add test for interop with abseil

recipe/cmake_test/CMakeLists.txt

@@ -0,0 +1,6 @@
+project(cf_dummy LANGUAGES CXX)
+cmake_minimum_required(VERSION 3.12)
+find_package(absl REQUIRED CONFIG)
+
+add_executable(re2_example re2_example.cpp)
+target_link_libraries(re2_example absl::flags absl::strings)

recipe/cmake_test/re2_example.cpp

@@ -0,0 +1,16 @@
+// try that conversion from absl::string_view to re2::StringPiece works
+
+#include "absl/strings/string_view.h"
+#include "re2/stringpiece.h"
+
+absl::string_view some_function(absl::string_view text) {
+  return text;
+}
+
+int main() {
+   re2::StringPiece sp = "hello, world";
+   // should be transformable between types by compiler
+   some_function(sp)
+
+   return 0;
+}

recipe/meta.yaml

@@ -30,6 +30,13 @@ requirements:
   run:
 
 test:
+  requires:
+    - {{ compiler('cxx') }}
+    - cmake
+    - libabseil
+    - ninja
+  files:
+    - cmake_test/
   commands:
     - test -f ${PREFIX}/lib/libre2.so  # [linux]
     - test -f ${PREFIX}/lib/libre2.dylib  # [osx]
@@ -41,6 +48,14 @@ test:
     - if exist %PREFIX%\\Library\\lib\\re2_static.lib exit 1  # [win]
     - if not exist %PREFIX%\\Library\\bin\\re2.dll exit 1  # [win]
 
+    # CMake integration
+    - cd cmake_test
+    - cmake $CMAKE_ARGS  -GNinja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=17 .  # [unix]
+    - cmake %CMAKE_ARGS% -GNinja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=17 .  # [win]
+    - cmake --build .
+    - ./re2_example    # [unix]
+    - re2_example.exe  # [win]
+
 about:
   home: https://github.com/google/re2/
   license: BSD-3-Clause