Update comments

src/lib/address_resolve/AddressResolve_DefaultImpl.cpp

@@ -157,8 +157,9 @@ bool NodeLookupResults::UpdateResults(const ResolveResult & result, const Dnssd:
         return false;
     }
 
-    // we can insert IF AND ONLY IF we are not duplicating an existing entry
-    // TODO: implement
+    // we are guaranteed no duplicates here:
+    // - insertAtIndex MUST be with some score that is `< newScore`, so all
+    //   addresses with a `newScore` were duplicate-checked
 
     // Move the following valid entries one level down.
     for (auto i = count; i > insertAtIndex; i--)

src/lib/address_resolve/tests/TestAddressResolve_DefaultImpl.cpp

@@ -95,6 +95,43 @@ Transport::PeerAddress GetAddressWithHighScore(uint16_t port = CHIP_PORT, Inet::
     return Transport::PeerAddress::UDP(ipAddress, port, interfaceId);
 }
 
+TEST(TestAddressResolveDefaultImpl, UpdateResultsDoesNotAddDuplicatesWhenFull) {
+    Impl::NodeLookupResults results;
+    ASSERT_EQ(results.count, 0);
+
+    for (auto i = 0; i < kNumberOfAvailableSlots; i++)
+    {
+        ResolveResult result;
+        result.address = GetAddressWithLowScore(i + 10);
+        ASSERT_TRUE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kUniqueLocal));
+    }
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+
+    // Adding another one should fail as there is no more room
+    ResolveResult result;
+    result.address = GetAddressWithLowScore(5);
+    ASSERT_FALSE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kUniqueLocal));
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+
+    // however one with higher priority should work
+    result.address = GetAddressWithHighScore();
+    ASSERT_TRUE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kGlobalUnicast));
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+
+    // however not duplicate
+    ASSERT_FALSE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kGlobalUnicast));
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+
+    // another higher priority one
+    result.address = GetAddressWithMediumScore();
+    ASSERT_TRUE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kLinkLocal));
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+
+    // however not duplicate
+    ASSERT_FALSE(results.UpdateResults(result, Dnssd::IPAddressSorter::IpScore::kLinkLocal));
+    ASSERT_EQ(results.count, kNumberOfAvailableSlots);
+}
+
 TEST(TestAddressResolveDefaultImpl, UpdateResultsDoesNotAddDuplicates)
 {
     static_assert(Impl::kNodeLookupResultsLen >= 3, "Test uses 3 address slots");