feat(clan/services): init test-suite for eval test

lib/distributed-service/tests/default.nix

@@ -0,0 +1,61 @@
+{
+  lib,
+  ...
+}:
+let
+  inherit (lib)
+    evalModules
+    mkOption
+    types
+    ;
+
+  inherit (types)
+    submodule
+    attrsOf
+    str
+    ;
+
+  evalInventory =
+    m:
+    (evalModules {
+      # Static modules
+      modules = [
+        ../../inventory/build-inventory/interface.nix
+        {
+          modules.test = {};
+        }
+        m
+      ];
+    }).config;
+
+  flakeFixture = { inputs = {}; };
+
+  callInventoryAdapter = inventoryModule: import ../inventory-adapter.nix { inherit lib; flake = flakeFixture; inventory = evalInventory inventoryModule; };
+in
+{
+  test_simple =
+    let res = callInventoryAdapter {
+      # Authored module
+      # A minimal module looks like this
+      # It isn't exactly doing anything but it's a valid module that produces an output
+      modules."simple-module" = {
+        _class = "clan.service";
+        manifest = {
+          name = "netwitness";
+        };
+      };
+      # User config
+      instances."instance_foo" = {
+        module = {
+          name = "simple-module";
+        };
+      };
+    };
+    in
+  {
+    # Test that the module is mapped into the output
+    # We might change the attribute name in the future
+    expr = res.evals ? "self-simple-module";
+    expected = true;
+  };
+}