diff --git a/lib/src/modules/default.test.nix b/lib/src/modules/default.test.nix
index 9b816f2..00e9396 100644
--- a/lib/src/modules/default.test.nix
+++ b/lib/src/modules/default.test.nix
@@ -205,52 +205,57 @@ in
       let
         # Simple backtracking algorithm to generate all combinations of a list's
         # elements without ordering, in .
-        combinations = set:
+        combinations =
+          set:
           let
             n = builtins.length set;
-            genIndices = combinations':
+            genIndices =
+              combinations':
               let
                 prev = builtins.head combinations';
                 k = builtins.length prev;
                 first = builtins.head prev;
                 next' =
                   # Generate the next combination of length k
-                  if k > 0 && first+1 < n then [(first+1)] ++ (builtins.tail prev)
+                  if k > 0 && first + 1 < n then
+                    [ (first + 1) ] ++ (builtins.tail prev)
                   # We have generated all combinations of length k, generate the first
                   # (trivial) combination of length k+1
-                  else builtins.genList (i: i) (k+1);
+                  else
+                    builtins.genList (i: i) (k + 1);
                 next = builtins.deepSeq next' next';
               in
               # Generate the very first (trivial) combination
-              if combinations' == [ ] then genIndices [ [ ] ]
+              if combinations' == [ ] then
+                genIndices [ [ ] ]
               # We have generated all combinations of length 0 to n, return
-              else if k >= n then combinations'
+              else if k >= n then
+                combinations'
               # Generate the next combination and continue
-              else genIndices ([next] ++ combinations');
+              else
+                genIndices ([ next ] ++ combinations');
             select = indices: builtins.map (builtins.elemAt set) indices;
           in
-            if set == [ ] then [ ]
-            else builtins.map select (genIndices []);
+          if set == [ ] then [ ] else builtins.map select (genIndices [ ]);
 
         keys = combinations (lib.modules.VALID_KEYS ++ lib.modules.VALID_INCLUDE_KEYS);
-        sets =
-          builtins.map
-          (names:
-            builtins.listToAttrs
-            (builtins.map (name: { value = null; inherit name; }) names)
+        sets = builtins.map (
+          names:
+          builtins.listToAttrs (
+            builtins.map (name: {
+              value = null;
+              inherit name;
+            }) names
           )
-          keys;
-        validated =
-          builtins.map
-          (set: {
-            inherit set;
-            include = lib.modules.validate.include set;
-            module = lib.modules.validate.keys set;
-          })
-          sets;
-        bothValid = {include, module, ...}: include && module;
+        ) keys;
+        validated = builtins.map (set: {
+          inherit set;
+          include = lib.modules.validate.include set;
+          module = lib.modules.validate.keys set;
+        }) sets;
+        bothValid = { include, module, ... }: include && module;
       in
-      ! builtins.any bothValid validated;
+      !builtins.any bothValid validated;
   };
 
   "normalize" = {