diff --git a/tests/Vantage.Core.Tests/Health/HealthCheckerTests.cs b/tests/Vantage.Core.Tests/Health/HealthCheckerTests.cs
new file mode 100644
index 0000000..8e5cbd4
--- /dev/null
+++ b/tests/Vantage.Core.Tests/Health/HealthCheckerTests.cs
@@ -0,0 +1,94 @@
+using System.Net;
+using System.Net.Sockets;
+using Vantage.Core.Health;
+using Vantage.Core.Models;
+using Vantage.Core.Tests.Fakes;
+using Xunit;
+
+namespace Vantage.Core.Tests.Health;
+
+public class HealthCheckerTests
+{
+    private static HealthCheckConfig HttpCheck() =>
+        new() { Kind = HealthKind.Http, Target = "https://service.local/health", TimeoutMs = 2000 };
+
+    [Fact]
+    public async Task Http_ExpectedStatusIsUp()
+    {
+        var checker = new HealthChecker(new HttpClient(StubHttpMessageHandler.WithStatus(HttpStatusCode.OK)));
+        var result = await checker.CheckAsync(HttpCheck(), CancellationToken.None);
+
+        Assert.Equal(HealthStatus.Up, result.Status);
+        Assert.NotNull(result.LatencyMs);
+    }
+
+    [Fact]
+    public async Task Http_UnexpectedStatusIsDegraded()
+    {
+        var checker = new HealthChecker(new HttpClient(StubHttpMessageHandler.WithStatus(HttpStatusCode.InternalServerError)));
+        var result = await checker.CheckAsync(HttpCheck(), CancellationToken.None);
+
+        Assert.Equal(HealthStatus.Degraded, result.Status);
+    }
+
+    [Fact]
+    public async Task Http_ConnectionErrorIsDown()
+    {
+        var checker = new HealthChecker(new HttpClient(StubHttpMessageHandler.Throwing(new HttpRequestException("refused"))));
+        var result = await checker.CheckAsync(HttpCheck(), CancellationToken.None);
+
+        Assert.Equal(HealthStatus.Down, result.Status);
+        Assert.Contains("refused", result.Message);
+    }
+
+    [Fact]
+    public async Task Http_TimeoutIsDown()
+    {
+        var checker = new HealthChecker(new HttpClient(StubHttpMessageHandler.Delayed(TimeSpan.FromSeconds(10), HttpStatusCode.OK)));
+        var check = HttpCheck();
+        check.TimeoutMs = 100;
+
+        var result = await checker.CheckAsync(check, CancellationToken.None);
+
+        Assert.Equal(HealthStatus.Down, result.Status);
+        Assert.Contains("Timed out", result.Message);
+    }
+
+    [Fact]
+    public async Task Tcp_OpenPortIsUp()
+    {
+        var listener = new TcpListener(IPAddress.Loopback, 0);
+        listener.Start();
+        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
+        try
+        {
+            var checker = new HealthChecker(new HttpClient());
+            var check = new HealthCheckConfig { Kind = HealthKind.Tcp, Target = $"127.0.0.1:{port}", TimeoutMs = 2000 };
+
+            var result = await checker.CheckAsync(check, CancellationToken.None);
+
+            Assert.Equal(HealthStatus.Up, result.Status);
+            Assert.NotNull(result.LatencyMs);
+        }
+        finally
+        {
+            listener.Stop();
+        }
+    }
+
+    [Fact]
+    public async Task Tcp_ClosedPortIsDown()
+    {
+        var probe = new TcpListener(IPAddress.Loopback, 0);
+        probe.Start();
+        var closedPort = ((IPEndPoint)probe.LocalEndpoint).Port;
+        probe.Stop();
+
+        var checker = new HealthChecker(new HttpClient());
+        var check = new HealthCheckConfig { Kind = HealthKind.Tcp, Target = $"127.0.0.1:{closedPort}", TimeoutMs = 2000 };
+
+        var result = await checker.CheckAsync(check, CancellationToken.None);
+
+        Assert.Equal(HealthStatus.Down, result.Status);
+    }
+}
diff --git a/tests/Vantage.Core.Tests/Health/TcpEndpointTests.cs b/tests/Vantage.Core.Tests/Health/TcpEndpointTests.cs
new file mode 100644
index 0000000..50eb715
--- /dev/null
+++ b/tests/Vantage.Core.Tests/Health/TcpEndpointTests.cs
@@ -0,0 +1,33 @@
+using Vantage.Core.Health;
+using Xunit;
+
+namespace Vantage.Core.Tests.Health;
+
+public class TcpEndpointTests
+{
+    [Fact]
+    public void Parse_HostAndPort()
+    {
+        var endpoint = TcpEndpoint.Parse("db.internal:5432");
+        Assert.Equal("db.internal", endpoint.Host);
+        Assert.Equal(5432, endpoint.Port);
+    }
+
+    [Fact]
+    public void Parse_IPv6InBrackets()
+    {
+        var endpoint = TcpEndpoint.Parse("[::1]:8080");
+        Assert.Equal("::1", endpoint.Host);
+        Assert.Equal(8080, endpoint.Port);
+    }
+
+    [Theory]
+    [InlineData("nohost")]
+    [InlineData("host:")]
+    [InlineData("host:70000")]
+    [InlineData("host:abc")]
+    public void Parse_RejectsMalformedTargets(string target)
+    {
+        Assert.Throws<FormatException>(() => TcpEndpoint.Parse(target));
+    }
+}