ExternalData: Test content link with a space in its name

Extend the Module.ExternalData test to cover a DATA{} reference whose
name contains a space.  Skip the case when the native build tool does
not support spaces.

Tests/CMakeLists.txt

@@ -347,6 +347,7 @@ if(BUILD_TESTING)
     --build-project ExternalDataTest
     --build-noclean
     --force-new-ctest-process
+    --build-options -DMAKE_SUPPORTS_SPACES=${MAKE_SUPPORTS_SPACES}
     --test-command ${CMAKE_CTEST_COMMAND} -C \${CTEST_CONFIGURATION_TYPE} -V
     )
   list(APPEND TEST_BUILD_DIRS "${CMake_BINARY_DIR}/Tests/Module/ExternalData")

Tests/Module/ExternalData/CMakeLists.txt

@@ -14,10 +14,15 @@ set(ExternalData_URL_TEMPLATES
 set(ExternalData_BINARY_ROOT "${CMAKE_CURRENT_BINARY_DIR}/ExternalData")
 file(REMOVE_RECURSE ${ExternalData_BINARY_ROOT}) # clean test
 
+if(MAKE_SUPPORTS_SPACES)
+  set(Data1CheckSpaces -D "DataSpace=DATA{Data Space.dat}")
+endif()
+
 ExternalData_Add_Test(Data1
   NAME Data1Check
   COMMAND ${CMAKE_COMMAND}
     -D Data=DATA{Data.dat}
+    ${Data1CheckSpaces}
     -D SeriesA=DATA{SeriesA.dat,:}
     -D SeriesB=DATA{SeriesB.dat,:}
     -D SeriesC=DATA{SeriesC.dat,:}

Tests/Module/ExternalData/Data Space.dat.md5

@@ -0,0 +1 @@
+8c018830e3efa5caf3c7415028335a57

Tests/Module/ExternalData/Data1Check.cmake

@@ -2,6 +2,12 @@ file(STRINGS "${Data}" lines LIMIT_INPUT 1024)
 if(NOT "x${lines}" STREQUAL "xInput file already transformed.")
   message(SEND_ERROR "Input file:\n  ${Data}\ndoes not have expected content, but [[${lines}]]")
 endif()
+if(DEFINED DataSpace)
+  file(STRINGS "${DataSpace}" lines LIMIT_INPUT 1024)
+  if(NOT "x${lines}" STREQUAL "xInput file already transformed.")
+    message(SEND_ERROR "Input file:\n  ${DataSpace}\ndoes not have expected content, but [[${lines}]]")
+  endif()
+endif()
 set(SeriesAn1 "1\\.dat")
 set(SeriesBn1 "_1\\.dat")
 set(SeriesCn1 "\\.1\\.dat")