Tests: Add RunCMake.BuildDepends test

This will allow more granular checks than the main BuildDepends test.
Start with a simple single-source C program.

Tests/RunCMake/BuildDepends/C-Exe.cmake

@@ -0,0 +1,12 @@
+enable_language(C)
+
+add_executable(main ${CMAKE_CURRENT_BINARY_DIR}/main.c)
+
+file(GENERATE OUTPUT check-$<LOWER_CASE:$<CONFIG>>.cmake CONTENT "
+set(check_pairs
+  \"$<TARGET_FILE:main>|${CMAKE_CURRENT_BINARY_DIR}/main.c\"
+  )
+set(check_exes
+  \"$<TARGET_FILE:main>\"
+  )
+")

Tests/RunCMake/BuildDepends/C-Exe.step1.cmake

@@ -0,0 +1,3 @@
+file(WRITE "${RunCMake_TEST_BINARY_DIR}/main.c" [[
+int main(void) { return 1; }
+]])

Tests/RunCMake/BuildDepends/C-Exe.step2.cmake

@@ -0,0 +1,3 @@
+file(WRITE "${RunCMake_TEST_BINARY_DIR}/main.c" [[
+int main(void) { return 2; }
+]])

Tests/RunCMake/BuildDepends/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.3)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/BuildDepends/RunCMakeTest.cmake

@@ -0,0 +1,23 @@
+include(RunCMake)
+
+function(run_BuildDepends CASE)
+  # Use a single build tree for a few tests without cleaning.
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${CASE}-build)
+  set(RunCMake_TEST_NO_CLEAN 1)
+  if(RunCMake_GENERATOR MATCHES "Make|Ninja")
+    set(RunCMake_TEST_OPTIONS -DCMAKE_BUILD_TYPE=Debug)
+  endif()
+  file(REMOVE_RECURSE "${RunCMake_TEST_BINARY_DIR}")
+  file(MAKE_DIRECTORY "${RunCMake_TEST_BINARY_DIR}")
+  include(${RunCMake_SOURCE_DIR}/${CASE}.step1.cmake OPTIONAL)
+  run_cmake(${CASE})
+  set(RunCMake-check-file check.cmake)
+  set(check_step 1)
+  run_cmake_command(${CASE}-build1 ${CMAKE_COMMAND} --build . --config Debug)
+  execute_process(COMMAND ${CMAKE_COMMAND} -E sleep 1.125) # handle 1s resolution
+  include(${RunCMake_SOURCE_DIR}/${CASE}.step2.cmake OPTIONAL)
+  set(check_step 2)
+  run_cmake_command(${CASE}-build2 ${CMAKE_COMMAND} --build . --config Debug)
+endfunction()
+
+run_BuildDepends(C-Exe)

Tests/RunCMake/BuildDepends/check.cmake

@@ -0,0 +1,34 @@
+if(EXISTS ${RunCMake_TEST_BINARY_DIR}/check-debug.cmake)
+  include(${RunCMake_TEST_BINARY_DIR}/check-debug.cmake)
+  foreach(exe IN LISTS check_exes)
+    execute_process(COMMAND ${exe} RESULT_VARIABLE res)
+    if(NOT res EQUAL ${check_step})
+      set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+ '${exe}' returned '${res}' but expected '${check_step}'
+")
+    endif()
+  endforeach()
+  foreach(p IN LISTS check_pairs)
+    if("${p}" MATCHES "^(.*)\\|(.*)$")
+      set(lhs "${CMAKE_MATCH_1}")
+      set(rhs "${CMAKE_MATCH_2}")
+      if(NOT EXISTS "${lhs}")
+        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+ '${lhs}' missing
+")
+      elseif(NOT EXISTS "${rhs}")
+        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+ '${rhs}' missing
+")
+      elseif(NOT "${lhs}" IS_NEWER_THAN "${rhs}")
+        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+ '${lhs}' is not newer than '${rhs}'
+")
+      endif()
+    endif()
+  endforeach()
+else()
+  set(RunCMake_TEST_FAILED "
+ '${RunCMake_TEST_BINARY_DIR}/check-debug.cmake' missing
+")
+endif()

Tests/RunCMake/CMakeLists.txt

@@ -124,6 +124,7 @@ if(NOT CMake_TEST_EXTERNAL_CMAKE)
     )
 endif()
 
+add_RunCMake_test(BuildDepends)
 if(UNIX AND "${CMAKE_GENERATOR}" MATCHES "Unix Makefiles|Ninja")
   add_RunCMake_test(CompilerChange)
 endif()