diff --git a/common/jinja/value.cpp b/common/jinja/value.cpp
index f254ae9251..ec4c649648 100644
--- a/common/jinja/value.cpp
+++ b/common/jinja/value.cpp
@@ -393,6 +393,30 @@ const func_builtins & global_builtins() {
         {"test_is_lt", test_compare_fn<value_compare_op::lt>},
         {"test_is_lessthan", test_compare_fn<value_compare_op::lt>},
         {"test_is_ne", test_compare_fn<value_compare_op::ne>},
+        {"test_is_in", [](const func_args & args) -> value {
+            args.ensure_count(2);
+            auto needle   = args.get_pos(0);
+            auto haystack = args.get_pos(1);
+            if (is_val<value_undefined>(haystack)) {
+                return mk_val<value_bool>(false);
+            }
+            if (is_val<value_array>(haystack)) {
+                for (const auto & item : haystack->as_array()) {
+                    if (*needle == *item) {
+                        return mk_val<value_bool>(true);
+                    }
+                }
+                return mk_val<value_bool>(false);
+            }
+            if (is_val<value_string>(haystack) && is_val<value_string>(needle)) {
+                return mk_val<value_bool>(
+                    haystack->as_string().str().find(needle->as_string().str()) != std::string::npos);
+            }
+            if (is_val<value_object>(haystack)) {
+                return mk_val<value_bool>(haystack->has_key(needle));
+            }
+            throw raised_exception("'in' test expects an iterable");
+        }},
         {"test_is_test", [](const func_args & args) -> value {
             args.ensure_vals<value_string>();
             auto & builtins = global_builtins();
diff --git a/tests/test-jinja.cpp b/tests/test-jinja.cpp
index f6114f1e2f..a37cb02737 100644
--- a/tests/test-jinja.cpp
+++ b/tests/test-jinja.cpp
@@ -1036,6 +1036,42 @@ static void test_tests(testing & t) {
         json::object(),
         "yes"
     );
+
+    test_template(t, "is in (array, true)",
+        "{{ 'yes' if 2 is in([1, 2, 3]) }}",
+        json::object(),
+        "yes"
+    );
+
+    test_template(t, "is in (array, false)",
+        "{{ 'yes' if 5 is in([1, 2, 3]) else 'no' }}",
+        json::object(),
+        "no"
+    );
+
+    test_template(t, "is in (string)",
+        "{{ 'yes' if 'bc' is in('abcde') }}",
+        json::object(),
+        "yes"
+    );
+
+    test_template(t, "is in (object keys)",
+        "{{ 'yes' if 'a' is in(obj) }}",
+        {{"obj", {{"a", 1}, {"b", 2}}}},
+        "yes"
+    );
+
+    test_template(t, "reject with in test",
+        "{{ items | reject('in', skip) | join(', ') }}",
+        {{"items", json::array({"a", "b", "c", "d"})}, {"skip", json::array({"b", "d"})}},
+        "a, c"
+    );
+
+    test_template(t, "select with in test",
+        "{{ items | select('in', keep) | join(', ') }}",
+        {{"items", json::array({"a", "b", "c", "d"})}, {"keep", json::array({"b", "c"})}},
+        "b, c"
+    );
 }
 
 static void test_string_methods(testing & t) {