ctest: Add support for '--prefix=<prefix>' form of the argument

The main `cmake --preset` argument for configure presets supports both
forms, so support it for `ctest --preset` too.

Fixes: #21855

Help/manual/ctest.1.rst

@@ -30,7 +30,7 @@ This program will run the tests and report results.
 Options
 =======
 
-``--preset <preset>``
+``--preset <preset>``, ``--preset=<preset>``
  Use a test preset to specify test options. The project binary directory
  is inferred from the ``configurePreset`` key. The current working directory
  must contain CMake preset files.

Source/cmCTest.cxx

@@ -2574,7 +2574,10 @@ int cmCTest::Run(std::vector<std::string>& args, std::string* output)
 
   bool listPresets =
     find(args.begin(), args.end(), "--list-presets") != args.end();
-  auto it = find(args.begin(), args.end(), "--preset");
+  auto it =
+    std::find_if(args.begin(), args.end(), [](std::string const& arg) -> bool {
+      return arg == "--preset" || cmHasLiteralPrefix(arg, "--preset=");
+    });
   if (listPresets || it != args.end()) {
     std::string errormsg;
     bool success;
@@ -2583,7 +2586,10 @@ int cmCTest::Run(std::vector<std::string>& args, std::string* output)
       // If listing presets we don't need a presetName
       success = this->SetArgsFromPreset("", listPresets);
     } else {
-      if (++it != args.end()) {
+      if (cmHasLiteralPrefix(*it, "--preset=")) {
+        auto presetName = it->substr(9);
+        success = this->SetArgsFromPreset(presetName, listPresets);
+      } else if (++it != args.end()) {
         auto presetName = *it;
         success = this->SetArgsFromPreset(presetName, listPresets);
       } else {

Source/ctest.cxx

@@ -26,7 +26,8 @@ static const char* cmDocumentationUsage[][2] = { { nullptr,
                                                  { nullptr, nullptr } };
 
 static const char* cmDocumentationOptions[][2] = {
-  { "--preset <preset>", "Read arguments from a test preset." },
+  { "--preset <preset>, --preset=<preset>",
+    "Read arguments from a test preset." },
   { "--list-presets", "List available test presets." },
   { "-C <cfg>, --build-config <cfg>", "Choose configuration to test." },
   { "--progress", "Enable short progress output from tests." },

Tests/RunCMake/CMakePresetsTest/RunCMakeTest.cmake

@@ -51,6 +51,7 @@ function(run_cmake_test_presets name CMakePresetsTest_CONFIGURE_PRESETS CMakePre
     endforeach()
   endif()
 
+  set(eq 0)
   foreach(TEST_PRESET ${CMakePresetsTest_TEST_PRESETS})
     if (EXISTS "${RunCMake_SOURCE_DIR}/${name}-test-${TEST_PRESET}-check.cmake")
       set(RunCMake-check-file "${name}-test-${TEST_PRESET}-check.cmake")
@@ -58,8 +59,15 @@ function(run_cmake_test_presets name CMakePresetsTest_CONFIGURE_PRESETS CMakePre
       set(RunCMake-check-file "check.cmake")
     endif()
 
-    run_cmake_command(${name}-test-${TEST_PRESET}
-      ${CMAKE_CTEST_COMMAND} "--preset" "${TEST_PRESET}" ${ARGN})
+    if(eq)
+      run_cmake_command(${name}-test-${TEST_PRESET}
+        ${CMAKE_CTEST_COMMAND} "--preset=${TEST_PRESET}" ${ARGN})
+      set(eq 0)
+    else()
+      run_cmake_command(${name}-test-${TEST_PRESET}
+        ${CMAKE_CTEST_COMMAND} "--preset" "${TEST_PRESET}" ${ARGN})
+      set(eq 1)
+    endif()
   endforeach()
 endfunction()