Simplify test build

Thanks to @emillon for pointing out all the shortcut that dune allows to
avoid declaring things over and over.

Author: Leonidas-from-XIV

test/bin/mdx-dune-gen/misc/non-deterministic/dune

@@ -1,9 +1,7 @@
 (rule
- (target dune_gen.ml)
- (action
-  (with-stdout-to
-   %{target}
-   (run ocaml-mdx dune-gen))))
+ (with-stdout-to
+  dune_gen.ml
+  (run ocaml-mdx dune-gen)))
 
 (executable
  (name dune_gen)
@@ -12,33 +10,23 @@
  (libraries mdx.test))
 
 (rule
- (target dune-mdx-nondeterministic.deterministic)
- (deps
-  dune_gen.exe
-  (:input dune-mdx-nondeterministic))
- (action
-  (with-stdout-to
-   %{target}
-   (run ./dune_gen.exe %{input}))))
+ (with-stdout-to
+  dune-mdx-nondeterministic.deterministic
+  (run ./dune_gen.exe %{dep:dune-mdx-nondeterministic})))
 
 (rule
- (target dune-mdx-nondeterministic.nondeterministic)
- (deps
-  dune_gen.exe
-  (:input dune-mdx-nondeterministic))
- (action
-  (setenv
-   MDX_RUN_NON_DETERMINISTIC
-   1
-   (with-stdout-to
-    %{target}
-    (run ./dune_gen.exe %{input})))))
+ (setenv
+  MDX_RUN_NON_DETERMINISTIC
+  1
+  (with-stdout-to
+   dune-mdx-nondeterministic.nondeterministic
+   (run ./dune_gen.exe %{dep:dune-mdx-nondeterministic}))))
 
 (rule
  (alias runtest)
  (action
-  (diff %{dep:dune-mdx-nondeterministic.expected}
-    %{dep:dune-mdx-nondeterministic.deterministic})))
+  (diff dune-mdx-nondeterministic.expected
+    dune-mdx-nondeterministic.deterministic)))
 
 ;; make sure the non-deterministic is different from the deterministic