ENH: Split testing data tarball form source tarball.

This is based off VTK:

  https://gitlab.kitware.com/vtk/vtk/commit/bf5cf3cf8f

but a single data tarball is generated.  The source and data tarballs are
split, and the data can be extracted in the source tree.  BUILD_TESTING is OFF
by default in the source tarball when the testing data is not present.

Suggested-by: Brad King <brad.king@kitware.com>

ITK-3355

Change-Id: I96fb33d20ca832d6ec14b52e44625185a4e68bd8

.ExternalData/README.rst

@@ -0,0 +1,6 @@
+.ExternalData
+=============
+
+The ITK ``.ExternalData`` directory is an object store for the
+CMake ExternalData module that ITK uses to manage test input
+and baseline data.

CMakeLists.txt

@@ -212,9 +212,18 @@ set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}
 set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}")
 set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${ITK_REQUIRED_LINK_FLAGS}")
 
+#-----------------------------------------------------------------------------
+if(NOT EXISTS "${ITK_SOURCE_DIR}/.ExternalData/README.rst")
+  # This file is always present in version-controlled source trees
+  # so we must have been extracted from a source tarball with no
+  # data objects needed for testing.  Turn off tests by default
+  # since enabling them requires network access or manual data
+  # store configuration.
+  option(BUILD_TESTING "Build the testing tree." OFF)
+endif()
 include(CTest)
 
-include( CppcheckTargets )
+include(CppcheckTargets)
 
 # Setup build locations.
 if(NOT CMAKE_RUNTIME_OUTPUT_DIRECTORY)

Utilities/Maintenance/SourceTarball.bash

@@ -89,30 +89,39 @@ index_data_objects() {
 }
 
 load_data_objects() {
-  find_data_objects "$1" |
+  find_data_objects "$@" |
   index_data_objects
   return_pipe_status
 }
 
+load_data_files() {
+  git ls-tree -r "$1" -- '.ExternalData' |
+  git update-index --index-info
+  return_pipe_status
+}
+
 git_archive_tgz() {
   out="$2.tar.gz" && tmp="$out.tmp$$" &&
-  git -c core.autocrlf=false archive $verbose --format=tar --prefix=$2/ $1 |
+  if test -n "$3"; then prefix="$3"; else prefix="$2"; fi &&
+  git -c core.autocrlf=false archive $verbose --format=tar --prefix=$prefix/ $1 |
   gzip -9 > "$tmp" &&
   mv "$tmp" "$out" &&
   info "Wrote $out"
 }
 
 git_archive_txz() {
   out="$2.tar.xz" && tmp="$out.tmp$$" &&
-  git -c core.autocrlf=false archive $verbose --format=tar --prefix=$2/ $1 |
+  if test -n "$3"; then prefix="$3"; else prefix="$2"; fi &&
+  git -c core.autocrlf=false archive $verbose --format=tar --prefix=$prefix/ $1 |
   xz -9 > "$tmp" &&
   mv "$tmp" "$out" &&
   info "Wrote $out"
 }
 
 git_archive_zip() {
   out="$2.zip" && tmp="$out.tmp$$" &&
-  git -c core.autocrlf=true archive $verbose --format=zip --prefix=$2/ $1 > "$tmp" &&
+  if test -n "$3"; then prefix="$3"; else prefix="$2"; fi &&
+  git -c core.autocrlf=true archive $verbose --format=zip --prefix=$prefix/ $1 > "$tmp" &&
   mv "$tmp" "$out" &&
   info "Wrote $out"
 }
@@ -156,18 +165,30 @@ fi
 
 # Create temporary git index to construct source tree
 export GIT_INDEX_FILE="$(pwd)/tmp-$$-index" &&
-trap "rm -rf '$GIT_INDEX_FILE'" EXIT &&
+trap "rm -f '$GIT_INDEX_FILE'" EXIT &&
 
-info "Loading tree from $commit..." &&
+result=0 &&
+
+info "Loading source tree from $commit..." &&
+rm -f "$GIT_INDEX_FILE" &&
 git read-tree -m -i $commit &&
+git rm -rf -q --cached '.ExternalData' &&
+tree=$(git write-tree) &&
+
+info "Generating source archive(s)..." &&
+for fmt in $formats; do
+  git_archive_$fmt $tree "InsightToolkit-$version" || result=1
+done &&
 
 info "Loading data for $commit..." &&
+rm -f "$GIT_INDEX_FILE" &&
 load_data_objects $commit &&
-
-info "Generating source archive..." &&
+load_data_files $commit &&
 tree=$(git write-tree) &&
-result=0 &&
+
+info "Generating data archive(s)..." &&
 for fmt in $formats; do
-  git_archive_$fmt $tree "InsightToolkit-$version" || result=1
+  git_archive_$fmt $tree "InsightData-$version" "InsightToolkit-$version" || result=1
 done &&
+
 exit $result