Tests: Test setting a generator platform in a toolchain file

Teach the RunCMake.GeneratorPlatform test to cover setting
CMAKE_GENERATOR_PLATFORM in a file loaded by CMAKE_TOOLCHAIN_FILE.

Tests/RunCMake/GeneratorPlatform/BadPlatform-toolchain.cmake

@@ -0,0 +1 @@
+set(CMAKE_GENERATOR_PLATFORM "Bad Platform")

Tests/RunCMake/GeneratorPlatform/BadPlatformToolchain-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/GeneratorPlatform/BadPlatformToolchain-stderr.txt

@@ -0,0 +1,10 @@
+CMake Error at CMakeLists.txt:[0-9]+ \(project\):
+  Generator
+
+    .*
+
+  does not support platform specification, but platform
+
+    Bad Platform
+
+  was specified.$

Tests/RunCMake/GeneratorPlatform/BadPlatformToolchain.cmake

@@ -0,0 +1 @@
+message(FATAL_ERROR "This should not be reached!")

Tests/RunCMake/GeneratorPlatform/RunCMakeTest.cmake

@@ -16,3 +16,13 @@ set(RunCMake_GENERATOR_TOOLSET "")
 set(RunCMake_TEST_OPTIONS -A "Extra Platform")
 run_cmake(TwoPlatforms)
 unset(RunCMake_TEST_OPTIONS)
+
+if("${RunCMake_GENERATOR}" MATCHES "^Visual Studio ([89]|1[0124])( 20[0-9][0-9])?$")
+  set(RunCMake_TEST_OPTIONS -DCMAKE_TOOLCHAIN_FILE=${RunCMake_SOURCE_DIR}/TestPlatform-toolchain.cmake)
+  run_cmake(TestPlatformToolchain)
+  unset(RunCMake_TEST_OPTIONS)
+else()
+  set(RunCMake_TEST_OPTIONS -DCMAKE_TOOLCHAIN_FILE=${RunCMake_SOURCE_DIR}/BadPlatform-toolchain.cmake)
+  run_cmake(BadPlatformToolchain)
+  unset(RunCMake_TEST_OPTIONS)
+endif()

Tests/RunCMake/GeneratorPlatform/TestPlatform-toolchain.cmake

@@ -0,0 +1 @@
+set(CMAKE_GENERATOR_PLATFORM "Test Platform")

Tests/RunCMake/GeneratorPlatform/TestPlatformToolchain-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/GeneratorPlatform/TestPlatformToolchain-stderr.txt

@@ -0,0 +1,9 @@
+CMake Error at TestPlatformToolchain.cmake:[0-9]+ \(message\):
+  CMAKE_GENERATOR_PLATFORM is "Test Platform" as expected.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
++
+CMake Error at TestPlatformToolchain.cmake:[0-9]+ \(message\):
+  CMAKE_VS_PLATFORM_NAME is "Test Platform" as expected.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/GeneratorPlatform/TestPlatformToolchain.cmake

@@ -0,0 +1,16 @@
+if("x${CMAKE_GENERATOR_PLATFORM}" STREQUAL "xTest Platform")
+  message(SEND_ERROR "CMAKE_GENERATOR_PLATFORM is \"Test Platform\" as expected.")
+else()
+  message(FATAL_ERROR
+    "CMAKE_GENERATOR_PLATFORM is \"${CMAKE_GENERATOR_PLATFORM}\" "
+    "but should be \"Test Platform\"!")
+endif()
+if(CMAKE_GENERATOR MATCHES "Visual Studio")
+  if("x${CMAKE_VS_PLATFORM_NAME}" STREQUAL "xTest Platform")
+    message(SEND_ERROR "CMAKE_VS_PLATFORM_NAME is \"Test Platform\" as expected.")
+  else()
+    message(FATAL_ERROR
+      "CMAKE_VS_PLATFORM_NAME is \"${CMAKE_VS_PLATFORM_NAME}\" "
+      "but should be \"Test Platform\"!")
+  endif()
+endif()