diff --git a/src/main.zig b/src/main.zig
index 6bba538..4585c17 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -283,3 +283,85 @@ pub fn main() !void {
         try stdout.print("Unrecognized sentence: {s}\n", .{args[1]});
     }
 }
+test "extractDevice single word exact match" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("kitchen", "192.168.1.100");
+    try devices.put("bedroom", "192.168.1.101");
+
+    var object_words = [_][]const u8{"kitchen"};
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expectEqualStrings("192.168.1.100", result.?.value_ptr.*);
+}
+
+test "extractDevice single word case insensitive" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("kitchen", "192.168.1.100");
+
+    var object_words = [_][]const u8{"Kitchen"};
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expectEqualStrings("192.168.1.100", result.?.value_ptr.*);
+}
+
+test "extractDevice two words exact match" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("bedroom light", "192.168.1.100");
+
+    var object_words = [_][]const u8{ "bedroom", "light" };
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expectEqualStrings("192.168.1.100", result.?.value_ptr.*);
+}
+
+test "extractDevice two words case insensitive" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("bedroom light", "192.168.1.100");
+
+    var object_words = [_][]const u8{ "Bedroom", "Light" };
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expectEqualStrings("192.168.1.100", result.?.value_ptr.*);
+}
+
+test "extractDevice not found" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("kitchen", "192.168.1.100");
+
+    var object_words = [_][]const u8{"bathroom"};
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expect(result == null);
+}
+
+test "extractDevice empty words" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    var object_words = [_][]const u8{};
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expect(result == null);
+}
+
+test "extractDevice fallback to shorter match" {
+    var devices = std.StringHashMap([]const u8).init(std.testing.allocator);
+    defer devices.deinit();
+
+    try devices.put("kitchen", "192.168.1.100");
+
+    var object_words = [_][]const u8{ "kitchen", "ceiling", "light" };
+    const result = try extractDevice(std.testing.allocator, object_words[0..], &devices);
+
+    try std.testing.expectEqualStrings("192.168.1.100", result.?.value_ptr.*);
+}