nix: clean up directory structure

Tests for fpkg is going to be in ./cmd/fpkg, so this central tests directory is no longer necessary.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/default.nix

@@ -0,0 +1,47 @@
+{
+  lib,
+  nixosTest,
+  writeShellScriptBin,
+
+  system,
+  self,
+  withRace ? false,
+}:
+
+nixosTest {
+  name = "fortify" + (if withRace then "-race" else "");
+  nodes.machine =
+    { options, pkgs, ... }:
+    {
+      environment.systemPackages = [
+        # For go tests:
+        self.packages.${system}.fhs
+        (writeShellScriptBin "fortify-src" "echo -n ${self.packages.${system}.fortify.src}")
+      ];
+
+      # Run with Go race detector:
+      environment.fortify = lib.mkIf withRace rec {
+        # race detector does not support static linking
+        package = (pkgs.callPackage ../package.nix { }).overrideAttrs (previousAttrs: {
+          GOFLAGS = previousAttrs.GOFLAGS ++ [ "-race" ];
+        });
+        fsuPackage = options.environment.fortify.fsuPackage.default.override { fortify = package; };
+      };
+
+      imports = [
+        ./configuration.nix
+
+        self.nixosModules.fortify
+        self.inputs.home-manager.nixosModules.home-manager
+      ];
+    };
+
+  # adapted from nixos sway integration tests
+
+  # testScriptWithTypes:49: error: Cannot call function of unknown type
+  #           (machine.succeed if succeed else machine.execute)(
+  #           ^
+  # Found 1 error in 1 file (checked 1 source file)
+  skipTypeCheck = true;
+  testScript = builtins.readFile ./test.py;
+}