nixos/lib/testing: Pull callTest in

It makes more sense to let the modules guide the invocation of this
function rather than to produce a data structure and then consume it
immmediately.

Maybe the same should be done for exposeIntermediateAttrs. It'd turn
the two functions into a catamorphism that's integrated into the
modules.

nixos/lib/testing/default.nix

@@ -2,10 +2,9 @@
 let
 
   evalTest = module: lib.evalModules { modules = testModules ++ [ module ]; };
-  runTest = module: (evalTest ({ config, ... }: { imports = [ module ]; result = config.test; })).config.result;
+  runTest = module: (evalTest ({ lib, config, ... }: { imports = [ module ]; })).config.result;
 
   testModules = [
-    ./call-test.nix
     ./driver.nix
     ./interactive.nix
     ./legacy.nix

nixos/lib/testing/matrix.nix

@@ -323,7 +323,7 @@ in
         nextDecision = (lib.head sortedEnable).name;
       in
       if sortedEnable == [ ]
-      then config
+      then config.callTest config
       else
         lib.recurseIntoAttrs
           (

nixos/tests/all-tests.nix

@@ -63,7 +63,7 @@ let
           // exposeIntermediateAttrs tree
         else callTest tree;
 
-      runTest = arg: let r = doRunTest arg; in findTests r;
+      runTest = arg: let r = doRunTest arg; in r;
       runTestOn = systems: arg:
         if elem system systems then runTest arg
         else {};