flake-modules/tests: introduce callTest(s) auto-arg helpers

Allows using the `callPackage(s)` pattern on tests.

For now, just migrate the existing `pkgs.callPackage` usage.

Author: MattSturgeon

tests/default.nix

@@ -8,7 +8,23 @@
   self, # The flake instance
 }:
 let
-  inherit (self.legacyPackages.${system}) nixvimConfiguration;
+  autoArgs = pkgs // {
+    inherit
+      helpers
+      lib
+      makeNixvimWithModule
+      pkgsUnfree
+      self
+      system
+      ;
+    inherit (self.legacyPackages.${system}) nixvimConfiguration;
+    inherit (self.lib.${system}.check) mkTestDerivationFromNixvimModule;
+    # Recursive:
+    inherit callTest callTests;
+  };
+
+  callTest = lib.callPackageWith autoArgs;
+  callTests = lib.callPackagesWith autoArgs;
 in
 {
   extra-args-tests = import ./extra-args.nix {
@@ -21,9 +37,7 @@ in
     inherit pkgs makeNixvimWithModule;
     inherit (self.lib.${system}.check) mkTestDerivationFromNixvimModule;
   };
-  failing-tests = pkgs.callPackage ./failing-tests.nix {
-    inherit (self.lib.${system}.check) mkTestDerivationFromNixvimModule;
-  };
+  failing-tests = callTest ./failing-tests.nix { };
   no-flake = import ./no-flake.nix {
     inherit system;
     inherit (self.lib.${system}.check) mkTestDerivationFromNvim;
@@ -34,10 +48,10 @@ in
     inherit (pkgs) lib;
   };
   maintainers = import ./maintainers.nix { inherit pkgs; };
-  plugins-by-name = pkgs.callPackage ./plugins-by-name.nix { inherit nixvimConfiguration; };
-  generated = pkgs.callPackage ./generated.nix { };
-  package-options = pkgs.callPackage ./package-options.nix { inherit nixvimConfiguration; };
-  lsp-all-servers = pkgs.callPackage ./lsp-servers.nix { inherit nixvimConfiguration; };
+  plugins-by-name = callTest ./plugins-by-name.nix { };
+  generated = callTest ./generated.nix { };
+  package-options = callTest ./package-options.nix { };
+  lsp-all-servers = callTest ./lsp-servers.nix { };
 }
 # Tests generated from ./test-sources
 # Grouped as a number of link-farms in the form { test-1, test-2, ... test-N }