Refs #373 -- Added TupleIn subqueries.

tests/foreign_object/test_tuple_lookups.py

@@ -11,6 +11,7 @@ from django.db.models.fields.tuple_lookups import (
     TupleLessThan,
     TupleLessThanOrEqual,
 )
+from django.db.models.lookups import In
 from django.test import TestCase, skipUnlessDBFeature
 
 from .models import Contact, Customer
@@ -126,6 +127,46 @@ class TupleLookupsTests(TestCase):
             (self.contact_1, self.contact_2, self.contact_5),
         )
 
+    def test_tuple_in_subquery_must_be_query(self):
+        lhs = (F("customer_code"), F("company_code"))
+        # If rhs is any non-Query object with an as_sql() function.
+        rhs = In(F("customer_code"), [1, 2, 3])
+        with self.assertRaisesMessage(
+            ValueError,
+            "'in' subquery lookup of ('customer_code', 'company_code') "
+            "must be a Query object (received 'In')",
+        ):
+            TupleIn(lhs, rhs)
+
+    def test_tuple_in_subquery_must_have_2_fields(self):
+        lhs = (F("customer_code"), F("company_code"))
+        rhs = Customer.objects.values_list("customer_id").query
+        with self.assertRaisesMessage(
+            ValueError,
+            "'in' subquery lookup of ('customer_code', 'company_code') "
+            "must have 2 fields (received 1)",
+        ):
+            TupleIn(lhs, rhs)
+
+    def test_tuple_in_subquery(self):
+        customers = Customer.objects.values_list("customer_id", "company")
+        test_cases = (
+            (self.customer_1, (self.contact_1, self.contact_2, self.contact_5)),
+            (self.customer_2, (self.contact_3,)),
+            (self.customer_3, (self.contact_4,)),
+            (self.customer_4, ()),
+            (self.customer_5, (self.contact_6,)),
+        )
+
+        for customer, contacts in test_cases:
+            lhs = (F("customer_code"), F("company_code"))
+            rhs = customers.filter(id=customer.id).query
+            lookup = TupleIn(lhs, rhs)
+            qs = Contact.objects.filter(lookup).order_by("id")
+
+            with self.subTest(customer=customer.id, query=str(qs.query)):
+                self.assertSequenceEqual(qs, contacts)
+
     def test_tuple_in_rhs_must_be_collection_of_tuples_or_lists(self):
         test_cases = (
             (1, 2, 3),