test(container): render Cell slices test against .zon input

src/container.zig

@@ -174,6 +174,90 @@ pub const Border = packed struct {
             }
         }
     }
+
+    test "all sides" {
+        const event = @import("event.zig");
+        const testing = @import("testing.zig");
+
+        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+            .border = .{
+                .color = .green,
+                .sides = .all,
+            },
+        }, .{});
+        defer container.deinit();
+
+        try testing.expectContainerScreen(.{
+            .rows = 20,
+            .cols = 30,
+        }, &container, @import("test/container/border.all.zon"));
+    }
+
+    test "vertical sides" {
+        const event = @import("event.zig");
+        const testing = @import("testing.zig");
+
+        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+            .border = .{
+                .color = .green,
+                .sides = .vertical,
+            },
+        }, .{});
+        defer container.deinit();
+
+        try testing.expectContainerScreen(.{
+            .rows = 20,
+            .cols = 30,
+        }, &container, @import("test/container/border.vertical.zon"));
+    }
+
+    test "horizontal sides" {
+        const event = @import("event.zig");
+        const testing = @import("testing.zig");
+
+        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+            .border = .{
+                .color = .blue,
+                .sides = .horizontal,
+            },
+        }, .{});
+        defer container.deinit();
+
+        try testing.expectContainerScreen(.{
+            .rows = 20,
+            .cols = 30,
+        }, &container, @import("test/container/border.horizontal.zon"));
+    }
+
+    // NOTE: this test serves as a template for further test creations. It should not run for testing.
+    // test "create container zon file" {
+    //     const event = @import("event.zig");
+    //     const testing = @import("testing.zig");
+
+    //     var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+    //         .border = .{
+    //             .color = .green,
+    //             .sides = .horizontal,
+    //         },
+    //     }, .{});
+    //     defer container.deinit();
+
+    //     const size: Size = .{
+    //         .rows = 20,
+    //         .cols = 30,
+    //     };
+
+    //     const file = try std.fs.cwd().createFile("src/test/container/border.horizontal.zon", .{ .truncate = true });
+    //     defer file.close();
+
+    //     const allocator = std.testing.allocator;
+    //     var renderer: testing.Renderer = .init(allocator, size);
+    //     defer renderer.deinit();
+
+    //     try container.handle(.{ .resize = size });
+    //     try renderer.render(Container(event.SystemEvent), &container);
+    //     try renderer.save(file.writer());
+    // }
 };
 
 /// Rectangle configuration struct