ctest: Improve errors when no preset is specified

Apply the same logic to both "equals" and non-"equals" forms of the
argument when no preset is specified, and add test cases.

Source/cmCTest.cxx

@@ -1835,7 +1835,12 @@ int cmCTest::Run(std::vector<std::string> const& args)
     } else {
       if (cmHasLiteralPrefix(*it, "--preset=")) {
         auto const& presetName = it->substr(9);
-        success = this->SetArgsFromPreset(presetName, listPresets);
+        if (presetName.empty()) {
+          cmSystemTools::Error("'--preset' requires an argument");
+          success = false;
+        } else {
+          success = this->SetArgsFromPreset(presetName, listPresets);
+        }
       } else if (++it != args.end()) {
         auto const& presetName = *it;
         success = this->SetArgsFromPreset(presetName, listPresets);

Tests/RunCMake/CMakePresetsTest/PresetsNoArg-test-result.txt

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

Tests/RunCMake/CMakePresetsTest/PresetsNoArg-test-stderr.txt

@@ -0,0 +1 @@
+^CMake Error: '--preset' requires an argument$

Tests/RunCMake/CMakePresetsTest/PresetsNoArgEq-test-result.txt

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

Tests/RunCMake/CMakePresetsTest/PresetsNoArgEq-test-stderr.txt

@@ -0,0 +1 @@
+^CMake Error: '--preset' requires an argument$

Tests/RunCMake/CMakePresetsTest/RunCMakeTest.cmake

@@ -95,6 +95,9 @@ set(CMakePresetsTest_NO_CONFIGURE 1)
 set(CMakePresetsTest_FILE "${RunCMake_SOURCE_DIR}/Good.json.in")
 run_cmake_test_presets(ListPresets "" "" "x" "--list-presets")
 
+run_cmake_command(PresetsNoArg-test ${CMAKE_CTEST_COMMAND} "--preset")
+run_cmake_command(PresetsNoArgEq-test ${CMAKE_CTEST_COMMAND} "--preset=")
+
 set(CMakePresetsTest_FILE "${RunCMake_SOURCE_DIR}/Condition.json.in")
 run_cmake_test_presets(ConditionListPresets "" "" "x" "--list-presets")
 unset(CMakePresetsTest_NO_CONFIGURE)