Tests: Generate simpler ExternalProject sample Git repositories

The `gitrepo.tgz` repository contains a project that enables both
C and CXX languages and builds source code.  This take a long time
to repeat over and over, particularly on Visual Studio and Xcode
generators.  Add and use a script to generate a new test repository
that has a much simpler project.

Issue: #20733

Tests/ExternalProject/CMakeLists.txt

@@ -329,7 +329,7 @@ if(do_git_tests)
   set(proj TutorialStep1-GIT-byhash)
   ExternalProject_Add(${proj}
     GIT_REPOSITORY "${local_git_repo}"
-    GIT_TAG d1970730310fe8bc07e73f15dc570071f9f9654a
+    GIT_TAG 57418671a0a0e371e7bac532337152595fbe0df5 # generated by gitrepo.bash
     UPDATE_COMMAND ""
     CMAKE_GENERATOR "${CMAKE_GENERATOR}"
     CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
@@ -664,23 +664,23 @@ endif()
 
 if(do_git_tests)
   add_test(TutorialStep1-GIT-byhash
-    "${binary_base}/TutorialStep1-GIT-byhash/Tutorial" 100)
+    ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-byhash/example.cmake")
 
   add_test(TutorialStep1-GIT-bytag
-    "${binary_base}/TutorialStep1-GIT-bytag/Tutorial" 99)
+    ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-bytag/example.cmake")
 
   add_test(TutorialStep1-GIT-bytag-withsubmodules
-    "${binary_base}/TutorialStep1-GIT-bytag-withsubmodules/Tutorial" 99)
+    ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-bytag-withsubmodules/example.cmake")
 
   add_test(TutorialStep1-GIT-shallow-master
-    "${binary_base}/TutorialStep1-GIT-shallow-master/Tutorial" 98)
+    ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-shallow-master/example.cmake")
 
   add_test(TutorialStep1-GIT-master
-    "${binary_base}/TutorialStep1-GIT-master/Tutorial" 98)
+    ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-master/example.cmake")
 
   if(NOT git_version VERSION_LESS 1.7.7)
     add_test(TutorialStep1-GIT-config
-      "${binary_base}/TutorialStep1-GIT-config/Tutorial" 98)
+      ${CMAKE_COMMAND} -P "${binary_base}/TutorialStep1-GIT-config/example.cmake")
   endif()
 endif()
 

