From 863601c2d5ae9551b2ce5262580ace437af94159 Mon Sep 17 00:00:00 2001
From: Anand Krishnamoorthi <35780660+anakrish@users.noreply.github.com>
Date: Tue, 5 Mar 2024 09:56:15 -0800
Subject: [PATCH] Propagate Undefined in object expressions (#171)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
---
 src/interpreter.rs                           |  6 ++++
 tests/interpreter/cases/nonstrict/tests.yaml | 35 ++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/interpreter.rs b/src/interpreter.rs
index e00e3f3..b3e68d9 100644
--- a/src/interpreter.rs
+++ b/src/interpreter.rs
@@ -1905,7 +1905,13 @@ impl Interpreter {
             // ( scalar | ref | var ) ":" term, the OPA
             // implementation is more like expr ":" expr
             let key = self.eval_expr(key)?;
+            if key == Value::Undefined {
+                return Ok(Value::Undefined);
+            }
             let value = self.eval_expr(value)?;
+            if value == Value::Undefined {
+                return Ok(Value::Undefined);
+            }
             object.insert(key, value);
         }
 
diff --git a/tests/interpreter/cases/nonstrict/tests.yaml b/tests/interpreter/cases/nonstrict/tests.yaml
index 665ff13..b20be4c 100644
--- a/tests/interpreter/cases/nonstrict/tests.yaml
+++ b/tests/interpreter/cases/nonstrict/tests.yaml
@@ -17,3 +17,38 @@
           a = to_number("abc")
       query: data.test
       error: "could not parse string as number"
+
+    - note: count of null error gobbled up in non strict mode
+      modules:
+        - |
+          package test
+          import rego.v1
+
+          foo := input.a
+
+          some_id := {
+            "count_value": count(foo) > 2,
+          }
+      input:
+        a: null
+      query: data.test
+      strict: false
+      want_result:
+        foo: null
+
+    - note: count of null error in strict mode
+      modules:
+        - |
+          package test
+          import rego.v1
+
+          foo := input.a
+
+          some_id := {
+            "count_value": count(foo) > 2,
+            (count(foo) > 2): "count_value",
+          }
+      input:
+        a: null
+      query: data.test
+      error: "`count` requires array/object/set/string argument"