lib/tests: Check for nested option-dependent definitions

lib/tests/modules.sh

···
 checkConfigOutput true config.enable ./define-option-dependently.nix ./declare-enable.nix ./declare-int-positive-value.nix
 checkConfigOutput 360 config.value ./define-option-dependently.nix ./declare-enable.nix ./declare-int-positive-value.nix
 checkConfigOutput 7 config.value ./define-option-dependently.nix ./declare-int-positive-value.nix
+checkConfigOutput true config.set.enable ./define-option-dependently-nested.nix ./declare-enable-nested.nix ./declare-int-positive-value-nested.nix
+checkConfigOutput 360 config.set.value ./define-option-dependently-nested.nix ./declare-enable-nested.nix ./declare-int-positive-value-nested.nix
+checkConfigOutput 7 config.set.value ./define-option-dependently-nested.nix ./declare-int-positive-value-nested.nix
 
 # Check attrsOf and lazyAttrsOf. Only lazyAttrsOf should be lazy, and only
 # attrsOf should work with conditional definitions

lib/tests/modules/declare-enable-nested.nix

···
+{ lib, ... }:
+
+{
+  options.set = {
+    enable = lib.mkOption {
+      default = false;
+      example = true;
+      type = lib.types.bool;
+      description = ''
+        Some descriptive text
+      '';
+    };
+  };
+}

lib/tests/modules/declare-int-positive-value-nested.nix

···
+{ lib, ... }:
+
+{
+  options.set = {
+    value = lib.mkOption {
+      type = lib.types.ints.positive;
+    };
+  };
+}

lib/tests/modules/define-option-dependently-nested.nix

···
+{ lib, options, ... }:
+
+# Some modules may be distributed separately and need to adapt to other modules
+# that are distributed and versioned separately.
+{
+
+  # Always defined, but the value depends on the presence of an option.
+  config.set = {
+    value = if options ? set.enable then 360 else 7;
+  }
+  # Only define if possible.
+  // lib.optionalAttrs (options ? set.enable) {
+    enable = true;
+  };
+
+}