Moving mojo/validation test into LayoutTests

mojo/public/interfaces/bindings/tests/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("../../../tools/bindings/mojom.gni")
 
+group("tests") {
+  testonly = true
+  deps = [
+    ":test_data",
+    ":test_interfaces",
+  ]
+}
+
+action("test_data") {
+  script = "gen_data_files_list.py"
+  outputs = [
+    "$target_gen_dir/data_files.txt",

[yzshen1, 2017/03/23 17:46:20]

please use a more specific name such as ".../data/validation_files.txt"

+    "$target_gen_dir/data",

[yzshen1, 2017/03/23 17:46:20]

I think outputs should list all the files instead of a directory.

That probably means you need to have two rules: one to generate the
data_files.txt (which should include both .data and .expected files); the other
to copy all the files in data_files.txt, and list all the copied files as
outputs.

GN's "read_file" and "copy" are useful. Please see "gn help read_file" and "gn
help copy".

[damargulis, 2017/03/24 19:44:48]

I've run into some problems using the "read_file" and "copy" commands for this
pattern.  The copy action ensures that the source files exist at gn gen time,
otherwise it throws an error and aborts.  This means that if I list the sources
by using `sources = read_file("$target_gen_dir/validation_files.txt")`, that
validation_files.txt file needs to already exist.  Listing the script action as
a dependency doesn't help, because the file still won't be created until ninja
is run, so it will not exist at gn gen time.  Copy will also not accept a
directory as its source, only a list of files.  I'm not sure of any other way to
get copy to work properly without erroring out if validation_files.txt hasn't
been created yet.  

I have been unable to get an entire directory copied in any way other than using
the python script.  The main problem I see with copying in the python script
instead of using the copy action is that ninja will not know to rerun the script
if a file is added or removed from the data/validation directory.  I thought
this would be solved by adding `data = [ "data/validation/" ]`, but it does not
seem to be doing the trick.  

Do you have any ideas on how to get copy to work properly, or to get the action
command to rerun on any changes in the validation/ directory, or maybe just a
different strategy altogether that may work better?

+  ]
+  args = rebase_path([ "data/validation" ] + outputs, root_build_dir)
+}
+
 mojom("test_interfaces") {
   testonly = true
   sources = [
     "math_calculator.mojom",
     "no_module.mojom",
     "ping_service.mojom",
     "rect.mojom",
     "regression_tests.mojom",
     "sample_factory.mojom",
     "sample_interfaces.mojom",
@@ skipping 174 matching lines @@
   ]
 }
 
 mojom("test_no_sources") {
   testonly = true
 
   public_deps = [
     ":test_interfaces",
   ]
 }