Add pytest tests to cmake

Tests can be executed similar to test binaries from build folder by
calling wrapper shellscript `run_pytest.sh`. This wrapper forwards all
arguments to pytest and exports the requried environment variables to
locations as found during the cmake configure process.

CMakeLists.txt

@@ -25,7 +25,7 @@ if (HAVE_GRIBJUMP_LOCAL_EXTRACT)
   set(GRIBJUMP_HAVE_FDB 1)
 
   ecbuild_find_package( NAME eccodes VERSION 2.32.1 REQUIRED )
-  
+
   ### AEC
   # Override eccodes' aec with our own: we need a newer version.
   unset(AEC_INCLUDE_DIRS CACHE)
@@ -46,14 +46,18 @@ if (HAVE_GRIBJUMP_LOCAL_EXTRACT)
 
 endif()
 
+ecbuild_add_option( FEATURE PYTHON_API_TESTS
+                    DEFAULT ON
+                    DESCRIPTION "Will execute python tests against pygribjump / libgribjump")
+
 ########################################################################################################################
 # contents
 
 include(cmake/compiler_warnings.cmake) # optionally handle compiler specific warnings
 
 set( gribjump_INCLUDE_DIRS  ${CMAKE_CURRENT_SOURCE_DIR}/src ${CMAKE_CURRENT_BINARY_DIR}/src )
 
-include_directories( 
+include_directories(
   ${AEC_INCLUDE_DIRS}
   ${gribjump_INCLUDE_DIRS}
   ${eckit_INCLUDE_DIRS}
@@ -70,6 +74,48 @@ if (HAVE_GRIBJUMP_LOCAL_EXTRACT)
   add_subdirectory( tests )
 endif()
 
+if(HAVE_PYTHON_API_TESTS)
+    ecbuild_find_package( NAME Python
+                          VERSION 3.10
+                          COMPONENTS Interpreter
+                          REQUIRED )
+
+    set(FDB5_DIR "${fdb5_DIR}/../../..")
+    configure_file(
+        ${CMAKE_SOURCE_DIR}/cmake/run_pytest.sh.in
+        ${CMAKE_BINARY_DIR}/run_pytest.sh
+        @ONLY
+    )
+
+    function(find_python_library python_lib)
+        execute_process(
+                COMMAND
+                ${Python_EXECUTABLE} "-c" "import ${python_lib}; print(${python_lib}.__version__)"
+                RESULT_VARIABLE status
+                OUTPUT_VARIABLE python_lib_version
+                ERROR_QUIET
+                OUTPUT_STRIP_TRAILING_WHITESPACE
+        )
+        if(NOT status)
+            message("Found Python module ${python_lib} ${python_lib_version}")
+        else()
+            message(FATAL_ERROR "Did not find package ${python_lib}")
+        endif()
+    endfunction()
+    find_python_library(cffi)
+    find_python_library(numpy)
+    find_python_library(pytest)
+    find_python_library(setuptools)
+    find_python_library(findlibs)
+
+    add_test(
+        NAME run_pytests
+        COMMAND ${CMAKE_BINARY_DIR}/run_pytest.sh -vv -s
+                --basetemp=${CMAKE_BINARY_DIR}/pytest-out
+    )
+
+endif()
+
 ########################################################################################################################
 # PLUGIN
 # Write and install the manifest file for the plugin

cmake/run_pytest.sh.in

@@ -0,0 +1,8 @@
+#! /usr/bin/env bash
+
+export GRIBJUMP_HOME="@CMAKE_BINARY_DIR@"
+export FDB5_DIR="@FDB5_DIR@"
+export PYTHONPATH="${PYTHONPATH}:@CMAKE_SOURCE_DIR@/pygribjump/src"
+
+@Python_EXECUTABLE@ -m pytest @CMAKE_SOURCE_DIR@ --basetemp="@CMAKE_BINARY_DIR@/test-results" "$@"
+