tests/ssh-agent: add test coverage

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

tests/modules/services/ssh-agent/basic-service-expected.service

@@ -0,0 +1,9 @@
+[Install]
+WantedBy=default.target
+
+[Service]
+ExecStart=@openssh@/bin/ssh-agent -D -a %t/ssh-agent
+
+[Unit]
+Description=SSH authentication agent
+Documentation=man:ssh-agent(1)

tests/modules/services/ssh-agent/basic-service.nix

@@ -0,0 +1,15 @@
+{ config, ... }:
+
+{
+  config = {
+    services.ssh-agent = {
+      enable = true;
+    };
+
+    nmt.script = ''
+      assertFileContent \
+        home-files/.config/systemd/user/ssh-agent.service \
+        ${./basic-service-expected.service}
+    '';
+  };
+}

tests/modules/services/ssh-agent/default.nix

@@ -0,0 +1,5 @@
+{ lib, pkgs, ... }:
+
+lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
+  ssh-agent-basic-service = ./basic-service.nix;
+}