Add new reporter event called for each test case enter/exit

This means that e.g. for `TEST_CASE` with two sibling `SECTION`s
the event will fire twice, because the `TEST_CASE` will be entered
twice.

Closes #2107 (the event mentioned there already exists, but this
is its counterpart that we also want to provide to users)

tests/ExtraTests/CMakeLists.txt

@@ -172,6 +172,14 @@ if (MSVC)
     list(APPEND CATCH_WARNING_TARGETS ${EXTRA_TEST_BINARIES} WindowsHeader)
 endif()
 
+
+add_executable(PartialTestCaseEvents ${TESTS_DIR}/X21-PartialTestCaseEvents.cpp)
+target_link_libraries(PartialTestCaseEvents PRIVATE Catch2WithMain)
+add_test(
+  NAME PartialTestCaseEvents
+  COMMAND ${PYTHON_EXECUTABLE} ${CATCH_DIR}/tests/TestScripts/testPartialTestCaseEvent.py $<TARGET_FILE:PartialTestCaseEvents>
+)
+
 #add_executable(DebugBreakMacros ${TESTS_DIR}/X12-CustomDebugBreakMacro.cpp)
 #target_link_libraries(DebugBreakMacros Catch2)
 #add_test(NAME DebugBreakMacros COMMAND DebugBreakMacros --break)

tests/ExtraTests/X21-PartialTestCaseEvents.cpp

@@ -0,0 +1,74 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+/**\file
+ * Registers custom reporter that reports testCase* events
+ *
+ * The resulting executable can then be used by an external Python script
+ * to verify that testCase{Starting,Ended} and testCasePartial{Starting,Ended}
+ * events are properly nested.
+ */
+
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/reporters/catch_reporter_streaming_base.hpp>
+#include <catch2/catch_test_case_info.hpp>
+#include <catch2/catch_reporter_registrars.hpp>
+#include <catch2/generators/catch_generators.hpp>
+
+
+#include <iostream>
+
+using Catch::TestCaseInfo;
+using Catch::TestCaseStats;
+
+class PartialReporter : public Catch::StreamingReporterBase {
+public:
+    using StreamingReporterBase::StreamingReporterBase;
+
+    ~PartialReporter() override; // = default
+
+    static std::string getDescription() {
+        return "Special reporter for testing TestCasePartialStarting/Ended events";
+    }
+
+    //! Called _once_ for each TEST_CASE, no matter how many times it is entered
+    void testCaseStarting(TestCaseInfo const& testInfo) override {
+        std::cout << "TestCaseStarting: " << testInfo.name << '\n';
+    }
+    //! Called _every time_ a TEST_CASE is entered, including repeats (due to sections)
+    void testCasePartialStarting(TestCaseInfo const& testInfo, uint64_t partNumber) override {
+        std::cout << "TestCaseStartingPartial: " << testInfo.name << '#' << partNumber << '\n';
+    }
+
+
+    //! Called _every time_ a TEST_CASE is entered, including repeats (due to sections)
+    void testCasePartialEnded(TestCaseStats const& testCaseStats, uint64_t partNumber) override {
+        std::cout << "TestCasePartialEnded: " << testCaseStats.testInfo->name << '#' << partNumber << '\n';
+    }
+    //! Called _once_ for each TEST_CASE, no matter how many times it is entered
+    void testCaseEnded(TestCaseStats const& testCaseStats) override {
+        std::cout << "TestCaseEnded: " << testCaseStats.testInfo->name << '\n';
+    }
+};
+PartialReporter::~PartialReporter() = default;
+
+
+CATCH_REGISTER_REPORTER("partial", PartialReporter)
+
+TEST_CASE("section") {
+    SECTION("A") {}
+    SECTION("B") {}
+    SECTION("C") {}
+    SECTION("D") {}
+}
+
+TEST_CASE("generator") {
+    auto _ = GENERATE(1, 2, 3, 4);
+    (void)_;
+}