Tests/ExternalProject/gitrepo.bash

@@ -0,0 +1,129 @@
+#!/usr/bin/env bash
+
+set -e
+set -x
+
+readonly tmpdir="$(mktemp -d)"
+trap "rm -rf '$tmpdir'" EXIT
+
+readonly outdir="${BASH_SOURCE%/*}"
+readonly defaultBranch='master'
+
+export GIT_AUTHOR_NAME='testauthor'
+export GIT_AUTHOR_EMAIL='[email protected]'
+export GIT_COMMITTER_NAME='testauthor'
+export GIT_COMMITTER_EMAIL='[email protected]'
+
+(
+cd "$tmpdir"
+
+git --bare init -b "$defaultBranch" gitrepo.git
+rm -f gitrepo.git/hooks/*.sample
+
+mkdir gitrepo
+cd gitrepo
+git init -b "$defaultBranch"
+echo 'cmake_minimum_required(VERSION 3.19)
+project(Example NONE)
+add_custom_target(example ALL
+  COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/example.cmake.in example.cmake
+)' >CMakeLists.txt
+echo 'message(STATUS example)' >example.cmake.in
+git add CMakeLists.txt example.cmake.in
+git commit -m "Initial import into repo."
+git push ../gitrepo.git "$defaultBranch"
+cd ../gitrepo.git
+git gc --prune
+cd ..
+ln -s gitrepo.git GIT
+
+git --bare init -b "$defaultBranch" gitrepo-sub.git
+rm -f gitrepo-sub.git/hooks/*.sample
+
+mkdir gitrepo-sub
+cd gitrepo-sub
+git init -b "$defaultBranch"
+echo 'cmake_minimum_required(VERSION 3.19)
+project(ExampleWithSub NONE)
+file(STRINGS "${CMAKE_SOURCE_DIR}/.git/config" git_config_strings
+     REGEX "^\\[submodule")
+foreach(submodule m1 m2)
+  option(WITH_${submodule} "Enable ${submodule}" OFF)
+  set(${submodule}_INITED FALSE)
+  set(${submodule}_UPDATED FALSE)
+  foreach(s ${git_config_strings})
+    if("${s}" MATCHES "${submodule}")
+      set(${submodule}_INITED TRUE)
+    endif()
+  endforeach()
+  if(EXISTS "${CMAKE_SOURCE_DIR}/m/${submodule}/CMakeLists.txt")
+    set(${submodule}_UPDATED TRUE)
+  endif()
+  if(WITH_${submodule})
+    if(NOT ${submodule}_INITED)
+      message(FATAL_ERROR "${submodule} not inited")
+    elseif(NOT ${submodule}_UPDATED)
+      message(FATAL_ERROR "${submodule} not updated")
+    endif()
+  else()
+    if(${submodule}_INITED)
+      message(FATAL_ERROR "${submodule} inited")
+    elseif(${submodule}_UPDATED)
+      message(FATAL_ERROR "${submodule} updated")
+    endif()
+  endif()
+endforeach()' >CMakeLists.txt
+git add CMakeLists.txt
+git submodule add -- ../GIT m/m1
+git submodule add -- ../GIT m/m2
+git submodule add -- ../GIT m/m3
+git commit -m "Initial import into repo."
+git push ../gitrepo-sub.git "$defaultBranch"
+cd ../gitrepo-sub.git
+git gc --prune
+cd ..
+ln -s gitrepo-sub.git GIT-with-submodules
+
+git --bare init -b "$defaultBranch" gitrepo-sub-rec.git
+rm -f gitrepo-sub-rec.git/hooks/*.sample
+
+mkdir gitrepo-sub-rec
+cd gitrepo-sub-rec
+git init -b "$defaultBranch"
+echo 'cmake_minimum_required(VERSION 3.19)
+project(ExampleWithRecSub NONE)
+set(top_submodule_dir "${CMAKE_SOURCE_DIR}/submodule")
+if(NOT EXISTS "${top_submodule_dir}/CMakeLists.txt")
+  message(FATAL_ERROR "Top submodule not updated")
+endif()
+option(WITH_RECURSIVE "Submodules are updated recursively" ON)
+foreach(submodule m1 m2 m3)
+  set(${submodule}_UPDATED FALSE)
+  if(EXISTS "${top_submodule_dir}/m/${submodule}/CMakeLists.txt")
+    set(${submodule}_UPDATED TRUE)
+  endif()
+  if(WITH_RECURSIVE)
+    if(NOT ${submodule}_UPDATED)
+      message(FATAL_ERROR "${submodule} not updated")
+    endif()
+  else()
+    if(${submodule}_UPDATED)
+      message(FATAL_ERROR "${submodule} updated")
+    endif()
+  endif()
+endforeach()' >CMakeLists.txt
+git add CMakeLists.txt
+git submodule add -- ../GIT-with-submodules submodule
+git commit -m "Initial import into repo."
+git push ../gitrepo-sub-rec.git "$defaultBranch"
+cd ../gitrepo-sub-rec.git
+git gc --prune
+cd ..
+)
+
+tar cvzf "$outdir/gitrepo.tgz" -C "$tmpdir" gitrepo.git
+tar cvzf "$outdir/gitrepo-sub.tgz" -C "$tmpdir" gitrepo-sub.git
+tar cvzf "$outdir/gitrepo-sub-rec.tgz" -C "$tmpdir" gitrepo-sub-rec.git
+
+git_tag=$(cd "$tmpdir/gitrepo.git" ; git rev-parse HEAD)
+sed -i "/generated by gitrepo.bash/ s/ [0-9a-f]\\+ / $git_tag /" "$outdir/CMakeLists.txt"