        Self::Parameters {
+            generate_internal_values: false,
+            generate_functions: false,
+            generate_nested: true,
+        }
+    }
+}
+
+impl Arbitrary for NixAttrs {
+    type Parameters = Parameters;
+    type Strategy = BoxedStrategy<Self>;
+
+    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
+        prop_oneof![
+            // Empty attrs representation
+            Just(Self(AttrsRep::Empty)),
+            // KV representation (name/value pairs)
+            (
+                any_with::<Value>(args.clone()),
+                any_with::<Value>(args.clone())
+            )
+                .prop_map(|(name, value)| Self(AttrsRep::KV { name, value })),
+            // Map representation
+            ord_map(NixString::arbitrary(), Value::arbitrary_with(args), 0..100)
+                .prop_map(|map| Self(AttrsRep::Im(map)))
+        ]
+        .boxed()
+    }
+}
+
+impl Arbitrary for NixList {
+    type Parameters = <Value as Arbitrary>::Parameters;
+    type Strategy = BoxedStrategy<Self>;
+
+    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
+        vector(<Value as Arbitrary>::arbitrary_with(args), 0..100)
+            .prop_map(NixList::from)
+            .boxed()
+    }
+}
+
+impl Arbitrary for Value {
+    type Parameters = Parameters;
+    type Strategy = BoxedStrategy<Self>;
+
+    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
+        match args {
+            Parameters::Strategy(s) => s,
+            Parameters::Parameters {
+                generate_internal_values,
+                generate_functions,
+                generate_nested,
+            } => {
+                if generate_internal_values || generate_functions {
+                    todo!("Generating internal values and functions not implemented yet")
+                } else if generate_nested {
+                    non_internal_value().boxed()
+                } else {
+                    leaf_value().boxed()
+                }
+            }
+        }
+    }
+}
+
+fn leaf_value() -> impl Strategy<Value = Value> {
+    use Value::*;
+
+    prop_oneof![
+        Just(Null),
+        any::<bool>().prop_map(Bool),
+        any::<i64>().prop_map(Integer),
+        any::<f64>().prop_map(Float),
+        any::<NixString>().prop_map(String),
+        any::<OsString>().prop_map(|s| Path(Box::new(s.into()))),
+    ]
+}
+
+fn non_internal_value() -> impl Strategy<Value = Value> {
+    leaf_value().prop_recursive(3, 5, 5, |inner| {
+        prop_oneof![
+            NixAttrs::arbitrary_with(Parameters::Strategy(inner.clone())).prop_map(Value::attrs),
+            any_with::<NixList>(Parameters::Strategy(inner)).prop_map(Value::List)
+        ]
+    })
+}