feat(health): canonical JSON health response writer

2026-06-01 06:42:24 -04:00
parent 5fb579c2f0
commit d1b837e718
4 changed files with 207 additions and 3 deletions
@@ -0,0 +1,92 @@
+using System.Net;
+using System.Net.Http.Json;
+using System.Text.Json;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Microsoft.Extensions.DependencyInjection;
+using ZB.MOM.WW.Health;
+
+namespace ZB.MOM.WW.Health.Tests;
+
+/// <summary>
+/// Verifies the canonical JSON response writer (<see cref="ZbHealthWriter.WriteJsonAsync"/>):
+/// the JSON body shape, the <c>application/json</c> content type, and that the framework's
+/// status-to-HTTP mapping (Healthy/Degraded → 200, Unhealthy → 503) is preserved when the
+/// writer is wired onto the ready/active tiers by <see cref="ZbHealthEndpointExtensions.MapZbHealth"/>.
+/// </summary>
+public sealed class ResponseWriterTests
+{
+    private sealed class StubHealthCheck : IHealthCheck
+    {
+        private readonly HealthCheckResult _result;
+
+        public StubHealthCheck(HealthStatus status, string? description = null) =>
+            _result = new HealthCheckResult(status, description);
+
+        public Task<HealthCheckResult> CheckHealthAsync(
+            HealthCheckContext context,
+            CancellationToken cancellationToken = default) => Task.FromResult(_result);
+    }
+
+    private static async Task<HttpResponseMessage> GetReadyAsync(
+        HealthStatus status, string description = "db reachable")
+    {
+        var builder = WebApplication.CreateBuilder();
+        builder.WebHost.UseTestServer();
+        builder.Services.AddHealthChecks()
+            .AddCheck("db", new StubHealthCheck(status, description), tags: new[] { ZbHealthTags.Ready });
+
+        await using var app = builder.Build();
+        app.MapZbHealth();
+        await app.StartAsync();
+
+        var client = app.GetTestClient();
+        return await client.GetAsync("/health/ready");
+    }
+
+    [Fact]
+    public async Task ReadyEndpoint_Healthy_WritesJsonBody_With200()
+    {
+        var response = await GetReadyAsync(HealthStatus.Healthy);
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Equal("application/json", response.Content.Headers.ContentType?.MediaType);
+
+        using var doc = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
+        var root = doc.RootElement;
+
+        Assert.Equal("Healthy", root.GetProperty("status").GetString());
+        Assert.Equal(JsonValueKind.Number, root.GetProperty("totalDurationMs").ValueKind);
+
+        var entries = root.GetProperty("entries");
+        var db = entries.GetProperty("db");
+        Assert.Equal("Healthy", db.GetProperty("status").GetString());
+        Assert.Equal("db reachable", db.GetProperty("description").GetString());
+    }
+
+    [Fact]
+    public async Task ReadyEndpoint_Degraded_Returns200_WithDegradedStatus()
+    {
+        var response = await GetReadyAsync(HealthStatus.Degraded);
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Equal("application/json", response.Content.Headers.ContentType?.MediaType);
+
+        using var doc = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
+        Assert.Equal("Degraded", doc.RootElement.GetProperty("status").GetString());
+    }
+
+    [Fact]
+    public async Task ReadyEndpoint_Unhealthy_Returns503_WithUnhealthyStatus()
+    {
+        var response = await GetReadyAsync(HealthStatus.Unhealthy);
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+        Assert.Equal("application/json", response.Content.Headers.ContentType?.MediaType);
+
+        using var doc = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
+        Assert.Equal("Unhealthy", doc.RootElement.GetProperty("status").GetString());
+    }
+}