direnv: add initial test for bash integration

(cherry picked from commit 575cd4b8ba)

tests/default.nix

@@ -30,6 +30,7 @@ import nmt {
     ./modules/programs/bash
     ./modules/programs/browserpass
     ./modules/programs/dircolors
+    ./modules/programs/direnv
     ./modules/programs/fish
     ./modules/programs/git
     ./modules/programs/gpg

tests/modules/programs/direnv/bash.nix

@@ -0,0 +1,17 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.bash.enable = true;
+    programs.direnv.enable = true;
+
+    nmt.script = ''
+      assertFileExists home-files/.bashrc
+      assertFileRegex \
+        home-files/.bashrc \
+        'eval "\$(/nix/store/.*direnv.*/bin/direnv hook bash)"'
+    '';
+  };
+}

tests/modules/programs/direnv/default.nix

@@ -0,0 +1,4 @@
+{
+  direnv-bash = ./bash.nix;
+  direnv-stdlib = ./stdlib.nix;
+}

tests/modules/programs/direnv/stdlib.nix

@@ -0,0 +1,19 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let expectedContent = "something important";
+in {
+  config = {
+    programs.bash.enable = true;
+    programs.direnv.enable = true;
+    programs.direnv.stdlib = expectedContent;
+
+    nmt.script = ''
+      assertFileExists home-files/.bashrc
+      assertFileRegex \
+        home-files/.config/direnv/direnvrc \
+        '${expectedContent}'
+    '';
+  };
+}