Add a test where an action modify one of its dependency (#923)

Signed-off-by: Jeremie Dimino <jeremie@dimino.org>

test/blackbox-tests/dune.inc

@@ -1,3 +1,11 @@
+(alias
+ (name action-modifying-a-dependency)
+ (deps (package dune) (source_tree test-cases/action-modifying-a-dependency))
+ (action
+  (chdir
+   test-cases/action-modifying-a-dependency
+   (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
+
 (alias
  (name aliases)
  (deps (package dune) (source_tree test-cases/aliases))
@@ -566,6 +574,7 @@
 (alias
  (name runtest)
  (deps
+  (alias action-modifying-a-dependency)
   (alias aliases)
   (alias bad-alias-error)
   (alias block-strings)
@@ -635,6 +644,7 @@
 (alias
  (name runtest-no-deps)
  (deps
+  (alias action-modifying-a-dependency)
   (alias aliases)
   (alias bad-alias-error)
   (alias block-strings)

test/blackbox-tests/test-cases/action-modifying-a-dependency/data

@@ -0,0 +1 @@
+hello

test/blackbox-tests/test-cases/action-modifying-a-dependency/dune

@@ -0,0 +1,5 @@
+;; This test erroneously modify one of its dependencies
+(alias
+ (name   x)
+ (deps   data (universe))
+ (action (system "echo hello >> data")))

test/blackbox-tests/test-cases/action-modifying-a-dependency/dune-project

@@ -0,0 +1 @@
+(lang dune 1.0)

test/blackbox-tests/test-cases/action-modifying-a-dependency/run.t

@@ -0,0 +1,22 @@
+In this test the "x" alias depends on the file "data" but the action
+associated to "x" appends a line to "data". The current behavior is
+that the file in _build just keeps growing. The expected behavior is
+an error from Dune telling the user that this is not allowed.
+
+  $ dune build @x
+  $ cat _build/default/data
+  hello
+  hello
+
+  $ dune build @x
+  $ cat _build/default/data
+  hello
+  hello
+  hello
+
+  $ dune build @x
+  $ cat _build/default/data
+  hello
+  hello
+  hello
+  hello