test(nginx): Add simple tests to assert nginx features work

configuration/nginx/ssl.nix

@@ -1,4 +1,5 @@
 {
+  flake-inputs,
   pkgs,
   config,
   lib,
@@ -69,5 +70,68 @@
       "porkbun/api-key".owner = "acme";
       "porkbun/secret-api-key".owner = "acme";
     };
+
+    serviceTests =
+      let
+        testHostConfig =
+          { config, ... }:
+          {
+            imports = [
+              ./.
+              ../../modules/serviceTests/mocks.nix
+            ];
+
+            networking.firewall.allowedTCPPorts = [ 443 ];
+
+            security.acme.certs."tlater.net".extraDomainNames = [ config.services.nginx.domain ];
+
+            services.nginx = {
+              domain = "testHost";
+
+              virtualHosts."${config.services.nginx.domain}" = {
+                useACMEHost = "tlater.net";
+                onlySSL = true;
+                enableHSTS = true;
+                locations."/".return = "200 ok";
+              };
+            };
+          };
+      in
+      {
+        testNginxSSL = pkgs.testers.runNixOSTest {
+          name = "test-nginx-ssl";
+
+          node.specialArgs = { inherit flake-inputs; };
+          nodes = {
+            testHost = testHostConfig;
+
+            client =
+              { pkgs, ... }:
+              {
+                environment.systemPackages = [ pkgs.curl ];
+              };
+          };
+
+          testScript = ''
+            start_all()
+
+            testHost.wait_for_unit("nginx.service")
+            testHost.copy_from_vm("/var/lib/acme/tlater.net/", "certs")
+            client.copy_from_host(f"{testHost.out_dir}/certs", "/certs")
+
+            res = client.succeed(" ".join([
+                "curl",
+                "--show-error",
+                "--silent",
+                "--dump-header -",
+                "--cacert /certs/tlater.net/fullchain.pem",
+                "https://testHost",
+                "-o /dev/null"
+            ]))
+
+            assert "strict-transport-security: max-age=15552000; includeSubDomains" in res
+          '';
+        };
+      };
   };
 }