feat: unit tests

outputs/riscv64-linux/default.nix

@@ -31,8 +31,8 @@ in
     inherit data; # for debugging purposes
 
     # NixOS's unit tests.
-    # unit-tests = haumea.lib.loadEvalTests {
-    #   src = ./tests;
-    #   inputs = args;
-    # };
+    unitTests = haumea.lib.loadEvalTests {
+      src = ./tests;
+      inputs = args // {inherit outputs;};
+    };
   }

outputs/riscv64-linux/tests/hostname/expected.nix

@@ -0,0 +1,8 @@
+{
+  lib,
+  outputs,
+}: let
+  hostsNames = builtins.attrNames outputs.nixosConfigurations;
+  expected = lib.genAttrs hostsNames (name: name);
+in
+  expected

outputs/riscv64-linux/tests/hostname/expr.nix

@@ -0,0 +1,9 @@
+{
+  lib,
+  outputs,
+}:
+lib.genAttrs
+(builtins.attrNames outputs.nixosConfigurations)
+(
+  name: outputs.nixosConfigurations.${name}.config.networking.hostName
+)