Fill in testing Dockerfile stub.

blimp/engine/testing/Dockerfile

Index: blimp/engine/testing/Dockerfile
diff --git a/blimp/engine/testing/Dockerfile b/blimp/engine/testing/Dockerfile
index 711535347dce4aa52f8bb5e3a6fc7314a5f3f357..83aca2f31a91a9377237079ec84936ecb34d6fa0 100644
--- a/blimp/engine/testing/Dockerfile
+++ b/blimp/engine/testing/Dockerfile
@@ -1,2 +1,18 @@
-# Testing dockerfile stub
-# TODO(jessicag): Fill in (crbug.com/616945).
+# This Dockerfile is used to build a filesystem enviornment containing

[Wez, 2016/07/12 20:34:03]

typo: environment

[Jess, 2016/07/12 21:40:25]

Done.

+# binaries and required files for Blimp Engine test and tests for dependencies
+# of Blimp Engine. It is built on a base image (base:latest) that is also used

[Wez, 2016/07/12 20:34:03]

nit: wording; suggest "... on the same base image that is used to run the Engine
itself."

[Jess, 2016/07/12 21:40:25]

Done.

+# for running the Engine itself.
+FROM base:latest
+
+RUN mkdir -p /out/test/
+
+# The glob below expands to all files, but does not add directories
+# recursively.
+# Test binaries assume src directory is 2 levels down. While this behavior can
+# be changed with flags, the directory stucture is set up to minimize

[Wez, 2016/07/12 20:34:03]

typo: structure

[Jess, 2016/07/12 21:40:25]

Done.

+# potential problems with initial integration.

[Wez, 2016/07/12 20:34:03]

I think what you're saying here is "add all the files, without recursing into
directories, and do so under a /two/part path to be consistent with test
binaries' expectation of the build output path?

My understanding was that with isolates, and now with GN, all test dependencies
end up under the output directory - "knowing" that the directory two levels up
was the source directory doesn't help unless we're also adding files from the
source tree to the bundle, surely?

[Jess, 2016/07/12 21:40:25]

There are data dependencies under the source tree that are added to the bundle,
specifically ../../base/test/data/.

[Wez, 2016/07/13 00:43:41]

Oh, interesting - so I suppose it would help in this comment to be clear as to
where those get added to the bundle, since it's not obvious at-a-glance. e.g.
are they part of base:latest?

[maniscalco, 2016/07/13 15:03:23]

Jess, correct me if I'm wrong, I believe they're getting pulled in to the
tarball that's fed to "docker build" because the dependencies are are properly
expressed via GN.

[Jess, 2016/07/13 17:06:46]

Nick's got it.

[Wez, 2016/07/13 18:32:05]

OK, so the issue is that when we build the tarball for the bundle, we include
test-data files _with their full source-directory-relative paths_, then?

[Jess, 2016/07/13 19:51:13]

Yes.

+ADD * /out/test/
+
+RUN chown -R blimp_user /out/test/
+
+USER blimp_user