git-sync: add module

tests/modules/services/git-sync/basic.nix

@@ -0,0 +1,37 @@
+{ config, pkgs, ... }:
+
+{
+  config = {
+    services.git-sync = {
+      enable = true;
+      package = pkgs.writeScriptBin "dummy" "" // { outPath = "@git-sync@"; };
+      repositories.test = {
+        path = "/a/path";
+        uri = "git+ssh://user@example.com:/~user/path/to/repo.git";
+      };
+    };
+
+    nmt.script = ''
+      serviceFile=home-files/.config/systemd/user/git-sync-test.service
+
+      assertFileExists $serviceFile
+      assertFileContent $serviceFile ${
+        builtins.toFile "expected" ''
+          [Install]
+          WantedBy=default.target
+
+          [Service]
+          Environment=GIT_SYNC_DIRECTORY=/a/path
+          Environment=GIT_SYNC_COMMAND=@git-sync@/bin/git-sync
+          Environment=GIT_SYNC_REPOSITORY=git+ssh://user@example.com:/~user/path/to/repo.git
+          Environment=GIT_SYNC_INTERVAL=500
+          ExecStart=@git-sync@/bin/git-sync-on-inotify
+          Restart=on-abort
+
+          [Unit]
+          Description=Git Sync test
+        ''
+      }
+    '';
+  };
+}