tests: Allow to test multiple derivations in a single test derivation

tests/default.nix

@@ -7,7 +7,7 @@
 }:
 let
   fetchTests = import ./fetch-tests.nix;
-  test-derivation = import ./test-derivation.nix { inherit pkgs makeNixvimWithModule; };
+  test-derivation = import ./test-derivation.nix { inherit pkgs makeNixvimWithModule lib; };
   inherit (test-derivation) mkTestDerivationFromNixvimModule;
 
   # List of files containing configurations

tests/test-derivation.nix

@@ -1,40 +1,63 @@
-{ pkgs, makeNixvimWithModule, ... }:
+{
+  pkgs,
+  lib ? pkgs.lib,
+  makeNixvimWithModule,
+  ...
+}:
 let
   # Create a nix derivation from a nixvim executable.
   # The build phase simply consists in running the provided nvim binary.
   mkTestDerivationFromNvim =
     {
       name,
-      nvim,
+      nvim ? null,
+      tests ? [ ],
       dontRun ? false,
       ...
     }:
+    # At least one of these should be undefined
+    assert lib.assertMsg (tests == [ ] || nvim == null) "Both nvim & tests can't be supplied";
+    let
+      nvimAsList = lib.optional (nvim != null) {
+        derivation = nvim;
+        inherit name dontRun;
+      };
+
+      testList = tests ++ nvimAsList;
+    in
     pkgs.stdenv.mkDerivation {
       inherit name;
 
-      nativeBuildInputs = [
+      nativeBuildInputs = [ pkgs.docker-client ];
-        nvim
-        pkgs.docker-client
-      ];
 
       dontUnpack = true;
       # We need to set HOME because neovim will try to create some files
       #
       # Because neovim does not return an exitcode when quitting we need to check if there are
       # errors on stderr
-      buildPhase =
+      buildPhase = lib.optionalString (!dontRun) (
-        if !dontRun then
         ''
           mkdir -p .cache/nvim
+        ''
+        + lib.concatStringsSep "\n" (
+          builtins.map (
+            {
+              derivation,
+              name,
+              dontRun ? false,
+            }:
+            lib.optionalString (!dontRun) ''
+              echo "Running test for ${name}"
 
-            output=$(HOME=$(realpath .) nvim -mn --headless "+q" 2>&1 >/dev/null)
+              output=$(HOME=$(realpath .) ${lib.getExe derivation} -mn --headless "+q" 2>&1 >/dev/null)
               if [[ -n $output ]]; then
                 echo "ERROR: $output"
                 exit 1
               fi
             ''
-        else
+          ) testList
-          '''';
+        )
+      );
 
       # If we don't do this nix is not happy
       installPhase = ''
@@ -48,17 +71,35 @@ let
     {
       name ? "nixvim-check",
       pkgs ? pkgs,
-      module,
+      module ? null,
+      tests ? [ ],
       extraSpecialArgs ? { },
       dontRun ? false,
     }:
+    # At least one of these should be undefined
+    assert lib.assertMsg (tests == [ ] || module == null) "Both module & tests can't be supplied";
     let
-      nvim = makeNixvimWithModule {
+      moduleAsList = lib.optional (module != null) { inherit module name; };
+      moduleList = tests ++ moduleAsList;
+      testDerivations = builtins.map (
+        {
+          module,
+          name,
+          dontRun ? false,
+        }:
+        {
+          derivation = makeNixvimWithModule {
             inherit pkgs module extraSpecialArgs;
             _nixvimTests = true;
           };
+          inherit name dontRun;
+        }
+      ) moduleList;
     in
-    mkTestDerivationFromNvim { inherit name nvim dontRun; };
+    mkTestDerivationFromNvim {
+      inherit name dontRun;
+      tests = testDerivations;
+    };
 in
 {
   inherit mkTestDerivationFromNvim mkTestDerivationFromNixvimModule;