tests: add SmokeTestBase helper for HTTP smoke assertions

Smoke tests for the Jalon 0 'Tests d'integration smoke par BC'
item need a small helper to:
- issue a GET on an in-memory test server (HttpClient built by
  TestWebApplicationFactory<Program>);
- assert that the response is 2xx (page served), 3xx (redirect
  to login) or 401/403 (anonymous rejected). Anything else —
  404 route missing, 5xx server crash, connection refused —
  fails the test.

This commit only introduces the base class. Subsequent commits
add the per-BC smoke tests (Account, Blog, etc.).

src/Yavsc.Org.Tests/Smoke/SmokeTestBase.cs

@@ -0,0 +1,57 @@
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Yavsc.Org.Tests.Smoke;
+
+/// <summary>
+/// Base for the smoke tests covering the production hosts
+/// (Yavsc.Org / Yavsc.Api / Yavsc.Blogs). One smoke test per
+/// bounded context (BC): each test hits one GET endpoint and
+/// asserts a 2xx or 3xx status, with no follow-up redirect.
+/// Together they satisfy the 'Tests d'intégration smoke par BC'
+/// item of Jalon 0 in <c>ROADMAP.md</c>.
+///
+/// Status code policy:
+/// - 200 OK : endpoint serves a page.
+/// - 302 / 301 : endpoint requires auth and redirects to login
+///   (acceptable smoke signal: routing + middleware are wired).
+/// - 401 / 403 : endpoint exists but rejects anonymous (acceptable
+///   for API smoke tests where the smoke is "the host boots").
+/// Anything else (404, 500, connection refused) is a failure.
+/// </summary>
+public abstract class SmokeTestBase
+{
+    /// <summary>
+    /// Issue a GET against <paramref name="relativePath"/> on the
+    /// in-memory test server. Returns the raw HttpResponseMessage
+    /// without following redirects — the test asserts on the first
+    /// hop, not the eventual page.
+    /// </summary>
+    protected static async Task<HttpResponseMessage> GetRaw(
+        HttpClient client, string relativePath)
+    {
+        Assert.NotNull(client);
+        var request = new HttpRequestMessage(HttpMethod.Get, relativePath);
+        return await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+    }
+
+    /// <summary>
+    /// Smoke assertion: a GET on <paramref name="relativePath"/>
+    /// returns 2xx (page served) or 3xx (redirect to login) or
+    /// 401/403 (anonymous rejected by [Authorize]). Anything else
+    /// — 404 (route missing), 5xx (server crash), connection
+    /// refused (host not started) — fails the test.
+    /// </summary>
+    protected static async Task AssertResponds(
+        HttpClient client, string relativePath)
+    {
+        var response = await GetRaw(client, relativePath);
+        var status = (int)response.StatusCode;
+        Assert.True(
+            status >= 200 && status < 400 || status == 401 || status == 403,
+            $"GET {relativePath} returned {status} {response.StatusCode}, " +
+            "expected 2xx/3xx (page or redirect) or 401/403 (auth required).");
+    }
+}